Differentiation of Feline IBD from Intestinal Lymphoma: Does It Really Matter?

The inflammatory bowel diseases (IBD) are the most common causes of chronic vomiting and diarrhea in dogs and cats, and refer to a group of poorly understood enteropathies characterized by the infiltration of the gastrointestinal mucosa by inflammatory cells. The cellular infiltrate is composed of variable populations of lymphocytes, plasma cells, eosinophils, macrophages, neutrophils, or combinations of these cells. Changes in the mucosal architecture characterized by villous atrophy, fusion, fibrosis, and lacteal dilation frequently accompany the cellular infiltrates.

Gastrointestinal lymphoma is the most commonly encountered form of lymphoma in cats, and is characterized by lymphoid infiltration of the stomach and/or intestines with or without mesenteric lymph node involvement. More recent articles have reported that up to 72% of the newly diagnosed feline lymphoma cases are alimentary in origin. Cats with GIT lymphoma have a median age of 12 years and they are generally FeLV negative. With regard to tumor location, most cases of GIT lymphoma involve the small intestine (particularly the jejunum), with a smaller percentage (approximately 18%) involving the stomach only. Approximately 80% of GIT lymphomas involve the small intestine only, and approximately 8% involve the large intestine only. There are 3 main histological types of gastrointestinal lymphoma in cats: diffuse small cell T-cell lymphoma, considered as a low grade lymphoma; large cell B-cell lymphoma, a high grade lymphoma which is considered more aggressive and usually involves the mesenteric lymph nodes; and large granular cell lymphoma which is the least common form of gastrointestinal lymphoma and also carries a poorer prognosis. The concurrent diagnosis of lymphoplasmacytic IBD with small cell intestinal lymphoma has been well documented in cats, and the two disorders commonly occur together. It has been postulated by multiple authors that the chronic inflammatory process precedes and acts as a trigger for the subsequent onset of gastrointestinal lymphoma. This was also reported by Moore et al, where 60% of the cats with lymphoma had prior clinical signs indicative of IBD.  […]