An 8-year-old male female, domestic longhair cat presented to the veterinary specialist centre with weight loss, anorexia and palpable abdominal mass. Physical examination revealed mesenteric lymphadenomegaly, mediastinal lymphadenomegaly and pleural effusion. Ultrasound guided FNA of the thickened intestinal wall and affected lymph nodes was performed. Cytology showed increased homogeneous population of intermediate sized to large lymphocytes with basophilic cytoplasm, high N:C ratio, centrally placed and round to oval nuclei. Many lymphoid cells displayed abundant intracytoplasmic magenta granules. Flow cytometry performed on the intestinal wall and lymph node aspirate revealed an expanded population of intermediate sized CD4 positive T cells which showed normal expression of CD3 but failed to express the pan T-cell marker CD5. The flow cytometry study performed on the lymph node aspirate also revealed a similar homogeneous distribution of CD4 positive T cells but show lack of CD5 expression. These findings were diagnostic for T-cell lymphoma/leukaemia. The presence of large granular lymphocytes coupled with the flow cytometry findings supported the diagnosis of a large granular lymphocyte lymphoma (CD4 positive LGLL).
The cat received combination chemotherapy protocol with some reduction in tumour after 6 weeks of treatment. Procarbazine was added to the protocol in week 8 when the tumour progressed in size with additional enlargement of mesenteric lymph nodes. The cat continued to lose weight throughout the treatment period and was euthanised after approximately 9 weeks of treatment.
Most feline T-LGL proliferations primarily expressed a CD3(+)/CD8(+) phenotype, although occasional feline LGLs had a CD4-CD8- phenotype whilst sparse feline LGL cases revealed CD4+ clonal T-LGL expansion. Median survival time for cats with LGL that were treated was 57 days. Feline LGL neoplasia presented as an aggressive disease that was characterised by primary small-intestinal involvement and an aggressive biological behaviour with an associated poor prognosis and minimal response to chemotherapy.