Intravascular large T-cell or NK-cell lymphoma: a rare variant of intravascular large cell lymphoma with frequent cytotoxic phenotype and association with Epstein-Barr virus infection.

Most cases of intravascular large cell lymphoma have a B-cell phenotype, but rare T-cell and natural killer (NK)-cell variants have been reported. We describe the clinicopathologic features of 4 patients (M:F=3:1; age range: 63 to 87; median age: 65) with intravascular large NK/T-cell lymphoma. The skin was the site of presentation in all patients (leg: 1 case; trunk: 1 case; trunk and extremities: 2 cases). Two patients had lesions confined to the skin; in 1 case concomitant involvement of the brain was detected and in 1 case no further studies were carried out. Immunohistology showed positivity for cytotoxic markers in 3/4 cases. One case had an NK phenotype similar to NK/T-cell lymphoma, nasal-type, whereas the other cases could not be precisely classified into specific categories (peripheral T-cell lymphoma, NOS). One of these cases was negative for cytotoxic markers and was positive only for CD2 and CD3 epsilon. Association with Epstein-Barr virus (EBV) was demonstrated in 2 cases by in situ hybridization, whereas 1 case was negative. All our patients had aggressive disease and died between 2 weeks and 7 months from presentation. Analysis of our cases and of those published in the literature shows that intravascular large NK/T-cell lymphoma is a rare, aggressive lymphoma with variable phenotypic features, frequent expression of cytotoxic proteins, true NK-cell phenotype and association with Epstein-Barr virus infection, and common presentation in the skin. Homogeneous studies on larger number of patients and reevaluation of cases published with incomplete phenotypic data would be necessary to gather more information on this extremely rare type of lymphoma.