Feline intestinal T-cell lymphoma: assessment of morphologic and kinetic features in 30 cases

Intestinal lymphoma is a common entity in cats. According to WHO-REAL classification system, after immunophenotyping B-cell lymphomas are further categorized according to their morphology, while those deriving from T-cells are collectively considered in the intestinal T-cell lymphoma (ITCL) category. In this study we evaluated 30 feline ITCL out of 77 cats with gastrointestinal lymphoma. Neoplastic lesions were composed of predominantly small (n = 21) or medium-to-large anaplastic (n = 9) cells. Different patterns of tumor growth were observed. Starry-sky pattern was evident 7 cases (23.3%), fibrosis in 18 cases (60%) and neovascularization in 19 cases (63.3%). The cell proliferation index (assessed by MIB-1 immunohistochemistry) ranged from 0.21% to 66.91%. Mean MIB-1 index was 3.49% within the first 33° percentile, 18.31% within the second 33° percentile, and 40.16% within the third 33° percentile (p < 0.000001). Microscopic and kinetic features provided evidence that ITCL exhibits in cats a spectrum in cytological composition and growth patterns, that could putatively reflects differences in biologic behavior