Interobserver variation among histopathologic evaluations of intestinal tissues from dogs and cats

Application of automated machine learning for histological evaluation of feline endoscopic samples

Differentiating intestinal T-cell lymphoma from chronic enteropathy (CE) in endoscopic samples is often challenging. In the present study, automated machine learning systems were developed to distinguish between the two diseases, predict clonality, and detect prognostic factors of intestinal lymphoma in cats. Four models were created for four experimental conditions: experiment 1 to distinguish between intestinal T-cell lymphoma and CE; experiment 2 to distinguish large cell lymphoma, small cell lymphoma, and CE; experiment 3 to distinguish granzyme B+ lymphoma, granzyme B- lymphoma, and CE; and experiment 4 to distinguish between T-cell receptor (TCR) clonal population and TCR polyclonal population. After each experiment, a pathologist reviewed the test images and scored for lymphocytic infiltration, epitheliotropism, and epithelial injury. The models of experiments 1-4 achieved area under the receiver operating characteristic curve scores of 0.943 (precision, 87.59%; recall, 87.59%), 0.962 (precision, 86.30%; recall, 86.30%), 0.904 (precision, 82.86%; recall, 80%), and 0.904 (precision, 81.25%; recall, 81.25%), respectively. The images predicted as intestinal T-cell lymphoma showed significant infiltration of lymphocytes and epitheliotropism than CE. These models can provide evaluation tools to assist pathologists with differentiating between intestinal T-cell lymphoma and CE.

Association of serum and fecal microRNA profiles in cats with gastrointestinal cancer and chronic inflammatory enteropathy

BACKGROUND

Differentiation of gastrointestinal cancer (GIC) from chronic inflammatory enteropathies (CIE) in cats can be challenging and often requires extensive diagnostic testing. MicroRNAs (miRNAs) have promise as non-invasive biomarkers in serum and feces for diagnosis of GIC.

HYPOTHESIS/OBJECTIVES

Cats with GIC will have serum and fecal miRNA profiles that differ significantly from healthy cats and cats with CIE. Identify serum and fecal miRNAs with diagnostic potential for differentiation between cats with GIC and CIE as compared to healthy cats.

ANIMALS

Ten healthy cats, 9 cats with CIE, and 10 cats with GIC; all client-owned.

METHODS

Cats were recruited for an international multicenter observational prospective case-control study. Serum and feces were screened using small RNA sequencing for miRNAs that differed in abundance between cats with GIC and CIE, and healthy cats. Diagnostic biomarker potential of relevant miRNAs from small RNA sequencing and the literature was confirmed using reverse transcription quantitative real-time PCR (RT-qPCR).

RESULTS

Serum miR-223-3p was found to distinguish between cats with GIC and CIE with an area under the curve (AUC) of 0.9 (95% confidence interval [CI], 0.760-1.0), sensitivity of 90% (95% CI, 59.6-99.5%), and specificity of 77.8% (95% CI, 45.3-96.1%). Serum miR-223-3p likewise showed promise in differentiating a subgroup of cats with small cell lymphoma (SCL) from those with CIE. No fecal miRNAs could distinguish between cats with GIC and CIE.

CONCLUSION AND CLINICAL IMPORTANCE

Serum miR-223-3p potentially may serve as a noninvasive diagnostic biomarker of GIC in cats, in addition to providing a much needed tool for the differentiation of CIE and SCL.

Histopathologic diagnosis and patient characteristics in cats with small intestinal obstructions secondary to trichobezoars

OBJECTIVES

The aim of the present study was to describe the distribution of gastrointestinal histopathology findings associated with gastrointestinal obstructions secondary to trichobezoar formation in cats.

METHODS

A total of 100 surgical gastrointestinal biopsies were obtained from 44 cats with gastrointestinal obstructions secondary to a trichobezoar. Medical records, including signalment, type and duration of clinical signs, surgical reports and histopathologic analysis, were reviewed for each cat.

RESULTS

Biopsies taken near the site of the trichobezoar were more likely to show neutrophilic inflammation and mucosal erosion/ulceration compared with biopsies taken elsewhere in the small intestine. Lymphoplasmacytic and mixed lymphocytic and eosinophilic populations were the most common histopathologic findings from all biopsies followed by alimentary small cell lymphoma. Biopsy samples were more likely to represent a diagnosis of alimentary lymphoma in cats older than 10 years.

CONCLUSIONS AND RELEVANCE

Gastrointestinal biopsies taken at the time of surgery in cats with trichobezoar obstructions may represent an important diagnostic tool for further evaluation of potential feline chronic enteropathy. Biopsies taken at the site of the obstruction should be interpreted cautiously as the presence of a trichobezoar may induce an acute inflammatory reaction. The resultant histologic interpretation at this site may not represent the chronic state of the intestinal mucosa, supporting the utility of obtaining multiple biopsies orad and aborad to the obstruction.

ACVIM consensus statement guidelines on diagnosing and distinguishing low-grade neoplastic from inflammatory lymphocytic chronic enteropathies in cats

BACKGROUND

Lymphoplasmacytic enteritis (LPE) and low-grade intestinal T cell lymphoma (LGITL) are common diseases in older cats, but their diagnosis and differentiation remain challenging.

OBJECTIVES

To summarize the current literature on etiopathogenesis and diagnosis of LPE and LGITL in cats and provide guidance on the differentiation between LPE and LGITL in cats. To provide statements established using evidence-based approaches or where such evidence is lacking, statements based on consensus of experts in the field.

ANIMALS

None.

METHODS

A panel of 6 experts in the field (2 internists, 1 radiologist, 1 anatomic pathologist, 1 clonality expert, 1 oncologist) with the support of a human medical immunologist, was formed to assess and summarize evidence in the peer-reviewed literature and complement it with consensus recommendations.

RESULTS

Despite increasing interest on the topic for clinicians and pathologists, few prospective studies were available, and interpretation of the pertinent literature often was challenging because of the heterogeneity of the cases. Most recommendations by the panel were supported by a moderate or low level of evidence. Several understudied areas were identified, including cellular markers using immunohistochemistry, genomics, and transcriptomic studies.

CONCLUSIONS AND CLINICAL IMPORTANCE

To date, no single diagnostic criterion or known biomarker reliably differentiates inflammatory lesions from neoplastic lymphoproliferations in the intestinal tract of cats and a diagnosis currently is established by integrating all available clinical and diagnostic data. Histopathology remains the mainstay to better differentiate LPE from LGITL in cats with chronic enteropathy.

Utility of fluorescence imitating brightfield imaging microscopy for the diagnosis of feline chronic enteropathy

Fluorescence imitating brightfield imaging (FIBI) is a novel microscopy method that allows for real-time, nondestructive, slide-free tissue imaging of fresh, formalin-fixed, or paraffin-embedded tissue. The nondestructive nature of the technology permits tissue preservation for downstream analyses. The objective of this observational study was to assess the utility of FIBI compared with conventional hematoxylin and eosin (H&E)-stained histology slides in feline gastrointestinal histopathology. Formalin-fixed paraffin-embedded full-thickness small intestinal tissue specimens from 50 cases of feline chronic enteropathy were evaluated. The ability of FIBI to evaluate predetermined morphological features (epithelium, villi, crypts, lacteals, fibrosis, submucosa, and muscularis propria) and inflammatory cells was assessed on a 3-point scale (0 = FIBI cannot identify the feature; 1 = FIBI can identify the feature; 2 = FIBI can identify the feature with more certainty than H&E). H&E and FIBI images were also scored according to World Small Animal Veterinary Association (WSAVA) Gastrointestinal Standardization Group guidelines. FIBI identified morphological features with similar or, in some cases, higher confidence compared with H&E images. The identification of inflammatory cells was less consistent. FIBI and H&E images showed an overall poor agreement with regard to the assigned WSAVA scores. While FIBI showed an equal or better ability to identify morphological features in intestinal biopsies, its ability to identify inflammatory cells is currently inferior compared with H&E-based imaging. Future studies on the utility of FIBI as a diagnostic tool for noninflammatory histopathologic lesions are warranted.

Canine chronic enteropathy—Current state-of-the-art and emerging concepts

Over the last decade, chronic inflammatory enteropathies (CIE) in dogs have received great attention in the basic and clinical research arena. The 2010 ACVIM Consensus Statement, including guidelines for the diagnostic criteria for canine and feline CIE, was an important milestone to a more standardized approach to patients suspected of a CIE diagnosis. Great strides have been made since understanding the pathogenesis and classification of CIE in dogs, and novel diagnostic and treatment options have evolved. New concepts in the microbiome-host-interaction, metabolic pathways, crosstalk within the mucosal immune system, and extension to the gut-brain axis have emerged. Novel diagnostics have been developed, the clinical utility of which remains to be critically evaluated in the next coming years. New directions are also expected to lead to a larger spectrum of treatment options tailored to the individual patient. This review offers insights into emerging concepts and future directions proposed for further CIE research in dogs for the next decade to come.

Association of fecal and serum microRNA profiles with gastrointestinal cancer and chronic inflammatory enteropathy in dogs

BACKGROUND

Reliable biomarkers to differentiate gastrointestinal cancer (GIC) from chronic inflammatory enteropathy (CIE) in dogs are needed. Fecal and serum microRNAs (miRNAs) have been proposed as diagnostic and prognostic markers of GI disease in humans and dogs.

HYPOTHESIS/OBJECTIVES

Dogs with GIC have fecal and serum miRNA profiles that differ from those of dogs with CIE.

AIMS

(a) identify miRNAs that differentiate GIC from CIE, (b) use high-throughput reverse transcription quantitative real-time PCR (RT-qPCR) to establish fecal and serum miRNA panels to distinguish GIC from CIE in dogs.

ANIMALS

Twenty-four dogs with GIC, 10 dogs with CIE, and 10 healthy dogs, all client-owned.

METHODS

An international multicenter observational prospective case-control study. Small RNA sequencing was used to identify fecal and serum miRNAs, and RT-qPCR was used to establish fecal and serum miRNA panels with the potential to distinguish GIC from CIE.

RESULTS

The best diagnostic performance for distinguishing GIC from CIE was fecal miR-451 (AUC: 0.955, sensitivity: 86.4%, specificity: 100%), miR-223 (AUC: 0.918, sensitivity: 90.9%, specificity: 80%), and miR-27a (AUC: 0.868, sensitivity: 81.8%, specificity: 90%) and serum miR-20b (AUC: 0.905, sensitivity: 90.5%, specificity: 90%), miR-148a-3p (AUC: 0.924, sensitivity: 85.7%, specificity: 90%), and miR-652 (AUC: 0.943, sensitivity: 90.5%, specificity: 90%). Slightly improved diagnostic performance was achieved when combining fecal miR-451 and miR-223 (AUC: 0.973, sensitivity: 95.5%, specificity: 90%).

CONCLUSIONS AND CLINICAL IMPORTANCE

When used as part of a diagnostic RT-qPCR panel, the abovementioned miRNAs have the potential to function as noninvasive biomarkers for the differentiation of GIC and CIE in dogs.

Serum metabolomic profiles in dogs with chronic enteropathy

BACKGROUND

Metabolic profiles differ between healthy humans and those with inflammatory bowel disease. Few studies have examined metabolic profiles in dogs with chronic enteropathy (CE).

HYPOTHESIS

Serum metabolic profiles of dogs with CE are significantly different from those of healthy dogs.

ANIMALS

Fifty-five dogs with CE and 204 healthy controls.

METHODS

A cross-sectional study. The serum concentrations of 99 metabolites measured using a canine-specific proton nuclear magnetic resonance spectroscopy platform were studied. A 2-sample unpaired t-test was used to compare the 2 study samples. The threshold for significance was set at P < .05 with a Bonferroni correction for each metabolite group.

RESULTS

Nineteen metabolites and 18 indices of lipoprotein composition were significantly different between the CE and healthy dogs. Four metabolites were significantly higher in dogs with CE, including phenylalanine (mean and SD) (healthy: 0.0417 mmol/L; [SD] 0.0100; CE: 0.0480 mmol/L; SD: 0.0125; P value: <.001) and lactate (healthy: 1.8751 mmol/L; SD: 0.7808; CE: 2.4827 mmol/L; SD CE: 1.4166; P value: .003). Fifteen metabolites were significantly lower in dogs with CE, including total fatty acids, and glycine (healthy: 0.2273 mmol/L; SD: 0.0794; CE: 0.1828 mmol/L; SD CE: 0.0517; P value: <.001).

CONCLUSIONS AND CLINICAL IMPORTANCE

The metabolic profile of dogs with CE is significantly different from that of healthy dogs, this opens novel research avenues to develop better diagnostic and prognostic approaches as well as therapeutic trials.

Evaluation of a Probability-Based Predictive Tool on Pathologist Agreement Using Urinary Bladder as a Pilot Tissue

Simple Summary

There is a common joke in pathology—put three pathologists in a room and you will obtain three different answers. This saying comes from the fact that pathology can be subjective; pathologists’ diagnoses can be influenced by many different biases, and pathologists are also influenced by the presence or absence of animal information and medical history. Compared to pathology, statistics is a much more objective field. This study aimed to develop a probability-based tool using statistics obtained by analyzing 338 histopathology slides of canine and feline urinary bladders, then see if the tool affected agreement between the test pathologists. Four pathologists diagnosed 25 canine and feline bladder slides and they conducted this three times: without animal and clinical information, then with this information, and finally using the probability tool. Results showed large differences in the pathologists’ interpretation of bladder slides, with kappa agreement values (low value for digital slide images, high value for glass slides) of 7–37% without any animal or clinical information, 23–37% with animal signalment and history, and 31–42% when our probability tool was used. This study provides a starting point for the use of probability-based tools in standardizing pathologist agreement in veterinary pathology.

Abstract

Inter-pathologist variation is widely recognized across human and veterinary pathology and is often compounded by missing animal or clinical information on pathology submission forms. Variation in pathologist threshold levels of resident inflammatory cells in the tissue of interest can further decrease inter-pathologist agreement. This study applied a predictive modeling tool to bladder histology slides that were assessed by four pathologists: first without animal and clinical information, then with this information, and finally using the predictive tool. All three assessments were performed twice, using digital whole-slide images (WSI) and then glass slides. Results showed marked variation in pathologists’ interpretation of bladder slides, with kappa agreement values of 7–37% without any animal or clinical information, 23–37% with animal signalment and history, and 31–42% when our predictive tool was applied, for digital WSI and glass slides. The concurrence of test pathologists to the reference diagnosis was 60% overall. This study provides a starting point for the use of predictive modeling in standardizing pathologist agreement in veterinary pathology. It also highlights the importance of high-quality whole-slide imaging to limit the effect of digitization on inter-pathologist agreement and the benefit of continued standardization of tissue assessment in veterinary pathology.

Histopathologic, phenotypic, and molecular criteria to discriminate low-grade intestinal T-cell lymphoma in cats from lymphoplasmacytic enteritis

BACKGROUND

Differentiation of low-grade intestinal T-cell lymphoma (LGITL) from lymphoplasmacytic enteritis (LPE) in cats is a diagnostic challenge for pathologists.

OBJECTIVE

Characterize histologic, immunohistochemical, and molecular features of LGITL and LPE.

ANIMALS

Forty-four client-owned cats, 22 diagnosed with LGITL and 22 with LPE.

METHODS

Prospective, cohort study. Clinical suspicion of LGITL or LPE was based on persistent gastrointestinal signs, unresponsive to empirical treatments. All cats underwent a standardized diagnostic evaluation, including biopsy (preferentially full-thickness), and were diagnosed with LGITL or LPE after review of clinical, laboratory, sonographic, histologic, immunohistochemical, and clonality results.

RESULTS

A monomorphic lymphocytic population (22/22, 100%) and in-depth mucosal infiltration (15/22, 68%) were hallmarks of LGITL. Epithelial patterns (nests and plaques) were significantly more frequent in LGITL (11/22, 50%) than in LPE (1/22, 5%) cases (P = .001). A CD3+ lymphocytic apical-to-basal gradient was observed in 9/22 (41%) of LGITL vs 1/22 (5%) of LPE cases (P = .004). Most LPE cases (17/18, 94%) featured marked fibrosis in the superficial part of the lamina propria. The Ki-67 20%- and 30%-thresholds discriminated between LGITL and LPE within both the epithelium (specificity >95%) and lamina propria (specificity >95%), respectively. All LGITL cases were CD3+ pSTAT3- and pSTAT5+. T-cell receptor gamma chain gene rearrangements indicated monoclonality in 86% of LGITL cases. Surprisingly, 70% of LPE cases featured monoclonality (40%) or monoclonality on a polyclonal background (30%).

CONCLUSIONS AND CLINICAL IMPORTANCE

We identified new histologic, immunohistochemical, and clonality criteria to distinguish LGITL from LPE.

[Chronic enteropathies in cats - diagnostic and therapeutic approach]

Chronic enteropathies are characterized by persistent or recurrent gastrointestinal signs including vomiting, diarrhoea, weight loss, anorexia and lethargy for a minimum duration of 3 weeks. Diagnosis is by excluding other disease processes and includes faecal examinations, blood screenings (e. g., thyroidal, pancreatic, liver dysfunctions, investigation for infectious diseases, vitamin B₁₂ status), diagnostic imaging, histopathological evaluation using biopsies from several different gastrointestinal segments and the response to therapeutic trials. Chronic inflammatory enteropathies are classified as food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), immunosuppressant-responsive or, similarly -refractory enteropathy (IRE). Small-cell (low-grade) alimentary lymphoma (LGAL), a crucial differential diagnosis, is predominantly seen in older cats. The feline chronic enteropathy activity index (FCEAI), a clinical scoring system, was established to objectively assess the severity of clinical illness and to evaluate the response to treatment. In general, the prognosis depends on the underlying aetiology. Cats diagnosed with FRE typically have a good long-term prognosis with adequate dietary management. The response to treatment varies in cats with IRE, with same cats experiencing frequent relapses of clinical signs and still others being non-responsive to treatment. Prognosis for LGAL, with adequate treatment, is usually fair to good (median survival time 510-704 days).

Clinical signs, duodenal histopathological grades, and serum high-mobility group box 1 concentrations in dogs with inflammatory bowel disease

Background

Inflammatory bowel disease (IBD) commonly occurs in dogs, but there is lack of information about potential biomarkers of clinical and histopathologic severity.

Objective

To examine the role of serum C‐reactive protein (CRP) and high‐mobility group box 1 (HMGB1) concentrations in dogs with IBD.

Animals

Seventeen dogs with IBD and 25 healthy dogs.

Methods

In this prospective study, duodenal histopathologic severity was graded, and the clinical severity of IBD was assessed by the canine IBD assessment index (CIBDAI) score in dogs with IBD. Serum CRP and HMGB1 concentrations were compared between IBD and healthy dogs and analyzed according to histopathologic grade in dogs with IBD. The correlations between serum CRP and HMGB1 concentrations and the CIBDAI score were evaluated.

Results

Dogs with IBD had higher serum CRP (median [range] = 20.39 [1.53‐67.69] μg/mL vs 2.31 [0.17‐11.49] μg/mL; P < .001) and HMGB1 concentrations (0.44 [0.07‐1.58] ng/mL vs 0.05 [0.01‐0.25] ng/mL; P < .001) than healthy dogs. The serum HMGB1 concentration was higher in IBD dogs with a moderate to severe histopathologic grade (0.51 [0.30‐1.58] ng/mL, P = .03) than in those with a mild histopathologic grade (0.17 [0.07‐0.75] ng/mL). Serum CRP concentrations and CIBDAI score were positively correlated in dogs with IBD (r_s = .49, P = .05).

Conclusions and Clinical Importance

Serum HMGB1 could be a potential biomarker for diagnosing IBD and might be indicative of histopathologic severity in dogs, whereas serum CRP might be an indicator of clinical severity.

Circulating Endocannabinoids as Diagnostic Markers of Canine Chronic Enteropathies: A Pilot Study

Chronic enteropathies (CEs) in dogs, according to the treatment response to consecutive trials, are classified as food-responsive (FRE), antibiotic-responsive (ARE), and immunosuppressive-responsive (IRE) enteropathy. In addition to this classification, dogs with loss of protein across the gut are grouped as protein-losing enteropathy (PLE). At present, the diagnosis of CEs is time-consuming, costly and sometimes invasive, also because non-invasive biomarkers with high sensitivity and specificity are not yet available. Therefore, this study aimed at assessing the levels of circulating endocannabinoids in plasma as potential diagnostic markers of canine CEs. Thirty-three dogs with primary chronic gastrointestinal signs presented to Veterinary Teaching Hospitals of Teramo and Bologna (Italy) were prospectively enrolled in the study, and 30 healthy dogs were included as a control group. Plasma levels of N-arachidonoylethanolamine (AEA), 2-arachidonoylglycerol (2-AG), N-palmitoylethanolamine (PEA), and N-oleoylethanolamine (OEA) were measured at the time of the first visit in dogs with different CEs, as well as in healthy subjects. Plasma levels of 2-AG (p = 0.001) and PEA (p = 0.008) were increased in canine CEs compared to healthy dogs. In particular, PEA levels were increased in the FRE group compared to healthy dogs (p = 0.04), while 2-AG was higher in IRE than in healthy dogs (p = 0.0001). Dogs affected by FRE also showed decreased 2-AG (p = 0.0001) and increased OEA levels (p = 0.0018) compared to IRE dogs. Moreover, dogs with PLE showed increased 2-AG (p = 0.033) and decreased AEA (p = 0.035), OEA (p = 0.016) and PEA (p = 0.023) levels, when compared to dogs affected by CEs without loss of proteins. The areas under ROC curves for circulating 2-AG (0.91; 95% confidence interval [CI], 0.79–1.03) and OEA (0.81; 95% CI, 0.65–0.97) showed a good accuracy in distinguishing the different forms of CEs under study (FRE, ARE and IRE), at the time of the first visit. The present study demonstrated that endocannabinoid signaling is altered in canine CEs, and that CE subtypes showed distinct profiles of 2-AG, PEA and OEA plasma levels, suggesting that these circulating bioactive lipids might have the potential to become candidate biomarkers for canine CEs.

Prospective evaluation of a change in dietary therapy in dogs with steroid-resistant protein-losing enteropathy

OBJECTIVE

To describe the clinical effect of dietary alteration as a sole change to therapy in dogs with steroid-resistant protein-losing enteropathy.

MATERIALS AND METHODS

Prospective study. Eligible enrolled dogs received dietary alteration as sole change to their therapeutic plan. Canine Chronic Enteropathy Clinical Activity Index and serum albumin were monitored for the 3-month study period. Long-term follow-up data were also available for some of the study participants.

RESULTS

Fifteen dogs were eligible for enrollment over the study period. Twelve were enrolled, 10 remained in the study at 30 days, nine completed the 3-month study period. Following dietary alteration, eight of 10 dogs achieved complete remission, one dog achieved partial remission and one dog had no response. Seven of eight dogs achieving complete remission have remained in remission up to 4 years following study. In dogs with complete remission, median Canine Chronic Enteropathy Clinical Activity Index score was 11.5 and 4, and median serum albumin concentration was 15 g/L and 26 g/L at 0 and 14-28 days, respectively.

CLINICAL SIGNIFICANCE

Dogs with protein-losing enteropathy with previous lack of response to a combination of dietary therapies, glucocorticoids and immunosuppressive medications can achieve remission following a dietary change. Improvement is likely to be seen within 14 to 30 days. A change in dietary approach may be an alternative to further immunosuppression or anti-inflammatory strategies in some dogs with difficult to treat protein-losing enteropathy.

Differentiating Inflammatory Bowel Disease from Alimentary Lymphoma in Cats: Does It Matter?

Differentiation of feline inflammatory bowel disease and intestinal small cell lymphoma can be challenging, and some clinicians argue that it is unnecessary because prognosis and treatment are similar. Differentiation of feline inflammatory bowel disease and intestinal small cell lymphoma can be challenging and some clinicians argue that it is unnecessary since prognosis and treatment are similar. Altough the body of research on this topic has increased over time, we still know little about etiopathogenesis, progression, alternative treatment modalities and prognosis of the different forms of FCE. While differentiating IBD from SCL might not alter a single patients' disease course, further research efforts are required to alter the disease course for our feline patient population as a whole.

Feline chronic enteropathy

Feline chronic enteropathy is a common disorder, especially in the senior cat population, with rising incidence over the past decade. Feline chronic enteropathy is considered an umbrella term comprising different diseases including food-responsive enteropathy, idiopathic inflammatory bowel disease and alimentary small cell lymphoma. However, differentiation between those diseases is often difficult in practice. This review will discuss the clinical approach to cats with chronic enteropathy, state-of-the-art diagnostic tests and pitfalls thereof as well as current therapeutic approaches. Although, much of the etiopathogenesis is still unknown, increased research efforts in this field have brought new insights into diagnostic and therapeutic options for these cats.

Comparative Evaluation of the Cytological, Histopathological and Immunohistochemical Findings of Canine Cutaneous and Subcutaneous Masses

In this study, we compared the cytological, histopathological, and immunohistochemical diagnoses of 71 canine cutaneous and subcutaneous masses. Cytological diagnoses included 56 tumors (21 mesenchymal, 15 epithelial, 16 round cell, four melanocytic), 13 inflammatory reactions, and two cysts. Of the 21 cytologically diagnosed mesenchymal tumors, three were later confirmed non-tumoral (hematoma, granulation tissue, fibroepithelial polyp). Thirteen out of 15 epithelial tumors were correctly diagnosed cytologically, whereas two cases were confirmed to be non-tumoral (fibroepithelial polyp, granulation tissue) after histopathological examination. One mast cell tumor was later confirmed as fibrous hyperplasia; diagnoses were correct in other round cell tumors. Cytological diagnoses were correct for all melanocytic tumors and cystic lesions. Five cases which had been cytologically diagnosed as inflammatory reactions were diagnosed as tumors (lymphoma, papilloma, sebaceous adenoma, and squamous cell carcinoma) after histopathological examination. Immunohistochemistry confirmed the histopathological diagnoses of all epithelial and round cell tumors, while the diagnoses of six mesenchymal tumors were changed after the immunohistochemical examination. The total accuracy of cytology in the diagnosis of tumoral/non-tumoral masses was 84.5%, and the accuracy in the determination of benign/malignant behavior was 83%. Diagnostic accordance between histopathology and immunohistochemistry was 86.6%. High success rates obtained with cytological diagnoses prove that cytology is a reliable diagnostic tool. The main diagnostic challenge remains with mesenchymal tumors and tumors accompanied by inflammatory reactions. The results suggest that immunohistochemistry is fundamental for diagnoses of most mesenchymal tumors.

Blood neutrophil-to-lymphocyte ratio (NLR) as a diagnostic marker in dogs with chronic enteropathy

Few routinely available biomarkers are clinically useful in assessing dogs with chronic enteropathy (CE) and aid in CE subclassification. The diagnostic potential of the blood neutrophil-to-lymphocyte ratio (NLR) has not been evaluated in canine CE. We evaluated the NLR in 93 dogs with CE (no steroid treatment for ≥2 wk prior) and tested for an association with clinical, clinicopathologic, and histologic characteristics and also with CE subclassification. NLR was significantly higher in CE dogs with severe clinical disease than dogs with mild clinical disease (p = 0.047). Hypoalbuminemia (p < 0.001), but not hypocobalaminemia, was associated with higher NLRs. NLR was correlated with fecal alpha₁-proteinase inhibitor concentrations (ρ = 0.47) and the serum-to-fecal alpha₁-proteinase inhibitor ratio (ρ = -0.48; both p < 0.001) but not with serum or fecal inflammatory markers nor with the overall histologic score (all p > 0.05). Dogs with steroid- or other immunosuppressant-responsive (IRE) or nonresponsive enteropathy (NRE) had significantly higher NLRs (median: 7.3) than dogs with food-responsive enteropathy (FRE; median: 3.0; p = 0.003), and a NLR ≥5.5 best distinguished both groups of dogs. No difference in NLR was detected between dogs with IRE and dogs diagnosed with NRE. These findings suggest that leukogram changes (i.e., NLR) could be clinically useful in canine CE, and that neutrophils might play a role in the systemic inflammatory response associated with canine CE. The NLR can be easily assessed on routine hematology and can potentially aid in the subclassification of dogs with CE based on the response to treatment.

Comprehensive comparison of upper and lower endoscopic small intestinal biopsy in cats with chronic enteropathy

Background

Integrating immunohistochemistry (IHC) and clonality testing with histopathology may improve the ability to differentiate inflammatory bowel disease (IBD) and alimentary small cell lymphoma (LSA) in cats.

Hypothesis/Objectives

To evaluate the utility of histopathology, IHC, and clonality testing to differentiate between IBD and LSA and agreement of diagnostic results for endoscopic biopsy (EB) samples from the upper (USI) and lower small intestine (LSI).

Animals

Fifty‐seven cats with IBD or LSA.

Methods

All cases were categorized as definitive IBD (DefIBD), possible LSA (PossLSA), probable LSA (ProbLSA), or definitive LSA (DefLSA) based on histopathology alone. Results from IHC and clonality testing were integrated.

Results

Based on histopathology alone, 24/57 (42.1%), 15/57 (26.3%), and 18/57 (31.6%) cats were diagnosed with DefIBD, PossLSA or ProbLSA, and DefLSA, respectively. After integrating IHC and clonality testing, 11/24 cases (45.8%) and 15/15 cases (100%) previously categorized as DefIBD and PossLSA or ProbLSA, respectively, were reclassified as LSA. A final diagnosis of IBD and LSA was reported in 13/57 (22.8%) and 44/57 (77.2%) cats, respectively. Agreement between USI and LSI samples was moderate based on histopathology alone (κ = 0.66) and after integrating IHC and clonality testing (κ = 0.70). However, only 1/44 (2.3%) of the LSA cases was diagnosed based on LSI biopsy alone.

Conclusions and Clinical Importance

Integrating IHC and clonality testing increased the number of cases diagnosed with LSA, but the consequence for patient outcome is unclear. There was moderate agreement between USI and LSI samples. Samples from the LSI rarely changed the diagnosis.

Correlation of minimally invasive imaging techniques to assess intestinal mucosal perfusion with established markers of chronic inflammatory enteropathy in dogs

Background

Minimally invasive diagnostic imaging techniques to detect intestinal inflammation in dogs are lacking. Contrast‐enhanced ultrasound (CEUS) and endoscopic narrow band imaging‐like endoscopy (Storz Professional Image Enhancement System [SPIES]) might allow quantification of intestinal mucosal perfusion and microvessel density in chronic inflammatory enteropathy (CIE) of dogs.

Hypothesis/Objectives

Markers of mucosal perfusion as determined by CEUS and SPIES endoscopy are potentially useful diagnostic markers to help characterize CIE and correlate with histological inflammation type and severity.

Animals

Thirty client‐owned dogs diagnosed with CIE at a referral hospital were prospectively enrolled.

Materials and Methods

Data from CEUS, SPIES, and white light (WL) endoscopy were correlated with World Small Animal Veterinary Association (WSAVA) endoscopy and histology scores and vessel density as determined by immunohistochemistry for von Willebrand factor (vWF). Automated linear modeling was used to determine predictors of endoscopic and histologic severity.

Results

Duodenal histology correlated with SPIES data (area percentage value, rho = 0.424, P = .04). White light endoscopy parameters correlated with SPIES parameters in the duodenum. Colonic histology correlated positively with CEUS, whereas colonic CEUS parameters correlated inversely with vWF expression. Several duodenal parameters combined predicted duodenal histology scores to a level of 73.4%. For the colon, 2 parameters contributed more than others to 73.1%.

Conclusion and Clinical Importance

Minimally invasive CEUS and SPIES appear feasible to assess intestinal perfusion in CIE. Use of SPIES endoscopy may be promising for assessing small intestinal inflammation, whereas CEUS could be used to assess colonic perfusion and inflammation. Both techniques need to be investigated further for their clinical utility.

Retrospective assessment of the clinical relevance of surgical biopsies of abdominal lymph nodes in cats: 51 cases (2014-2018)

OBJECTIVES

The aims of this study were to assess surgical biopsy of abdominal lymph nodes (LNs) in cats taken at the time of exploratory laparotomy and to evaluate any additional benefit of histopathology compared with LN cytology.

METHODS

We carried out a retrospective study from a single institution of cats that had abdominal ultrasound and LN biopsies as part of an exploratory laparotomy (2014-2018). Clinical records were reviewed for presenting signs, medical investigations, ultrasound, cytology, surgical findings and histopathology.

RESULTS

Fifty-one cats were included. In total, 60 LNs were biopsied. Forty-four cats had evident LN enlargement at the time of surgery. Nine of those cases were reported to have normal-sized LNs on ultrasound, including one cat that was subsequently diagnosed with lymphoma. Ultrasound-guided LN aspiration was performed in 19 cases. Five of these cats had a histological diagnosis of neoplasia following biopsy, but only one was correctly identified with cytology. Histopathology results were reactive hyperplasia (n = 41), tumour metastasis (n = 11), lymphadenitis (n = 6), inconclusive (n = 1) and normal (n = 1). The most common final diagnoses were inflammatory bowel disease (n = 17/51) and gastrointestinal lymphoma (n = 10/51). There were 15 cats with neoplastic disease; LN biopsies confirmed metastatic disease in 10 and ruled out nodal involvement in five.

CONCLUSIONS AND RELEVANCE

Surgical biopsy of grossly enlarged or normal abdominal LNs provides additional information to LN cytology in cats and in the majority of cases is associated with a positive histological diagnosis. There appears to be the potential to underdiagnose neoplasia with cytology alone.

Endoscopic Biopsies and Histopathological Findings in Diagnosing Chronic Gastrointestinal Disorders in Dogs and Cats

Nowadays, endoscopic examination is a diagnostic tool gaining popularity in the management of gastrointestinal disorders in dogs and cats. Direct accessibility of the lumen of gastrointestinal tract combined with the mucosal biopsy provides a great diagnostic potential. Using endoscopy and endoscopically guided biopsy, one can conduct both macro- and microscopic assessment of lesions and perform many specialist adjunct examinations. Histopathological examination of mucosal biopsy specimens collected from the stomach and intestines allows us to distinguish between types of inflammations and to diagnose ulcerative, polypoid, and cancerous lesions.

Comparison of clinical, endoscopic, and histologic features between dogs with chronic gastritis with and without lymphofollicular hyperplasia

OBJECTIVE

To compare clinical, endoscopic, and histopathologic features between dogs with chronic gastritis (CG) with and without lymphofollicular hyperplasia (LFH).

ANIMALS

64 and 56 dogs with CG with (cases) and without (controls) LFH, respectively.

PROCEDURES

The medical record database of a referral clinic was searched to identify dogs that underwent endoscopic examination of the upper portion of the gastrointestinal tract and were subsequently determined to have CG with or without LFH between October 2006 and February 2011. Signalment and clinical, endoscopic, and histologic findings were compared between cases and controls. Logistic regression was used to identify factors associated with CG with LFH.

RESULTS

Compared with controls, cases were significantly younger and more likely to be of a brachycephalic phenotype. The proportions of dogs with a poor body condition or diarrhea were significantly lower and the proportions of dogs with inspiratory dyspnea, exercise intolerance, or hyperemia and discoloration of the gastric mucosa were significantly higher for the case group, compared with the control group. Inspiratory dyspnea, gastric mucosal hyperemia, and gastritis severity were positively associated, whereas poor body condition was negatively associated, with CG with LFH on multivariable logistic regression.

CONCLUSIONS AND CLINICAL RELEVANCE

The strong positive association between inspiratory dyspnea and CG with LFH suggested that the condition may be a consequence of an increase in negative intrathoracic pressure rather than a distinct clinical entity. Prospective studies are warranted to elucidate the mechanism by which inspiratory dyspnea contributes to the development of CG with LFH.

A modified Sydney system for the diagnosis of chronic gastritis in dogs

Background

The Sydney system for assessing inflammatory lesions in the gastric mucosa is based on endoscopic and histological examinations. This study aimed to apply the Sydney system to diagnose gastritis in dogs. The study also compared the results of endoscopic and histological examinations conducted on gastric mucosal biopsy specimens. A total of 56 dogs with chronic vomiting were analyzed in the study. The physical appearance of the gastric mucosa was assessed through endoscopic examination, while the severity of the gastric inflammation, inflammation activity, glandular atrophy, and intestinal metaplasia were assessed by histopathological examination.

Results

The endoscopic examination confirmed the presence of inflammatory lesions affecting the gastric corpus and pylorus in all the dogs, although the severity of these lesions differed between the individuals. Reflux gastritis was the most commonly observed gastric inflammation. In the histopathological examination of the gastric mucosal samples, inflammatory lesions were found in the gastric corpus of 53 dogs, while 55 dogs had lesions in the pylorus. This corresponds to a 96.4% agreement between the methods.

Conclusions

The Sydney system is a useful tool for macroscopic and microscopic assessment of changes in the gastric mucosa as it enables the determination of inflammation type and severity, which helps the canine gastroenterologists to reliably compare the results of the tests performed in different facilities. Besides, the use of the Sydney system in diagnosing lesions facilitates the selection and effective monitoring of treatment. However, despite a high rate of agreement between the results of endoscopic and histopathological examinations, it is recommended to use both these methods for the assessment of the gastric mucosa in dogs.

Triaditis: Truth and Consequences

Clinical findings with triaditis and individual disease components overlap and may include hyporexia, weight loss, lethargy, vomiting, diarrhea, dehydration, icterus, abdominal pain, thickened bowel loops, pyrexia, dyspnea, and shock. A definitive diagnosis of triaditis requires histologic confirmation of inflammation in each organ, but this may not be possible because of financial or patient-related constraints. Evidence-based data indicate that histologic lesions of triaditis are present in 30% to 50% of cats diagnosed with pancreatitis and cholangitis/inflammatory liver disease. Treatment of triaditis is based on the overall health status of the patient and the type and severity of disease in component organs.

Proposed grading scheme for inflammatory bowel disease in ferrets and correlation with clinical signs

Inflammatory bowel disease (IBD) is an idiopathic, chronic, inflammatory disease of the gastrointestinal tract of companion animals, including ferrets (Mustela putorius furo). Clinical signs of IBD are nonspecific, and intestinal biopsies are necessary for a definitive diagnosis. A grading scheme has not been established for ferrets. Additionally, the association between histologic severity and clinical signs in ferrets is unknown. We evaluated enteric samples from ferrets diagnosed with IBD, compared histologic grading schemes, and correlated the results with the severity of clinical signs. Enteric sections from 23 ferrets with IBD were analyzed using grading schemes for intestinal inflammation in cats and dogs, and a correlation with clinical signs was evaluated. After dividing the histologic samples into groups based on the severity of clinical signs, main histologic differences were identified. Age and sex were also assessed for correlation with clinical signs. No significant correlation was found between the 2 grading schemes and clinical signs (rho = 0.02, p = 0.89; rho = 0.26, p = 0.18, respectively). Degree of villus fusion, hemorrhage and/or fibrin, epithelial damage, inflammation density, and crypt abscess formation were used retrospectively to create a ferret IBD grading scheme, which was significantly correlated with the severity of clinical signs (rho = 0.48, p = 0.01). A positive correlation was observed between age (p = 0.04) and females (p = 0.007) with severity of clinical signs. Our ferret grading scheme may have clinical utility in providing a more objective, consistent evaluation of IBD in ferrets.

Characterization of the fecal microbiome in cats with inflammatory bowel disease or alimentary small cell lymphoma

Feline chronic enteropathy (CE) is a common gastrointestinal disorder in cats and mainly comprises inflammatory bowel disease (IBD) and small cell lymphoma (SCL). Both IBD and SCL in cats share features with chronic enteropathies such as IBD and monomorphic epitheliotropic intestinal T-cell lymphoma in humans. The aim of this study was to characterize the fecal microbiome of 38 healthy cats and 27 cats with CE (13 cats with IBD and 14 cats with SCL). Alpha diversity indices were significantly decreased in cats with CE (OTU p = 0.003, Shannon Index p = 0.008, Phylogenetic Diversity p = 0.019). ANOSIM showed a significant difference in bacterial communities, albeit with a small effect size (P = 0.023, R = 0.073). Univariate analysis and LEfSE showed a lower abundance of facultative anaerobic taxa of the phyla Firmicutes (families Ruminococcaceae and Turicibacteraceae), Actinobacteria (genus Bifidobacterium) and Bacteroidetes (i.a. Bacteroides plebeius) in cats with CE. The facultative anaerobic taxa Enterobacteriaceae and Streptococcaceae were increased in cats with CE. No significant difference between the microbiome of cats with IBD and those with SCL was found. Cats with CE showed patterns of dysbiosis similar to those in found people with IBD.

Comparison of clinical, clinicopathologic, and histologic variables in dogs with chronic inflammatory enteropathy and low or normal serum 25-hydroxycholecalciferol concentrations

Background

The cause of low serum vitamin D concentrations in dogs with chronic inflammatory enteropathy (CIE) is not well understood.

Objective

Improve understanding of pathogenesis of low serum vitamin D concentrations in dogs with CIE by comparing several clinical, clinicopathologic, and histologic variables between CIE dogs with low and normal serum 25‐hydroxyvitamin D concentrations (25[OH]D).

Animals

Fifteen dogs with CIE and low serum 25[OH]D concentrations; 15 dogs with CIE and normal serum 25(OH)D concentrations.

Methods

Prospective cohort study. Clinical and clinicopathologic variables were compared between groups. Correlations between serum 25(OH)D concentration and histopathologic variables were assessed.

Results

Dogs with CIE and low serum 25(OH)D concentrations had higher canine chronic enteropathy clinical activity index scores (P = .003), lower serum α‐tocopherol (P < .001), cholesterol (P < .001), and albumin (P < .001) concentrations and higher serum C‐reactive protein (P = .004) concentrations compared to CIE dogs with normal serum 25(OH)D concentrations. Serum concentrations of vitamin D‐binding protein (VDBP) were not different between groups (P = .91). Duodenal morphologic and inflammatory histopathological scores (P = .002 and P = .004, respectively) and total histopathological scores in duodenum and combined duodenum and ileum negatively correlated with serum 25(OH)D concentration.

Conclusions and Clinical Importance

The pathogenesis of low serum vitamin D concentrations in dogs with CIE is likely multifactorial. Fat malabsorption deserves further study in dogs with low serum vitamin D concentration and CIE. Loss of VDBP does not appear to be an important cause of low serum vitamin D concentration in dogs with CIE.

Cytology and the cell block method in diagnostic characterization of canine lymphadenopathy and in the immunophenotyping of nodal lymphoma

Minimally invasive techniques used to evaluate canine peripheral lymphadenopathy (PLN), including fine needle aspiration biopsy with cytological evaluation (FNAB-C) and flow cytometry (FC), have benefits and limitations. The cell block (CB) method is an alternate processing technique in which fine needle aspirate biopsy samples are concentrated, fixed, and embedded in paraffin for routine histological processing/staining. Utilizing three observers, we determined the diagnostic value of the CB in evaluating canine PLN across six categories (non-diagnostic, reactive, inflammatory/infectious, probable lymphoma and lymphoma, metastatic neoplasia) and correlated findings to immunophenotypic and clonal antigen receptor rearrangement results in canine nodal lymphoma. Eighty-five paired FNAB-C and CB samples were evaluated from canine patients presenting to the University of Minnesota Veterinary Oncology or Internal Medicine services. Diagnostic quality samples were obtained in 55/85 (65%) CB and 81/85 (95%) FNAB-C samples, respectively, and nodal pathology impacted CB diagnostic yield. Overall percent agreement between diagnostic-quality FNAB-C and CB samples was 86%, but increased to 95% if the categories of lymphoma and probable lymphoma were combined. There was 100% agreement for both the diagnoses of metastatic neoplasia and reactive lymph nodes and 92% agreement for the diagnosis of lymphoma/probable lymphoma. Using immunohistochemistry (IHC), CB samples correctly immunophenotyped 22/23 (96%) cases of B-cell lymphoma, but only 1/6 (17%) cases of T-cell lymphoma. IHC was not completed on nine cases of lymphoproliferative disease because of insufficient cellularity. When the CB method (CBM) yielded diagnostic quality samples there was good to excellent agreement with FNAB-C samples and CB samples were suitable for some IHC tests.

Lymphatic endothelial cell immunohistochemical markers for evaluation of the intestinal lymphatic vasculature in dogs with chronic inflammatory enteropathy

Background

Lymphatic endothelial cell (LEC) immunohistochemical markers have identified intestinal lymphatic vasculature abnormalities in humans with inflammatory bowel disease, but have not been used to evaluate intestinal lymphatic vasculature in a group of dogs with chronic inflammatory enteropathy (CIE).

Objectives

To utilize LEC markers to identify and measure intestinal lymphatic vasculature in endoscopic biopsy samples of CIE dogs. To evaluate whether measured lymphatic vasculature variables correlate with serum albumin concentrations.

Animals

Twenty‐four dogs with CIE; n = 13, serum albumin concentration <2.5 g/dL (CIE‐protein‐losing enteropathy [PLE]), n = 11, serum albumin concentration ≥2.5 g/dL (CIE‐N).

Methods

Prospective study. Lymphatic endothelial cell immunolabeling with Prox‐1 and LYVE‐1 performed on endoscopic biopsy samples from 24 dogs with CIE. Duodenal and ileal villous lacteal width (VLW) and proprial mucosal lacteal width (MLW) were determined for each case and analyzed for correlation with serum albumin concentration. Lacteal dilatation scores using routine H&E histopathology were assessed for correlation with immunohistochemistry (IHC)‐calculated VLW and MLW.

Results

Lower serum albumin concentrations were correlated with increased VLW (rho = −.4644; P = .02) and MLW (rho = −.6514; P < .001) in the ileum. Lymphatic endothelial cell IHC identified presumptive proprial mucosal lymphangiectasia in some dogs that was not recognized with routine H&E staining. Lacteal dilatation scores were correlated with VLW in duodenum (rho = .4634; P = .02) and ileum (rho = .5292; P = .008), but did not correlate with MLW.

Conclusions and Clinical Importance

Lymphatic endothelial cell immunolabeling identified presumptive proprial mucosal lymphangiectasia in CIE dogs, particularly in the ileum of hypoalbuminemic dogs. Routine evaluation of villous lacteals likely underestimates abnormalities of the lymphatic vasculature in dogs with CIE.

Results of histopathology, immunohistochemistry, and molecular clonality testing of small intestinal biopsy specimens from clinically healthy client-owned cats

Background

Histopathology, immunohistochemistry, and molecular clonality testing are metrics frequently used to diagnose chronic enteropathy (CE) in cats. However, normal values for these metrics have been based mainly on samples from cats that were relatively young, specific pathogen‐free, or both.

Objectives

To describe results of histopathology, immunohistochemistry, and clonality testing of endoscopically‐derived biopsy specimens of the upper small intestinal tract from a cohort of clinically healthy client‐owned cats.

Animals

Twenty clinically healthy client‐owned cats ≥3 years of age.

Methods

Tissue specimens were collected from the stomach and duodenum and evaluated single blinded by a board‐certified pathologist. In addition, samples were evaluated by routine immunohistochemistry and clonality testing. Cats were followed after the procedure for signs of CE.

Results

Integrated results from histopathology, immunohistochemistry, and clonality testing were interpreted as consistent with small cell lymphoma (SCL; n = 12), emerging SCL (n = 1), lymphocytic enteritis (n = 6), and pseudoclonality (n = 1). On follow‐up, 3 cats eventually developed clinical signs of CE, of which 2 were euthanized 295 and 654 days post‐endoscopy. The remaining 17 cats did not show clinical signs of CE after a median of 709 days (range, 219‐869 days).

Conclusions and Clinical Importance

Intestinal biopsy specimens from clinically healthy client‐owned cats commonly had abnormal findings on histopathology, immunohistochemistry, clonality testing, or some combination of these without apparent clinical relevance. Current diagnostic metrics for diagnosing CE in cats may need modification to be applicable to the general population of cats.

Correlating Gastrointestinal Histopathologic Changes to Clinical Disease Activity in Dogs With Idiopathic Inflammatory Bowel Disease

Prior studies have failed to detect a convincing association between histologic lesions of inflammation and clinical activity in dogs with inflammatory bowel disease (IBD). We hypothesized that use of a simplified histopathologic scoring system would improve the consistency of interpretation among pathologists when describing histologic lesions of gastrointestinal inflammation. Our aim was to evaluate the correlation of histopathologic changes to clinical activity in dogs with IBD using this new system. Forty-two dogs with IBD and 19 healthy control dogs were enrolled in this retrospective study. Endoscopic biopsies from the stomach, duodenum, ileum, and colon were independently scored by 8 pathologists. Clinical disease activity was scored using the Canine Inflammatory Bowel Disease Activity Index (CIBDAI) or the Canine Chronic Enteropathy Clinical Activity Index (CCECAI), depending on the individual study center. Summative histopathological scores and clinical activity were calculated for each tissue (stomach, duodenum, ileum, and colon) and each tissue histologic score (inflammatory/morphologic feature). The correlation between CCECAI/CIBDAI and summative histopathologic score was significant ( P < .05) for duodenum ( r = 0.42) and colon ( r = 0.33). In evaluating the relationship between histopathologic scores and clinical activity, significant ( P < .05) correlations were observed for crypt dilation ( r = 0.42), lamina propria (LP) lymphocytes ( r = 0.40), LP neutrophils ( r = 0.45), mucosal fibrosis ( r = 0.47), lacteal dilation ( r = 0.39), and villus stunting ( r = 0.43). Compared to earlier grading schemes, the simplified scoring system shows improved utility in correlating histopathologic features (both summative histology scores and select histologic scores) to IBD clinical activity.

Comparison of standard single-bite with multiple-bite biopsy forceps for collection of gastrointestinal biopsies in dogs: a prospective study

Various types of endoscopic biopsy forceps have been investigated in dogs. The Multibite (MB) are multiple-bite forceps that collect up to four tissue specimens in a single pass through the endoscope, reducing procedure time. The authors prospectively investigated its clinical utility by comparing procedure times and diagnostic quality of samples obtained with the MB to that of biopsies performed with a single-bite forceps (SB), in 21 dogs with gastrointestinal disorders. When comparing the depth, crush artefacts and diagnostic adequacy of the gastric and duodenal biopsies, there was no significant difference between the MB and SB forceps. The procedure time was significantly longer with the MB. There was no learning curve effect, and there were no reported adverse events. This study failed to demonstrate any significant clinical advantage associated with the use of the Multibite forceps over that of conventional disposable SB forceps.

Feline low-grade alimentary lymphoma: an emerging entity and a potential animal model for human disease

BACKGROUND

Low-grade alimentary lymphoma (LGAL) is characterised by the infiltration of neoplastic T-lymphocytes, typically in the small intestine. The incidence of LGAL has increased over the last ten years and it is now the most frequent digestive neoplasia in cats and comprises 60 to 75% of gastrointestinal lymphoma cases. Given that LGAL shares common clinical, paraclinical and ultrasonographic features with inflammatory bowel diseases, establishing a diagnosis is challenging. A review was designed to summarise current knowledge of the pathogenesis, diagnosis, prognosis and treatment of feline LGAL. Electronic searches of PubMed and Science Direct were carried out without date or language restrictions.

RESULTS

A total of 176 peer-reviewed documents were identified and most of which were published in the last twenty years. 130 studies were found from the veterinary literature and 46 from the human medicine literature. Heterogeneity of study designs and outcome measures made meta-analysis inappropriate. The pathophysiology of feline LGAL still needs to be elucidated, not least the putative roles of infectious agents, environmental factors as well as genetic events. The most common therapeutic strategy is combination treatment with prednisolone and chlorambucil, and prolonged remission can often be achieved. Developments in immunohistochemical analysis and clonality testing have improved the confidence of clinicians in obtaining a correct diagnosis between LGAL and IBD. The condition shares similarities with some diseases in humans, especially human indolent T-cell lymphoproliferative disorder of the gastrointestinal tract.

CONCLUSIONS

The pathophysiology of feline LGAL still needs to be elucidated and prospective studies as well as standardisation of therapeutic strategies are needed. A combination of conventional histopathology and immunohistochemistry remains the current gold-standard test, but clinicians should be cautious about reclassifying cats previously diagnosed with IBD to lymphoma on the basis of clonality testing. Importantly, feline LGAL could be considered to be a potential animal model for indolent digestive T-cell lymphoproliferative disorder, a rare condition in human medicine.

Cyclooxygenase-2 immunoexpression in intestinal epithelium and lamina propria of cats with inflammatory bowel disease and low grade alimentary lymphoma

Background

Cyclooxygenase 2 (COX-2) is an inducible isoform by cellular activation, proinflammatory cytokines and growth factors. The aims of the current study were to evaluate COX-2 immunoexpression in epithelial and lamina propria (LP) of cats with inflammatory bowel disease (IBD) and low grade alimentary lymphoma (LGAL), as well as to correlate them with clinical signs and histopathological scoring. Cats diagnosed with IBD and LGAL (2007–2013) were included in the current study. Feline chronic enteropathy activity index (FCEAI) was calculated for all cases. Control group was composed by 3 healthy indoor cats and 5 sick cats died or were euthanized (non-gastrointestinal illness). Diagnosis and classification of IBD and LGAL was established according to the WSAVA gastrointestinal standardization group template and the National Cancer Institute formulation, respectively. Furthermore, a modified WSAVA template was applied for LGAL evaluation. Immunolabelling for COX-2 (polyclonal rabbit anti-murine antibody) was performed on biopsy samples. Epithelial and LP (inflammatory or neoplastic cells) COX-2 immunolabelling was calculated according to the grade and intensity. The most representative segment scored by the WSAVA and the modified WSAVA were used for statistical analysis.

Results

Significant difference was found regarding COX-2 intensity overexpression in the epithelial cells of IBD and LGAL groups when compared to control cats, but not between the groups of sick cats, whereas no differences were found regarding the grade of immunoreactivity between groups. No difference was found for COX-2 immunoexpression at the LP between all groups. However, 3 cats from LGAL group showed COX-2 expression in neoplastic cells at the LP. There were no correlations between epithelial or LP COX-2 expression and FCEAI and histological alterations.

Conclusions

Increased COX-2 intensity at the epithelial cells observed in cats with IBD and LGAL may be secondary to the inflammatory response or a protective function in the intestinal reparation. COX-2 expression at the LP was presented in 33% of LGAL. This result provides a reason for further investigation concerning the role of COX-2 expression in feline alimentary lymphoma.

Determining optimal therapy of dogs with chronic enteropathy by measurement of serum citrulline

Background

Serum concentration of citrulline is a useful biomarker in human intestinal disease and indicates globally reduced enterocyte mass and absorptive function in various disease states.

Objectives

To determine whether serum citrulline concentration is a biomarker in chronic enteropathy (CE) in dogs, to provide useful information regarding optimal treatment or to predict outcome.

Animals

Seventy‐four dogs with CE and 83 breed‐ and age‐matched hospital controls with no clinical signs of intestinal disease.

Methods

Retrospective study. Outcome was determined and dogs were categorized by response to treatment as having food‐responsive enteropathy (FRE), antibiotic‐responsive diarrhea (ARD), or idiopathic inflammatory bowel disease (IBD). Disease severity was quantified by the CIBDAI scoring index.

Results

Serum citrulline concentration did not differ between dogs with CE (median, 8.4 µg/mL, 5th‐95th percentile 2.0‐19.6) and controls (median, 8.1 µg/mL, 5th‐95th percentile 2.2‐19.7, P = .91). Serum citrulline concentration was similar between dogs with FRE (median, 9.1 µg/mL, 5th‐95th percentile 2.0‐18.9), ARD (median, 13.0 µg/mL, 5th‐95th percentile 1.6‐19.2), IBD (median, 8.4 µg/mL, 5th‐95th percentile 2.1‐21.0; P = .91). Serum citrulline did not correlate to CIBDAI or to serum albumin concentration.

Conclusions and Clinical Importance

In our study, serum citrulline concentration was not associated with efficacy of treatment or outcome in dogs with CE.

Significance of clonal rearrangements of lymphocyte antigen receptor genes on the prognosis of chronic enteropathy in 22 Shiba dogs

Shiba dogs are predisposed to chronic enteropathy (CE) and have poorer prognosis than other dog breeds. The objective of this study was to investigate the significance of polymerase chain reaction for antigen receptor rearrangement (PARR) results on clinical findings and prognosis of Shiba dogs with CE. We retrospectively collected data on 22 Shiba dogs diagnosed as having CE. Fifty-nine percent of the dogs had clonality-positive results on PARR analysis. Furthermore, on histopathology, epitheliotropic behavior of small lymphocytes of the intestinal mucosa was observed significantly more frequently in dogs with clonal rearrangement of antigen receptor genes (P=0.027). The median overall survival time of clonality-positive dogs was 48 days (range, 4–239 days), compared to 271 days (range, 45–1,316+ days) in clonality-negative dogs. The median overall survival time of epitheliotropism-positive dogs was 76 days (range, 30–349 days) compared to 239 days (range, 4–1,316+ days) for epitheliotropism-negative dogs. Statistical analysis revealed that the clonality-positive result was associated with significantly shorter survival time (P=0.036). In contrast, presence or absence of epitheliotropism had no statistically significant effect on survival time (P=0.223). These cases might appropriately be diagnosed as small T-cell intestinal lymphoma; there are some common clinical and pathogenic features with human enteropathy-associated T-cell lymphoma type 2. The pathogenesis and poor prognosis for Shiba dogs with CE seem to be associated with this type of lymphoma, although further investigation is warranted.

Evaluation of Serum 3-Bromotyrosine Concentrations in Dogs with Steroid-Responsive Diarrhea and Food-Responsive Diarrhea

Background

The clinical usefulness of serum 3‐BrY concentrations for subclassifying dogs with food‐responsive diarrhea (FRD) and steroid‐responsive diarrhea (SRD) has not been studied.

Hypothesis/Objectives

To compare serum 3‐BrY concentrations in dogs with FRD, dogs with SRD, and healthy control dogs.

Animals

38 dogs with FRD, 14 dogs with SRD, and 46 healthy dogs.

Methods

Prospective study. Measurement of 3‐BrY concentration in serum samples was performed by gas chromatography/mass spectrometry.

Results

There was no association of peripheral eosinophilia in dogs with FRD, SRD, and healthy control dogs (P = 0.069). There was no significant correlation between peripheral eosinophil counts and serum 3‐BrY concentrations (ρ = −0.15, P = 0.13). Serum 3‐BrY concentrations in dogs with SRD (median [range] = 3.27, 0.9–26.23 μmol/L) were significantly higher than in dogs with FRD (median [range] = 0.99, 0.62–8.82 μmol/L; P = 0.007) or in healthy dogs (median [range] = 0.62, 0.62–1.79 μmol/L; P < 0.001). Also, serum 3‐BrY concentrations in dogs with FRD were significantly higher than in healthy dogs (P = 0.025). There was no significant correlation between the canine chronic enteropathy clinical activity index and serum 3‐BrY concentrations (ρ = 0.17, P = 0.23).

Conclusions and Clinical Importance

Measurement of serum 3‐BrY concentrations, but not the peripheral eosinophil count, is helpful for detecting dogs with SRD and FRD.

Endoscopic Cytology for the Diagnosis of Chronic Enteritis and Intestinal Lymphoma in Dogs

Although cytology is a rapid diagnostic procedure in dogs, the cytologic criteria of endoscopic biopsies for chronic enteritis and intestinal lymphoma are not well defined. An immediate diagnosis using cytology would benefit patients by enabling prompt initiation of therapy. The objective of this study was to investigate the correlation between the results of endoscopic cytology and histopathology. In this study, 167 dogs with clinical signs of chronic gastrointestinal disease were included. On the basis of histopathology, the following diagnoses were determined: lymphocytic-plasmacytic enteritis in 93 dogs; eosinophilic enteritis in 5 dogs; small cell intestinal lymphoma in 45 dogs; and large cell intestinal lymphoma in 24 dogs. Two clinical pathologists retrospectively evaluated the endoscopic cytology of squash-smear preparations. The cytologic diagnoses of inflammation, small cell lymphoma, and large cell lymphoma were based on the severity of lymphocyte infiltration, the size of infiltrated lymphocytes, and eosinophil/mast cell infiltration. The clinical severity score was significantly increased along with the degree of lymphocyte infiltration evaluated by cytology. The cytologic diagnosis was in complete agreement with the histopathologic diagnosis in 136 of 167 (81.4%) cases. For the differentiation between enteritis and lymphoma, endoscopic cytology had a sensitivity of 98.6%, a specificity of 73.5%, a positive predictive value of 72.3%, and a negative predictive value of 98.6%. The log-rank test and Cox regression analysis showed that the results of cytology predicted the prognosis. These results suggest that endoscopic cytology is a useful technique to aid diagnosis of intestinal inflammation and lymphoma in dogs.

Interobserver Agreement Using Histological Scoring of the Canine Liver

Background

Grading schemes for the assessment of hepatic fibrosis and necroinflammatory activity in humans previously have been applied to dogs with chronic hepatitis. Interobserver agreement is a desirable characteristic for any histological scoring scheme.

Hypothesis/Objectives

To assess interobserver agreement associated with pathologists using a previously published histological scoring scheme to assess hepatic fibrosis and necroinflammatory activity in dogs and to compare fibrosis scores assigned to serial sections stained with hematoxylin & eosin (H&E) and picrosirius red.

Animals

Histological sections of liver from 50 dogs with variable degrees of hepatic fibrosis and necroinflammatory activity were selected from institutional tissue archives.

Methods

Six board‐certified veterinary anatomic pathologists assigned fibrosis and necroinflammatory activity scores to the histological sections. The multiuser kappa statistic was calculated to assess interobserver agreement. Fibrosis stage assigned to serial sections stained with picrosirius red and H&E was compared using the Wilcoxon signed‐rank test.

Results

Multiuser kappa statistics for assessment of fibrosis and necroinflammatory activity from H&E‐stained sections were 0.35 and 0.16, respectively. There was no difference in median fibrosis scores assigned to serial section stained with H&E and picrosirius red (P = .248).

Conclusions and Clinical Importance

There was fair interobserver agreement when pathologists assessed fibrosis and poor agreement when they assessed necroinflammatory activity. This suboptimal agreement must be taken into account by clinicians making decisions based on histology reports of the liver and in the design of studies evaluating these findings. To decrease this variability, ideally >1 pathologist should evaluate each section.

Comparison of routinely used intestinal biopsy forceps in dogs: an ex vivo histopathological approach

OBJECTIVES

To compare the quality of duodenal and ileal samples obtained with different biopsy forceps.

METHODS

Fifteen dogs were included in a prospective ex vivo study. After euthanasia, the duodenum and the ileum were sampled with four different forceps and evaluated according to a standardised scoring system. The biopsy forceps evaluated had alligator jaws or cups with smooth edge with or without a needle.

RESULTS

The global quality of the biopsies was better in the ileum that in the duodenum regardless of the biopsy forceps. Biopsy forceps with smooth edge including a needle resulted in fewer artefacts than biopsy forceps with smooth edge but no needle in both sites and those with alligator jaws without a needle provided deeper biopsies than those with smooth edge without a needle only in the duodenum. There was no effect of the biopsy forceps type on the size of the biopsies.

CLINICAL SIGNIFICANCE

Our findings may aid in choosing the appropriate type of forceps for intestinal biopsy.

Histopathologic Characteristics of Intestinal Biopsy Samples from Dogs With Chronic Inflammatory Enteropathy With and Without Hypoalbuminemia

Background

Previous studies have identified hypoalbuminemia as a risk factor for negative outcome in dogs with chronic enteropathy (CE), but it has not been determined whether histopathology differs between CE dogs with and without hypoalbuminemia.

Objective

To compare histopathologic findings in dogs with biopsy‐diagnosed inflammatory CE with and without hypoalbuminemia.

Animals

83 dogs that had intestinal biopsy performed between January 2010–July 2015. Dogs had signs compatible with CE of at least 3‐weeks' duration and no evidence of clinically relevant extra‐gastrointestinal (GI) disease or potential non‐GI causes of hypoalbuminemia. Dogs had primary diagnosis of inflammatory enteritis based on histopathology.

Methods

Dogs were grouped into CE with normoalbuminemia (CEN; serum albumin concentration ≥3.0 g/dL, N = 46) or chronic enteropathy with hypoalbuminemia (CEH; serum albumin concentration <3.0 g/dL, N = 37). A pathologist (SLP) blinded to the groups reviewed biopsy samples and applied the World Small Animal Veterinary Association scoring system to all samples.

Results

Intestinal biopsy samples from dogs in the CEH group were significantly more likely to display villous stunting, epithelial injury, crypt distension, and lacteal dilatation, and were more likely to have intraepithelial lymphocytes and lamina propria neutrophils than biopsy samples from dogs in the CEN group. Additionally, higher scores for each of the above listed histopathologic criteria were associated with a lower serum albumin concentration.

Conclusions and Clinical Importance

Histopathologic features of chronic inflammatory enteropathy differ between dogs that are hypo‐ versus normoalbuminemic. Additional work is needed to elucidate the clinical relevance of these differences.

Evaluation of supervised machine-learning algorithms to distinguish between inflammatory bowel disease and alimentary lymphoma in cats

Inflammatory bowel disease (IBD) and alimentary lymphoma (ALA) are common gastrointestinal diseases in cats. The very similar clinical signs and histopathologic features of these diseases make the distinction between them diagnostically challenging. We tested the use of supervised machine-learning algorithms to differentiate between the 2 diseases using data generated from noninvasive diagnostic tests. Three prediction models were developed using 3 machine-learning algorithms: naive Bayes, decision trees, and artificial neural networks. The models were trained and tested on data from complete blood count (CBC) and serum chemistry (SC) results for the following 3 groups of client-owned cats: normal, inflammatory bowel disease (IBD), or alimentary lymphoma (ALA). Naive Bayes and artificial neural networks achieved higher classification accuracy (sensitivities of 70.8% and 69.2%, respectively) than the decision tree algorithm (63%, p < 0.0001). The areas under the receiver-operating characteristic curve for classifying cases into the 3 categories was 83% by naive Bayes, 79% by decision tree, and 82% by artificial neural networks. Prediction models using machine learning provided a method for distinguishing between ALA–IBD, ALA–normal, and IBD–normal. The naive Bayes and artificial neural networks classifiers used 10 and 4 of the CBC and SC variables, respectively, to outperform the C4.5 decision tree, which used 5 CBC and SC variables in classifying cats into the 3 classes. These models can provide another noninvasive diagnostic tool to assist clinicians with differentiating between IBD and ALA, and between diseased and nondiseased cats.

Comparison of 3 Handling Techniques for Endoscopically Obtained Gastric and Duodenal Biopsy Specimens: A Prospective Study in Dogs and Cats

Background

Limited evidence exists in the literature regarding whether a specific mount is preferable to use for processing endoscopically obtained gastrointestinal biopsy specimens.

Hypothesis/Objectives

To compare 3 methods of handling endoscopically obtained gastrointestinal biopsy specimens from collection to laboratory processing and to determine if any technique produced superior results.

Animals

Twenty‐three dogs and cats presented for gastrointestinal signs.

Methods

Prospective study of dogs and cats presented with gastrointestinal signs to a veterinary teaching referral hospital which underwent upper gastrointestinal endoscopy. Biopsy specimens were taken from the stomach and duodenum and submitted to the laboratory using 3 techniques: mounted on a cucumber slice, mounted on a moisturized synthetic foam sponge, and floating free in formalin. The techniques were compared with regard to the specimens' width, orientation, presence of artifacts, and pathologist's confidence in diagnosis.

Results

Twenty‐three patients were included, with a total of 528 biopsies collected. Specimens on cucumber slice and on sponge were significantly wider (P < .001 and P = .001, respectively) compared to those floating free in formalin (mean width of 3.81 versus 3.31 and 2.52 mm, respectively). However, specimens on synthetic sponge had significantly fewer artifacts compared to those on cucumber slice (P = .05) and those floating free in formalin (P = .02). Confidence in the diagnosis also was superior with the sponge technique over floating free specimens (P = .002).

Conclusions and Clinical Importance

The use of mounted gastrointestinal biopsy specimens was superior over the use of specimens floating free in formalin. This technique improved the quality of the specimens and the pathologist's confidence in their histopathologic interpretation.

Retrospective Study on the Diagnostic Value of Full-Thickness Biopsies from the Stomach and Intestines of Dogs with Chronic Gastrointestinal Disease Symptoms

An evaluation of histologic findings in full-thickness biopsies from the gastrointestinal tract (GIT) from 64 dogs with chronic GIT disease symptoms was performed. In the majority of cases (38/64; 59%), intestinal lymphangiectasia and mucosal edema of unknown etiology were present. In 10 dogs (16%) an eosinophilic colitis, either alone or together with gastritis and/or enteritis, was found. In 5 dogs (8%) lymphocytic-plasmacytic enteritis or enterocolitis was diagnosed. Five dogs (8%) had an intestinal T-cell lymphoma. Samples from the remaining cases were histologically normal or did not allow for a final diagnosis. In contrast to reports about findings in endoscopic biopsies (which often are of varying quality or inadequate for diagnosis), in the majority of cases of this study, examination of full-thickness biopsies from the GIT allowed us to make a definitive histopathologic diagnosis. Furthermore, the study revealed that transmural biopsies are very helpful for diagnosing lymphoma.

Alterations of the Ileal and Colonic Mucosal Microbiota in Canine Chronic Enteropathies

Background

The intestinal microbiota is increasingly linked to the pathogenesis of chronic enteropathies (CE) in dogs. While imbalances in duodenal and fecal microbial communities have been associated with mucosal inflammation, relatively little is known about alterations in mucosal bacteria seen with CE involving the ileum and colon.

Aim

To investigate the composition and spatial organization of mucosal microbiota in dogs with CE and controls.

Methods

Tissue sections from endoscopic biopsies of the ileum and colon from 19 dogs with inflammatory bowel disease (IBD), 6 dogs with granulomatous colitis (GC), 12 dogs with intestinal neoplasia, and 15 controls were studied by fluorescence in situ hybridization (FISH) on a quantifiable basis.

Results

The ileal and colonic mucosa of healthy dogs and dogs with CE is predominantly colonized by bacteria localized to free and adherent mucus compartments. CE dogs harbored more (P < 0.05) mucosal bacteria belonging to the Clostridium-coccoides/Eubacterium rectale group, Bacteroides, Enterobacteriaceae, and Escherichia coli versus controls. Within the CE group, IBD dogs had increased (P < 0.05) Enterobacteriaceae and E. coli bacteria attached onto surface epithelia or invading within the intestinal mucosa. Bacterial invasion with E. coli was observed in the ileal and colonic mucosa of dogs with GC (P < 0.05). Dogs with intestinal neoplasia had increased (P < 0.05) adherent (total bacteria, Enterobacteriaceae, E. coli) and invasive (Enterobacteriaceae, E. coli, and Bacteroides) bacteria in biopsy specimens. Increased numbers of total bacteria adherent to the colonic mucosa were associated with clinical disease severity in IBD dogs (P < 0.05).

Conclusion

Pathogenic events in canine CE are associated with different populations of the ileal and colonic mucosal microbiota.