OBJECTIVETo study the clinicopathologic features, diagnosis and differential diagnosis of intestinal natural killer (NK)/T-cell lymphoma.

METHODSThe clinical features, histopathology, immunohistochemical findings and follow-up data of 14 cases of intestinal NK/T-cell lymphoma were retrospectively reviewed.

RESULTSThe male-to-female ratio was 9:5. The medium age of patients was 45 years. The sites of involvement included small intestine (6 cases), colon (6 cases) or both (2 cases). The main clinical manifestations were an abdominal mass, other gastrointestinal symptoms such as abdominal pain, as well as systemic symptoms such as fever and cachexia. Intestinal perforation complicated by acute peritonitis might occur in advanced disease. Histologically, the intestinal wall showed full-thickness infiltration by medium-sized atypical lymphoid cells with pleomorphic nuclei, prominent inflammatory background, angiocentric/angiodestructive growth pattern and coagulative necrosis. Immunohistochemical study showed that the tumor cells were positive for CD3ε, CD43, CD56, granzyme B and perforin. They were negative for CD20, CD79α and MPO. In-situ hybridization for Epstein-Barr virus encoded RNA (EBER) showed negative signals. A high proliferative index was demonstrated by Ki-67 immunostaining. Follow-up data of 8 cases were available, with duration of follow up ranging from 0.5 to 36 months. Five patients died within 20 months.

CONCLUSIONSExtranodal NK/T-cell lymphoma, nasal-type primarily involving intestine is rare and tends to carry an aggressive clinical course. The relatively non-specific clinical manifestations of intestinal NK/T-cell lymphoma may result in misdiagnosis in some cases. A comprehensive evaluation of clinical manifestations, pathologic features and immunohistochemical findings is essential for definitive diagnosis.