Pathologic and prognostic characteristics of splenomegaly in dogs due to fibrohistiocytic nodules: 98 cases

Mitotic activity: A systematic literature review of the assessment methodology and prognostic value in canine tumors

One of the most relevant prognostic indices for tumors is cellular proliferation, which is most commonly measured by the mitotic activity in routine tumor sections. The goal of this systematic review was to analyze the methods and prognostic relevance of histologically measuring mitotic activity that have been reported for canine tumors in the literature. A total of 137 articles that correlated the mitotic activity in canine tumors with patient outcome were identified through a systematic (PubMed and Scopus) and nonsystematic (Google Scholar) literature search and eligibility screening process. Mitotic activity methods encompassed the mitotic count (MC, number of mitotic figures per tumor area) in 126 studies, presumably the MC (method not specified) in 6 studies, and the mitotic index (MI, number of mitotic figures per number of tumor cells) in 5 studies. A particularly high risk of bias was identified based on the available details of the MC methods and statistical analyses, which often did not quantify the prognostic discriminative ability of the MC and only reported P values. A significant association of the MC with survival was found in 72 of 109 (66%) studies. However, survival was evaluated by at least 3 studies in only 7 tumor types/groups, of which a prognostic relevance is apparent for mast cell tumors of the skin, cutaneous melanoma, and soft tissue tumor of the skin and subcutis. None of the studies using the MI found a prognostic relevance. This review highlights the need for more studies with standardized methods and appropriate analysis of the discriminative ability to prove the prognostic value of the MC and MI in various tumor types. Future studies are needed to evaluate the influence of the performance of individual pathologists on the appropriateness of prognostic thresholds and investigate methods to improve interobserver reproducibility.

Splenic stromal sarcomas in dogs: Outcome and clinicopathological prognostic factors in 32 cases

Due to the low frequency and the changes in diagnostic techniques and terminology during the last few years, only little clinical information is available on splenic stromal sarcoma (SSS). This multi-institutional study aimed at gathering clinical cases of SSS in dogs and investigates their clinical behaviour, as well as analyse possible clinicopathological prognostic factors, including the use of adjuvant therapy. Dogs with a histologically confirmed SSS that underwent splenectomy were retrospectively included. To be included in the study, either FFPE tissue blocks or multiple tissue sections had to be available for histopathologic and immunohistochemical revision. Clinical and pathological variables, along with adjuvant therapy data, were collected. Cumulative incidence of metastatic disease was analysed through univariate and bivariate analyses. The impact of adjuvant chemotherapy on metastasis incidence and survival was assessed, considering an estimated propensity score. A total of 32 dogs were included. Among them, 22 developed metastases with an incidence of 37.5%, 59.38%, and 65.94% at 6, 12, and 24 months, respectively. Univariate analysis identified mitotic count, total scoring, and necrosis as prognostic factors. In bivariate analysis, mitotic count remained prognostic. The administration of adjuvant chemotherapy did not have an impact on metastasis incidence or survival time. The study found that dogs with SSSs are at high risk of metastasis, although a small subgroup may experience longer survival after splenectomy. Mitotic count was the only variable having a reliable prognostic impact. Adjuvant chemotherapy did not appear to decrease the incidence of metastasis or prolong survival in these dogs.

Clinicopathologic features and biologic behavior of canine splenic nodules with stromal, histiocytic and lymphoid components

The term fibrohistiocytic nodule has been discouraged in favor of specific pathologic entities, including complex nodular hyperplasia, splenic stromal sarcoma and histiocytic sarcoma. Nevertheless, the diagnosis of splenic lesions with mixed stromal, histiocytic and lymphoid components still remains a challenge due to lack of straightforward histologic criteria. Misestimation of the biologic behavior of these lesions may lead to detrimental consequences on the clinical management of patients. In this study, we retrospectively evaluated the clinicopathologic features and outcome of canine splenic nodular lesions with mixed components, to identify prognostic factors and histologic criteria of malignancy. Thirty-seven cases were included. Immunohistochemistry did not allow for further subclassification. Nine (24.3%) dogs died from disease-related causes after a median of 234 days (range, 48–1,247). One-, 2- and 3-year disease-specific survival rates were 80, 60, and 43%, respectively. When considering nodules with stromal cell atypia and at least one of mitotic count ≥9, presence of karyomegaly/multinucleated cells and lymphoid component <40%, half of these dogs died of disease-related causes with a median disease-specific survival time of 548 days (95% CI, 0-1216). In the remaining dogs, no disease-related death was reported (P < 0.001). Canine splenic nodular lesions with mixed stromal, histiocytic and lymphoid components and histologic criteria of malignancy may behave aggressively, leading to distant metastasis and death. In the absence of further criteria aiding their classification, and to better characterize their biologic behavior, we encourage the distinction of these complex splenic tumors from conventional sarcomas and histiocytic sarcomas.

Epidemiology and Survival of Dogs Diagnosed with Splenic Lymphoid Hyperplasia, Complex Hyperplasia, Stromal Sarcoma and Histiocytic Sarcoma

Canine splenic fibrohistiocytic nodules traditionally encompassed benign lymphoid hyperplasia, complex hyperplasia, and malignant fibrous histiocytoma. The latter has been recently re-classified into histiocytic sarcoma and stromal sarcoma. Reliable indicators of post-splenectomy survival and demographic factors predisposing to the four types of nodules are not completely understood. This study aims to estimate frequency, survival times, and identify risk factors of splenectomized dogs diagnosed with lymphoid hyperplasia, complex hyperplasia, histiocytic sarcoma, and stromal sarcoma using medical records containing histopathological diagnosis from the VetCompass Australia database (1989−2018), which collects demographic, and clinical information from veterinary clinics. Out of 693 dogs, 315 were diagnosed with fibrohistiocytic nodules, mostly lymphoid hyperplasia (169/693, 24.4%), followed by stromal sarcoma (59/693, 8.5%), complex hyperplasia (55/693, 7.9%), and histiocytic sarcoma (32/693, 4.6%). Dogs aged 8−10 years were more likely to be diagnosed with histiocytic or stromal sarcoma than lymphoid hyperplasia. Dogs diagnosed with lymphoid hyperplasia had a longer survival time than those with other diagnoses (median > 2 years). Dogs diagnosed with histiocytic sarcoma had longer survival times (median 349 days) than stromal sarcoma (median 166 days). Results suggest that knowledge of the type of splenic fibrohistiocytic nodule, patients’ age, and sex can be used to increase prognostic accuracy.

Canine Non-Angiogenic, Non-Myogenic Splenic Stromal Sarcoma: a Retrospective Clinicopathological Analysis and Investigation of Podoplanin as a Marker of Tumour Histogenesis

Splenic stromal sarcomas are rarely reported tumours that were previously grouped as non-angiomatous, non-lymphomatous mesenchymal neoplasms of the canine spleen. Highly variable survival times have been reported probably due to their heterogeneous nature. The purpose of this study was to assess the outcome and prognostic factors in dogs with splenic stromal sarcoma after treatment by splenectomy. Clinical data were collected retrospectively and histopathology was reviewed for 47 patients. Histological classification, based on morphology in haematoxylin and eosin-stained sections, in conjunction with immunolabelling of macrophage scavenger receptor-A (CD204), desmin, factor VIII-related antigen and smooth muscle actin ,yielded diagnoses of undifferentiated stromal sarcoma (n = 22), complex nodular hyperplasia (CNH, n = 9), sarcoma arising from benign complex nodular hyperplasia (n = 3), histiocytic sarcoma (n = 3), haemangiosarcoma (n = 1) and leiomyosarcoma (n = 1). Four samples were excluded from analysis due to extensive necrosis. An anti-podoplanin (PDPN) antibody was validated on canine tissue and used to assess expression of this protein as a potential indicator of the tissue of origin of the neoplasms (28/42 tumours were positive). There was a statistically significant difference in survival time between patients with stromal sarcoma (sarcoma from benign CNH and undifferentiated stromal sarcoma) and CNH (178 d versus 637 d, respectively; P = 0.027). Dogs with stromal sarcomas and high mitotic count (≥9 per 10 high-power fields) had a significantly shorter survival time (67 d versus 439 d; P = 0.01). Clinical diagnosis of splenic tumours should include evaluation for the presence of benign nodular hyperplasia morphology and immunohistochemistry to exclude more aggressive malignancies where adjuvant therapy is recommended. As in humans, PDPN may be an effective marker for stromal sarcomas of the canine spleen and immunopositivity suggests a fibroblastic reticular or follicular dendritic cell origin.

Development and validation of a multivariable model and online decision-support calculator to aid in preoperative discrimination of benign from malignant splenic masses in dogs

OBJECTIVE

To develop a multivariable model and online decision-support calculator to aid in preoperative discrimination of benign from malignant splenic masses in dogs.

ANIMALS

522 dogs that underwent splenectomy because of splenic masses.

PROCEDURES

A multivariable model was developed with preoperative clinical data obtained retrospectively from the records of 422 dogs that underwent splenectomy. Inclusion criteria were the availability of complete abdominal ultrasonographic examination images and splenic histologic slides or histology reports for review. Variables considered potentially predictive of splenic malignancy were analyzed. A receiver operating characteristic curve was created for the final multivariable model, and area under the curve was calculated. The model was externally validated with data from 100 dogs that underwent splenectomy subsequent to model development and was used to create an online calculator to estimate probability of splenic malignancy in individual dogs.

RESULTS

The final multivariable model contained 8 clinical variables used to estimate splenic malignancy probability: serum total protein concentration, presence (vs absence) of ≥ 2 nRBCs/100 WBCs, ultrasonographically assessed splenic mass diameter, number of liver nodules (0, 1, or ≥ 2), presence (vs absence) of multiple splenic masses or nodules, moderate to marked splenic mass inhomogeneity, moderate to marked abdominal effusion, and mesenteric, omental, or peritoneal nodules. Areas under the receiver operating characteristic curves for the development and validation populations were 0.80 and 0.78, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The online calculator (T-STAT.net or T-STAT.org) developed in this study can be used as an aid to estimate the probability of malignancy in dogs with splenic masses and has potential to facilitate owners' decisions regarding splenectomy.

Review of Histological Grading Systems in Veterinary Medicine

Tumor grading is a method to quantify the putative clinical aggressiveness of a neoplasm based on specific histological features. A good grading system should be simple, easy to use, reproducible, and accurately segregate tumors into those with low versus high risk. The aim of this review is to summarize the histological and, when available, cytological grading systems applied in veterinary pathology, providing information regarding their prognostic impact, reproducibility, usefulness, and shortcomings. Most of the grading schemes used in veterinary medicine are developed for common tumor entities. Grading systems exist for soft tissue sarcoma, osteosarcoma, multilobular tumor of bone, mast cell tumor, lymphoma, mammary carcinoma, pulmonary carcinoma, urothelial carcinoma, renal cell carcinoma, prostatic carcinoma, and central nervous system tumors. The prognostic relevance of many grading schemes has been demonstrated, but for some tumor types the usefulness of grading remains controversial. Furthermore, validation studies are available only for a minority of the grading systems. Contrasting data on the prognostic power of some grading systems, lack of detailed instructions in the materials and methods in some studies, and lack of data on reproducibility and validation studies are discussed for the relevant grading systems. Awareness of the limitations of grading is necessary for pathologists and oncologists to use these systems appropriately and to drive initiatives for their improvement.

Clinical relevance of splenic nodules or heterogeneous splenic parenchyma assessed by cytologic evaluation of fine-needle samples in 125 dogs (2011-2015)

Background

Splenic nodules and heterogeneous parenchyma are seen frequently in abdominal ultrasound examinations of dogs, but the clinical importance of these lesions remains unclear.

Objectives

To determine whether specific ultrasonographic findings correlate with clinically relevant cytologic diagnoses and determine what sonographic features are correlated with these diagnoses. Another objective was to develop a scoring rubric to help clinicians make decisions on whether or not certain ultasonographic findings of the spleen warrant evaluation by fine‐needle cytology.

Animals

One‐hundred twenty‐five adult client‐owned dogs with ultrasonographically identified splenic nodules, heterogeneous parenchyma, or both.

Methods

Medical records were retrospectively searched for ultrasound‐guided splenic fine‐needle cytology reports. Ultrasonographic images were assessed for nodule number, size, echogenicity and distal enhancement, degree of splenic heterogeneity, and peritoneal fluid. Dogs were divided into 2 groups: those with clinically important or clinically irrelevant cytologic findings. Potentially useful and discriminatory ultrasonographic findings were identified by statistical analysis, and the most useful findings were used to generate the scoring rubric.

Results

The clinically important group included 25 of 125 dogs (22 malignancies, 3 suppurative inflammation). Splenic nodules 1‐2 cm in diameter, peritoneal fluid, and >1 targetoid nodule were associated with clinically important cytologic findings. Receiver operator characteristic analysis showed that the scoring rubric was useful for identifying dogs in the clinically important group.

Conclusions and Clinical Importance

Splenic fine‐needle cytologic findings identified a clinically relevant diagnosis in 20% of dogs, and larger nodule size, number of targetoid lesions, and presence of peritoneal fluid increase the likelihood of detection of clinically important disease.

Canine Splenic Nodular Lymphoid Lesions: Immunophenotyping, Proliferative Activity, and Clonality Assessment

Canine splenic lymphoid nodules are currently classified as indolent lymphomas (marginal zone lymphoma [MZL], mantle cell lymphoma [MCL]) or nodular hyperplasia (lymphoid [LNH] or complex [CNH] type). Their differentiation can be difficult on morphology, because of similar histologic appearance and poorly defined diagnostic criteria. Thirty-five surgical samples of splenic lymphoid nodules were reviewed in order to assess the diagnostic contribution of immunophenotyping, proliferative activity and clonality (PARR) in differentiating between hyperplastic and neoplastic lesions. Proliferative activity was evaluated by double immunolabeling for Ki-67 and CD79a, in order to separately assess the proliferative activity of B cells and non-B cells. Definitive diagnoses were MZL ( n = 11), MCL ( n = 4), LNH ( n = 10), and CNH ( n = 10). The overall concordance between histology and PARR was above 90%. Lymphomas had a significantly higher percentage of CD79a-positive areas (mean, 36.30%; P = .0004) and a higher B-cell proliferative activity (median Ki-67 index, 5.49%; P = .0012). The threshold value most accurately predicting a diagnosis of lymphoma was ≥28% of B-cell areas, with a Ki-67 index above 3%. Dogs were monitored for a median follow-up time of 870 days (IQR, 569-1225), and no relapses were documented. Overall median survival time was 1282 days. The combination of histology, immunohistochemistry and PARR can improve the diagnostic accuracy for canine splenic lymphoid nodules, although the long-term behavior of these lesions appears similar.

Triple-phase helical computed tomography in dogs with solid splenic masses

We investigated the utility of triple-phase helical computed tomography (CT) in differentiating between benign and malignant splenic masses in dogs. Forty-two dogs with primary splenic masses underwent triple-phase helical CT scanning (before administration of contrast, and in the arterial phase, portal venous phase, and delayed phase) prior to splenectomy. Tissue specimens were sent for pathological diagnosis; these included hematomas (n=14), nodular hyperplasias (n=12), hemangiosarcomas (n=11), and undifferentiated sarcomas (n=5). The CT findings were compared with the histological findings. Nodular hyperplasia significantly displayed a homogeneous normal enhancement pattern in all phases. Hemangiosarcoma displayed 2 significant contrast-enhancement patterns, including a homogeneous pattern of poor enhancement in all phases, and a heterogeneous remarkable enhancement pattern in the arterial and portal venous phases. Hematoma and undifferentiated sarcoma displayed a heterogeneous normal enhancement pattern in all phases. The contrast-enhanced volumetric ratios of hematoma tended to be greater than those of undifferentiated sarcoma. Our study demonstrated that the characteristic findings on triple-phase helical CT could be useful for the preoperative differentiation of hematoma, nodular hyperplasia, hemangiosarcoma, and undifferentiated sarcoma in dogs. Triple-phase helical CT may be a useful diagnostic tool in dogs with splenic masses.

Canine Indolent Nodular Lymphoma

Sixty-six cases of indolent canine lymphoid proliferation were reviewed. Age ranged from 1.5 to 16 years (median 9.0 years). Dogs of 26 breeds, plus 13 of mixed breeding or unknown lineage, were represented. B-Cell lymphomas (CD79a+) predominated. Marginal zone lymphoma (MZL), the largest group, involved lymph node (33 cases) and spleen (13 cases), with both tissues involved in five of these cases. Follicular lymphoma (FL) involved lymph nodes (five cases), and mantle cell lymphoma (MCL) occurred as solitary splenic masses (three cases). Nodal CD3+ T-zone lymphomas (TZL) (10 cases), were included since they resembled late-stage MZL at the architectural level. Two cases of marginal zone hyperplasia (MZH) were included to aid in differentiation of early MZL. Clonality status was determined in 54 cases by analysis of immunoglobulin heavy chain (IGH) and T-cell antigen receptor gamma (TCRG) gene rearrangement. Clonal rearrangement of IGH was detected in 28 of 35 MZL cases (80%), four of four FL cases (100%) and three of three MCL cases (100%). Concurrent cross lineage rearrangement of TCRG was detected in six MZL and two FL cases. Clonal rearrangement of TCRG was documented in five of eight TZL cases (63%). Limited survival data obtained for 18 dogs indicated that the B-cell lymphomas (MZL, MCL, and FL) and the T-cell lymphoma (TZL) were associated with indolent behavior and long survival. Although to the authors' knowledge, the true incidence of canine indolent lymphomas is unknown, the tumors are not rare and may have been underrecognized. Recognition of their architectural features, routine application of immunophenotyping, and molecular clonality assessment should alleviate this.

A review of histiocytic diseases of dogs and cats

Histiocytic proliferative disorders are commonly observed in dogs and less often cats. Histiocytic disorders occur in most of the dendritic cell (DC) lineages. Canine cutaneous histiocytoma originates from Langerhans cells (LCs) indicated by expression of CD1a, CD11c/CD18, and E-cadherin. When histiocytomas occur as multiple lesions in skin with optional metastasis to lymph nodes and internal organs, the disease resembles cutaneous Langerhans cell histiocytosis of humans. Langerhans cell disorders do not occur in feline skin. Feline pulmonary LCH has been recognized as a cause of respiratory failure due to diffuse pulmonary infiltration by histiocytes, which express CD18 and E-cadherin and contain Birbeck's granules. In dogs and cats, histiocytic sarcomas (HS) arise from interstitial DCs that occur in most tissues of the body. Histiocytic sarcomas begin as localized lesions, which rapidly disseminate to many organs. Primary sites include spleen, lung, skin, brain (meninges), lymph node, bone marrow, and synovial tissues of limbs. An indolent form of localized HS, progressive histiocytosis, originates in the skin of cats. Hemophagocytic HS originates in splenic red pulp and bone marrow macrophages in dogs and cats. In dogs, histiocytes in hemophagocytic HS express CD11d/CD18, which is a leuko-integrin highly expressed by macrophages in splenic red pulp and bone marrow. Canine reactive histiocytic diseases, systemic histiocytosis (SH) and cutaneous histiocytosis, are complex inflammatory diseases with underlying immune dysregulation. The lesions are dominated by activated interstitial DCs and lymphocytes, which invade vessel walls and extend as vasocentric infiltrates in skin, lymph nodes, and internal organs (SH).

Demonstration of the Cell Clonality in Canine Hematopoietic Tumors by X-chromosome Inactivation Pattern Analysis

X-chromosome inactivation pattern (XCIP) analysis has been widely used to assess cell clonality in various types of human neoplasms. In this study, a polymerase chain reaction–based canine XCIP analysis of the androgen receptor ( AR) gene was applied for the assessment of cell clonality in canine hematopoietic tumors. This XCIP analysis is based on the polymorphic CAG repeats in the AR gene and the difference of methylation status between active and inactive X chromosomes. We first examined the polymorphisms of 2 CAG tandem repeats in the AR gene in 52 male and 150 female dogs of various breeds. The 2 polymorphic CAG repeats contained 9 to 12 and 10 to 14 CAGs in the first and second CAG repeats, respectively. Of the 150 female dogs, 74 (49.3%) were heterozygous for the first and/or second polymorphic CAG tandem repeats, indicating the utility of XCIP analysis in these dogs. Canine XCIP analysis was then applied to clinical samples from female dogs with canine high-grade lymphoma, chronic myelogenous leukemia, acute myelogenous leukemia, and benign lymph node hyperplasia. Of 10 lymphoma cell samples, 9 (90%) showed skewed XCIPs, indicating their clonal origins, whereas all the nonneoplastic lymph node samples showed balanced XCIPs. Moreover, bone marrow specimen from a dog with acute myelogenous leukemia and peripheral leukocyte specimens from 2 dogs with chronic myelogenous leukemia showed skewed XCIPs. XCIP analysis was successfully employed to demonstrate the cell clonality of canine hematopoietic tumors in this study and will be applicable to evaluate the clonality in various proliferative disorders in dogs.

Inflammatory myofibroblastic tumour in the nasal cavity of a dog

A 4·5-year-old, female neutered Leonberger was presented with a 2-month history of sneezing, nasal discharge and epistaxis. A presumptive diagnosis of nasal aspergillosis was made based on a suspected (fungal) granuloma on rhinoscopic examination and fungal hyphae on cytological examination. A poor response to targeted therapy was observed and computed tomography 16 months after initial presentation revealed a progressive, locally invasive mass lesion. Histopathological and immunohistochemical analysis of deep surgical biopsies revealed a spindle cell population and a plasma cell rich inflammatory infiltrate, with diffuse expression of vimentin, supporting a diagnosis of inflammatory myofibroblastic tumour. Complete resolution of the nasal discharge and reduced sneezing frequency was reported 9 months post-surgical debridement via rhinotomy. To the authors' knowledge, this is the first report of IMT in the nasal cavity of a dog. IMT should be considered when presented with a nasal mass lesion, particularly if histopathological features and clinical course are inconsistent.

Evaluation of splenectomy as a risk factor for gastric dilatation-volvulus

OBJECTIVE

To evaluate whether dogs undergoing splenectomy had an increased risk of gastric dilatation-volvulus (GDV), compared with a control group of dogs undergoing enterotomy.

DESIGN

Retrospective case-control study.

ANIMALS

219 dogs that underwent splenectomy for reasons other than splenic torsion (splenectomy group; n = 172) or enterotomy (control group; 47) without concurrent gastropexy.

PROCEDURES

Medical records were reviewed for information on signalment, date of surgery, durations of surgery and anesthesia, reason for splenectomy, histopathologic findings (if applicable), whether gastropexy was performed, duration of follow-up, and date of death (if applicable). Follow-up information, including occurrence of GDV, was obtained via medical records review and a written client questionnaire.

RESULTS

Reasons for splenectomy included splenic neoplasia, nonneoplastic masses, infarction, traumatic injury, and adhesions to a gossypiboma. Incidence of GDV following surgery was not significantly different between dogs of the splenectomy (14/172 [8.1 %]) and control (3/47 [6.4%]) groups. Median time to GDV for the 17 affected dogs was 352 days (range, 12 to 2,368 days) after surgery. Among dogs that underwent splenectomy, sexually intact males had a significantly higher incidence of GDV (4/16) than did castrated males and sexually intact or spayed females (10/156). Incidence of GDV among sexually intact male dogs did not differ between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Results did not support a recommendation for routine use of prophylactic gastropexy in dogs at the time of splenectomy. Other patient-specific risk factors should be assessed prior to recommending this procedure.

Histologic and immunohistochemical review of splenic fibrohistiocytic nodules in dogs

BACKGROUND

Splenic fibrohistiocytic nodules (SFHN) are commonly diagnosed. It is suspected that these represent a heterogeneous group of malignant and nonmalignant diseases, separation of which could improve the ability of clinicians to prognosticate for dogs.

HYPOTHESIS/OBJECTIVES

Immunohistochemistry will differentiate histologic diagnoses within the group of SFHN; survival after splenectomy is associated with those histologic types.

ANIMALS

Thirty-two dogs with SFHN treated by or under direction from veterinary oncologists.

METHODS

Retrospective case record analysis from dogs followed from splenectomy until death. Clinical, histopathologic, and immunohistochemistry data analyzed for an association with survival time.

RESULTS

Thirty-two dogs had SFHN; grade 1 (2 dogs), grade 2 (9 dogs), and grade 3 (lymphoid percentage <40%; 21 dogs). Twenty-two dogs died, 10 were censored (9 alive median of 883 days after splenectomy). Median overall survival was 387 days, and grade 3 SFHN was negatively [corrected] associated with survival time as previously reported (P < .001). Of 31 available samples, dogs had diseases reclassified as nodular hyperplasia (13; 8 complex, 5 lymphoid including 2 marginal zone), lymphoma (4; 2 marginal zone lymphoma, 1 high grade B-cell lymphoma, and 1 marginal zone transitional to high grade B-cell lymphoma), 8 stromal sarcomas, and 6 histiocytic sarcomas. Dogs with histiocytic sarcoma had worse survival (median 74 days) than dogs with other diseases.

CONCLUSIONS AND CLINICAL IMPORTANCE

Splenic histiocytic sarcoma is an aggressive disease; however, some dogs with stromal sarcomas had long survival times. The term SFHN is no longer warranted for this group of disorders.

Molecular prevalence of Bartonella, Babesia, and hemotropic Mycoplasma sp. in dogs with splenic disease

BACKGROUND

Among diseases that cause splenomegaly in dogs, lymphoid nodular hyperplasia (LNH), splenic hemangiosarcoma (HSA), and fibrohistiocytic nodules (FHN) are common diagnoses. The spleen plays an important role in the immunologic control or elimination of vector-transmitted, blood-borne pathogens, including Bartonella sp., Babesia sp., and hemotropic Mycoplasma sp.

OBJECTIVE

To compare the prevalence of Bartonella sp., Babesia sp., and hemotropic Mycoplasma sp. DNA in spleens from dogs with LNH, HSA, and FHN.

MATERIALS AND METHODS

Paraffin-embedded, surgically obtained biopsy tissues from LNH (N = 50), HSA (N = 50), and FHN (N = 37) were collected from the anatomic pathology archives. Spleens from specific pathogen-free (SPF) dogs (N = 8) were used as controls. Bartonella sp., Babesia sp., and Mycoplasma sp. DNA was amplified by PCR, followed by DNA sequencing.

RESULTS

Bartonella sp. DNA was more prevalent in FHN (29.7%) and HSA (26%) as compared to LNH (10%) (P = .019, .0373, respectively) or control spleens (0.0%). The prevalence of Babesia sp. and hemotropic Mycoplasma sp. DNA was significantly lower than Bartonella sp. DNA in HSA (P = .0005, .006, respectively) and FHN (P = .003, .0004, respectively). There was no statistically significant difference in DNA prevalence among the 3 genera in the LNH group.

CONCLUSIONS

The higher prevalence of Bartonella sp. in FHN and HSA warrants future investigations to determine if this bacterium plays a role in the development of these splenic diseases.

Histiocytic sarcomas in flat-coated retrievers: a summary of 37 cases (November 1998-March 2005)

Thirty-seven cases of histiocytic-like sarcomas (HLSs) in flat-coated retriever dogs were evaluated retrospectively. This tumour accounted for 36% of the malignant tumours seen in this breed during the study period. The median age at presentation was 8.2 years. Thirty-four dogs presented with a swelling or mass in a muscle group or surrounding a joint. The remaining three presented for rib (1), cutaneous (1) or primary splenic origin (1). A high rate of metastasis to local lymph nodes (45%), thorax (20%) and abdominal organs (20% confirmed) was seen. Overall metastastic rate by the time of death was 70%. The median survival for all dogs was 123 days. The most significant prognostic indicator was presence of distant metastasis at the time of diagnosis with median survival of 68 or 200 days, with or without metastasis, respectively. Chemotherapy and radiation therapy significantly improved survival. Dogs given chemotherapy survived a median of 185 versus 34 days for dogs that were not (P = 0.0008). Dogs treated with radiation survived a median of 182 versus 60 days for those that were not (P = 0.0282). Dogs receiving only palliative therapy survived a median of 17 versus 167 days in dogs receiving any kind of radiation, chemotherapy, surgery or combinations. A set protocol of radiation and CCNU (RTCCNU) induced minimal toxicity and provided a median survival of 208 versus 68 days for all other dogs. While this tumour carries a poor long-term prognosis in flat-coated retrievers, it is reasonable to treat these dogs for palliation of signs and extension of life.

Prevalence of hemangiosarcoma in anemic dogs with a splenic mass and hemoperitoneum requiring a transfusion: 71 cases (2003-2005)

OBJECTIVE

To determine prevalence of splenic hemangiosarcoma in anemic dogs with a splenic mass and hemoperitoneum requiring a transfusion and to identify factors that could differentiate between dogs with hemangiosarcoma and dogs with other splenic masses at the time of hospital admission.

DESIGN

Retrospective case series.

ANIMALS

71 dogs.

PROCEDURES

Medical records, blood bank logs, and histologic reports of dogs with a splenic mass and hemoperitoneum that required a transfusion between 2003 and 2005 were reviewed. Dogs that received a transfusion of packed RBCs, were splenectomized, and had a definitive histologic diagnosis were included.

RESULTS

Signalment of dogs was similar to that in other reports. Malignant splenic neoplasia was identified in 54 of 71 (76.1%) dogs, whereas 17 of 71 (23.9%) dogs had a benign splenic lesion. Of 54 dogs with malignant splenic neoplasia, 50 (92.6% [70.4% of all dogs]) had splenic hemangiosarcoma. In addition, dogs with splenic hemangiosarcoma had significantly lower total solids (TS) concentrations and platelet counts at admission. Finally, hemoperitoneum was strongly associated with a diagnosis of splenic hemangiosarcoma.

CONCLUSIONS AND CLINICAL RELEVANCE

In this clinical population of dogs, prevalence of hemangiosarcoma was higher than in other studies. Dogs with hemangiosarcoma in this study had significantly lower TS concentrations and platelet counts at the time of admission, compared with values for dogs with other splenic masses. No other markers were useful in differentiating dogs with hemangiosarcoma. It is important to discuss the prevalence of and poor prognosis associated with hemangiosarcoma with owners when they are contemplating whether to proceed with treatment.

Nódulos fibro-histiocíticos no baço de uma cadela: relato de caso

Descreve-se a ocorrência de múltiplos nódulos fibro-histiocíticos no baço de uma cadela Rottweiler, de sete anos. O diagnóstico foi feito por histopatologia e confirmado por imunoistoquímica positiva para ED1, CD18, vimentina e lisozima. O animal foi sacrificado três meses após o diagnóstico, por severo agravamento dos sinais clínicos.

Diagnostic pathology for the cancer patient

It is necessary to have a cooperative relationship between the clinician and the pathologist, because information from both is critical for determining the best case management and favorable prognosis. The principle roles of the veterinary pathologist are to describe the submitted tissues, to determine the nature of the tumor, and to assess completeness of surgical margins. Recently, the Council of the American College of Veterinary Pathologists (ACVP) appointed an ad hoc committee on oncology to evaluate oncologists' needs by polling members of the Veterinary Cancer Society (VCS). The committee's vision was to review morphologic, immunologic, and molecular techniques so that veterinary pathologists could meet the current and future diagnostic and prognostic needs of oncologic veterinarians. The factors determined to be most important to the VCS members in selecting a diagnostic pathology provider included, in order of importance: (1) reliability of results; (2) short turnaround-time; (3) easy access for consultation; (4) rapport with pathologist; (5) convenience of service; and (6) cost of service. This manuscript will attempt to review improved morphologic, immunologic, and molecular techniques to provide for the future diagnostic and prognostic needs of oncologic veterinarians.

Immunohistochemical and histopathologic features of 14 malignant fibrous histiocytomas from Flat-Coated Retrievers

Flat-Coated Retrievers seem to be at increased risk of developing soft-tissue sarcomas, and undifferentiated round cell or spindle cell sarcomas account for approximately 59% of sarcomas in the breed. In an attempt to classify these tumors further, formalin-fixed, paraffin-embedded sections from 14 undifferentiated sarcomas from Flat-Coated Retrievers were reviewed and examined with a panel of histologic and immunohistochemical stains. The panel included vimentin, desmin, Myo D1, smooth muscle actin, cytokeratin, S100, von Willebrand factor (factor VIII), Mac 387, CD3, major histocompatibility complex (MHC) class II, and CD79a. The majority of the sarcomas showed greater than 70% staining for MHC class II. We conclude that these undifferentiated sarcomas in Flat-Coated Retrievers belong to a spectrum of tumors with varying proportions of characteristic cell types and morphologic features, some of which fit the diagnostic criteria for malignant fibrous histiocytoma. Many of these sarcomas seem to have a significant myofibroblast component and a mild or moderate T cell infiltrate but the precise cell lineage is still uncertain.

Localized and disseminated histiocytic sarcoma of dendritic cell origin in dogs

Canine histiocytic proliferative disorders include a wide spectrum of diseases characterized by different biologic behaviors. The etiology and pathogenesis of these diseases are largely unknown. The clinicopathologic, morphologic and immunophenotypic characteristics of canine localized and disseminated histiocytic sarcoma were examined in 39 dogs. Rottweilers, Bernese Mountain Dogs, and retrievers were most commonly affected (79%). Localized histiocytic sarcomas (19 dogs) arose from a single site, and metastatic lesions were observed in draining lymph nodes. Predilection sites were subcutis and underlying tissues on extremities, but tumors occurred in other locations, including spleen, lung, brain, nasal cavity, and bone marrow. Disseminated histiocytic sarcomas (20 dogs), a multisystem disease previously described as malignant histiocytosis, primarily affected spleen, lungs, bone marrow, liver, and lymph nodes. Both localized and disseminated canine histiocytic sarcomas were composed of pleomorphic tumor cell populations. CD1+, CD4-, CD11c+, CD11d-, MHC II+, ICAM-1 +, Thy-1 +/- tumor cells were identified in all snap-frozen samples (31 dogs). This phenotype is characteristic for myeloid dendritic antigen-presenting cell lineage. Hence, canine localized and disseminated histiocytic sarcomas are likely myeloid dendritic cell sarcomas. Dendritic antigen-presenting cells are a heterogeneous cell population with regards to their ontogeny, phenotype, function, and localization. The exact sublineage of the proliferating dendritic antigen-presenting cells involved in canine histiocytic sarcomas remains to be determined. Phenotypic analysis of formalin-fixed tissues from eight dogs was limited by available markers. Morphologic features and the phenotype CD18+, CD3-, and CD79a- were the most useful criteria to indicate likely histiocytic origin.

Immunolocalization of the calcium binding S100A1, S100A5 and S100A6 proteins in the dog cochlea during postnatal development

The immunolocalization of three members of the S100 calcium-binding protein family was investigated in the dog cochlea during normal postnatal development. Sections of decalcified and paraffin-embedded cochleae from 16 beagle puppies aged from birth to 3 months were treated with polyclonal antisera raised against the human recombinant S100A1, S100A5, and S100A6 proteins. At birth, in the dog cochlea, S100A1 was expressed in the immature Deiter's cells, and slightly in the pillar cells. From the second week, S100A1 was detected in the supporting structures of the organ of Corti, i.e. the Deiter's, the pillar, the border, and the Hensen's cells, and in the reticular membrane. From birth onwards, S100A5 remained a neuronal-specific protein, only located in a subpopulation of neurons in the spiral ganglion. S100A6 was not expressed at birth. From the second week of life, the Schwann cells and nerve sheaths in the modiolus, in the spiral ganglion, and running in the direction of the organ of Corti exhibited S100A6-labeling. From the 12th postnatal day, some scattered intermediate cells started to express S100A6 protein in the stria vascularis. The number of labeled intermediate cells increased during the third week. At adult stage, the intermediate cells were S100A6-stained with cytoplasmic labeling throughout the stria vascularis from the base to the apex of the cochlea. None of the other cochlear structures expressed the S100 proteins under study during the postnatal development of the dog cochlea. The S100A1, S100A5, S100A6 immunostaining was limited to specific cell types in dog cochlea. These S100 proteins were useful markers in the study of supporting cells, neurons, nerve fibers sheaths and stria vascularis (S100A6) during the normal postnatal development of the dog cochlea.

Splenic myeloid metaplasia, histiocytosis, and hypersplenism in the dog (65 cases)

Splenectomy specimens from 65 dogs with severe, diffuse, sustained, and progressive splenomegaly were examined. The clinical signs, hematology, and serum chemistry values in for the dogs were not useful diagnostic features. Microscopic changes in the spleens were distinctive and consisted of 1) myeloid metaplasia, 2) histiocytosis, 3) erythrophagocytosis, and 4) thrombosis with segmental infarction. Ultrastructural features suggested proliferative changes in the splenic reticular cells and macrophages (reticular meshwork) that described a continuum from reactive changes associated with immunologic damage of erythrocytes to neoplastic proliferation of histiocytic components. Thirty percent of the dogs survived 12 months. Approximately one half (53%) of the dogs with complete postmortem evaluations showed multiorgan involvement with a tissue distribution and cell morphology consistent with histiocytic neoplasia. For the remaining dogs (47%), only splenic pathology was consistently present, and a specific cause of death was often not evident. Distinctive histologic changes in the splenic tissues-including mitotic activity, erythrophagocytosis, giant cell formation, thrombosis/ infarction, and the proportion and distribution of histiocytic and hematopoietic cells-were statistically evaluated for prognostic relevance. The presence of giant cells was the only reliable prognostic feature, and that was indicative of a fatal outcome. These descriptive changes of myeloid metaplasia in the canine spleen are compared with the human clinical and pathologic syndromes of 1) agnogenic myeloid metaplasia, 2) hemophagocytic syndromes, and 3) hypersplenism. These diseases in humans produce histopathologic changes in the spleen that are similar to those observed in the canine splenic tissue we examined in this study.