Cytology of endoscopically obtained biopsies for the diagnosis of chronic intestinal diseases in cats

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.

Correlation between the FCEAI and diagnostic parameters in chronic enteropathies in 147 cats (2006-2012)

OBJECTIVE

The Feline Chronic Enteropathy Activity Index (FCEAI) has been established as a quantitative index for disease activity in chronic enteropathies in cats. A definite diagnosis is aimed at histology with initial exclusion of extraintestinal causes by laboratory examinations, diagnostic imaging and endoscopy. The study aimed to examine diagnostic parameters and FCEAI in chronic gastroenteropathies.

MATERIALS AND METHODS

A retrospective case review of 147 cats with chronic enteropathies was performed. In all patients, the FCEAI was established and endoscopy performed including biopsies and duodenal cytology. Histopathologic reports were reviewed for the diagnosis of lymphoma and architectural changes (epithelial integrity, villi/gland atrophy, intestinal crypt atrophy, lymphangiectasia, epitheliotropism/infiltration of intraepithelial lymphocytes). A cytopathologic score (CS) and histopathologic score (HS) regarding lymphocytic intestinal infiltration were assigned. Statistical dependency analysis was used to determine correlations between the FCEAI, lymphoma, architectural changes, CS, HS, serum concentrations of cobalamin, folate and albumin.

RESULTS

The 147 cats consisted of predominately European Shorthair cats (n = 126), were mostly castrated (n = 127) and had a mean age of 9.8 (1-17) years. For the proven lymphoma group (12.2%; n = 18) and the non-lymphoma group a mean FCEAI of 7.3 (4-17) and 6.6 (2-13), respectively, was established. The FCEAI showed a low correlation with the CS (p = 0.010; R = 0.22) and intestinal villous atrophy (n = 121; p = 0.035; R = 0.19). Cats with a CS of 0 had a significant lower FCEAI score (p = 0.015) than cats with all other CSs. The histo- and cytopathologic scores were highly related (p < 0.001; R = 0.43). The gastric intraepithelial lymphocytic infiltration (n = 131) was significantly correlated to serum folate (p = 0.014; R = -0.56) and albumin (p = 0,048; R = -0.20).

CONCLUSION

The FCEAI showed only a few correlations. Not only the grade of inflammation, but also the histologic architectural changes are of importance.

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.

Diagnostic contribution of cytological specimens obtained from biopsies during gastrointestinal endoscopy in dogs and cats

OBJECTIVES

The aims of this study were to compare cytological samples obtained from endoscopic biopsies using "imprint" and "squash" techniques, and to evaluate the potential value of cytology compared to histology in reaching the diagnosis.

MATERIALS AND METHODS

Eighteen dogs and five cats undergoing endoscopy for chronic gastrointestinal signs were prospectively included. Imprint and squash samples were obtained from one biopsy and then analysed. Comparison between cytology and histology was performed using Cohen's j coefficient.

RESULTS

Appropriate samples for cytological evaluation were more often obtained with the squash technique (96% of the cases versus 68% with the imprint technique). The diagnoses obtained with cytological samples and by histology, considered as the gold standard, were compared. The same diagnosis was obtained with the squash technique in 65% of the cases. Furthermore, cytology was considered complementary to histology for gastric spiral organisms and mast cells identification.

CLINICAL SIGNIFICANCE

These results suggest that squash cytology obtained from endoscopic biopsies of the gastrointestinal tract can provide relevant and additional information to histology in dogs and cats.