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S. Ettinger1
FELINE LYMPHOMA: Latest Information Sue Ettinger, DVM, DACVIM (Oncology)
Dr Sue Cancer Vet PLLC and Animal Specialty & Emergency Center Wappinger Falls, NY, USA
Lymphoma (LSA) is one of the most commonly occurring cancers in cats. Lymphoma is collection of cancers arising from the malignant transformation of lymphocytes and is a diverse group of neoplasms with the common origin of the lymphorecticular cells. In contrast to
dogs, feline lymphoma most commonly affects the gastrointestinal (GI) tract. Like dogs, lymphoma is a systemic disease that requires chemotherapy in almost all cases. Outcomes for treated cats are however
less predictable than dogs, but cats tend to tolerate chemotherapy better than dogs. Treated cats do live longer, and chemotherapy is generally well-tolerated. The diagnostic and treatment choices can be confusing and overwhelming, especially when distinguishing IBD, low grade lymphoma, and high grade lymphoma.
Feline Chronic Small Bowel Disease (CSBD)
CSBD includes inflammatory bowel disease (IBD) and enteropathy-associated T-cell LSA (EATL) type 2 (low grade lymphoma). EATL type 2 is the most common infiltrative GI LSA in cats, and treatment is different than IBD. In 2013 Norsworthy et al reported that CSBD often is often considered normal by cat owners. Excuses by owners include: “He just eats fast”, “She is a nervous cat”, “He has a sensitive stomach”, “She gets hairballs”, “He’s always done this.”
In this study, the authors looked at the association of clinical signs and disease in 100 cats that had an AUS of small bowel >0.28 cm in > 2 locations. These cats had >1: vomiting >2x /month for at least 3 months, several weeks of small bowel diarrhea, and weight loss > 0.5 kg in last 6 months. Interestingly, 26 cats were getting wellness exam. 65 cats did not have surgery and were excluded. Clinical signs included weight loss 70%, vomiting >2x 61%, diarrhea 11%, and V/D 13%. 92% had at least 1 AUS measurement >0.3 cm, 8 cats 0.29- 0.29 cm, and 76 cats 1 measurement <0.28 cm. 99 of 100 had cats had IBD or LSA. Only 1 cat had normal histology. 49% had IBD/chronic enteritis. 46% had LSA
(n=44 EATL type2).Cats <8 years old had enteritis, and cats > 8 years old enteritis or cancer. The 1 normal cat was 5 years old.
Cats with GI clinical signs are common and should undergo diagnostics. Do not let clients make excuses, and get a good history. Chronic vomiting is often considered normal, but vomiting is not normal! Clinical signs should trigger abdominal ultrasound. One of the common excuses is vomiting hairballs is normal. Is vomiting hairballs is normal? Does chronic small bowel disease slow bowel movement and predispose to formation?
Pathology and Behavior
For alimentary/GI LSA, the LSA typically involved the intestines alone or intestines, lymph nodes (LN), and liver. In the GI tract, it can be solitary vs diffuse. 55% of GI tumors are LSA. Siamese are at increased risk. The GI form typically occurs in aged cats of 12 to 13 years old. The small intestines are four times more affected than the large intestines.
Enteropathy-associated T-cell LSA (EATL) has 2 forms. EATL Type I is intermediate to large B-cells, high grade, lymphoblastic lymphoma. This form often has a palpable mass. EATL Type II is called small cell, low grade, lymphocytic lymphoma. This form is more diffuse throughout the GIT and T-cell is more common.
Clinical Appearance:
For low grade small cell LSA, clinical signs include weight loss (83-100%), V/D (73-88%), anorexia (66%), and icterus (7%). 70% have abnormal palpation on exam, either thickened GI or a palpable mass 33%. The history is usually chronic over several months, with a median 6 months.
For high grade LSA, the clinical signs are similar but icterus is more common and the onset is more rapid – days to weeks. A palpable mass is common. Rarely the cat will present with acute abdomen due to obstruction or perforation.
Diagnosis and Staging
Basic diagnostics include CBC, chemistry panel, and UA. For the GI forms, 23% have panhypoproteinemia and 76% are anemic. Test for FeLV/FIV status. Diagnosis typically made with cytology or histology of a LN or organ. Cytology may be inconclusive and be reported
as benign hyperplastic and reactive, and histology will be needed. Other diagnostics may include abdominal ultrasound (AUS) and chest radiographs. Bone marrow cytology may be recommended especially for cases with anemia, leukopenia, or cellular atypia. Phenotype can be determined with PARR 80% sensitive or flow cytometry.
An Urban Experience

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