Distinguishing Intestinal Lymphoma From Inflammatory Bowel Disease in Canine Duodenal Endoscopic Biopsy Samples

Abstract

Inflammatory bowel disease (IBD) and intestinal lymphoma are intestinal disorders in dogs, both causing similar chronic digestive signs, although with a different prognosis and different treatment requirements. Differentiation between these 2 conditions is based on histopathologic evaluation of intestinal biopsies. However, an accurate diagnosis is often difficult based on histology alone, especially when only endoscopic biopsies are available to differentiate IBD from enteropathy-associated T-cell lymphoma (EATL) type 2, a small cell lymphoma. The purpose of this study was to evaluate the utility of histopathology; immunohistochemistry (IHC) for CD3, CD20, and Ki-67; and polymerase chain reaction (PCR) for antigen receptor rearrangement (T-cell clonality) in the differential diagnosis of severe IBD vs intestinal lymphoma. Endoscopic biopsies from 32 dogs with severe IBD or intestinal lymphoma were evaluated. The original diagnosis was based on microscopic examination of hematoxylin and eosin (HE)-stained sections alone followed by a second evaluation using morphology in association with IHC for CD3 and CD20 and a third evaluation using PCR for clonality. Our results show that, in contrast to feline intestinal lymphomas, 6 of 8 canine small intestinal lymphomas were EATL type 1 (large cell) lymphomas. EATL type 2 was uncommon. Regardless, in dogs, intraepithelial lymphocytes were not an important diagnostic feature to differentiate IBD from EATL as confirmed by PCR. EATL type 1 had a significantly higher Ki-67 index than did EATL type 2 or IBD cases. Based on the results of this study, a stepwise diagnostic approach using histology as the first step, followed by immunophenotyping and determining the Ki67 index and finally PCR for clonality, improves the accuracy of distinguishing intestinal lymphoma from IBD in dogs.

Changes in Foxp3-Positive Regulatory T Cell Number in the Intestine of Dogs With Idiopathic Inflammatory Bowel Disease and Intestinal Lymphoma

“…9,30 In this study, 48, 46, and 30 dogs had IBD, small cell lymphoma, and large cell lymphoma, respectively. The clinical severity was significantly higher and the overall survival, significantly shorter, in the order of large cell lymphoma, small cell lymphoma, and IBD.…”

Gastrointestinal B-lymphoblastic lymphoma in a dog: a case report

“…It can be difficult to differentiate lymphoma from LPE based on morphology alone, and special tests that enhance the accuracy of histopathology are needed (Evans et al 2006;Carrasco et al 2015).…”

“…Carrasco et al (2015) reported a 100% prevalence of T-cell alimentary lymphomas, but the samples were taken from duodenum only. No patient affected by gastric or colorectal lymphoma was included in the study.…”

“…Flow cytometry and immunohistochemistry verified the B-cell phenotype of the malignancy. To distinguish alimentary lymphoma from inflammatory bowel disease, Carrasco et al (2015) recommend combining histopathology, immunophenotyping, determination of the Ki-67 index and clonality testing.…”

Expression of Ki-67, PCNA markers and the apoptotic index in the inflammatory bowel disease in dogs and its diagnostic values

“…U psów z nieswoistym zapaleniem jelit jeszcze nie przeprowadzono badań nad przydatnością oznaczania parametrów proliferacji w zależności od natężenia procesu zapalnego. Parametry proliferacji są wykorzystywane do różnicowania chłoniaka jelit od NZJ u psów (3).…”