Immunophenotypic and genotypic characterization of nasal lymphoma with polymorphic reticulosis morphology

Nasal lymphoma with polymorphic reticulosis (PR) morphology is now categori zed as T/natural killer (T/NK) cell lymphoma. In this study, immunophenotyp es and genotypes of proliferating cells in 21 cases with PR were examined. The patients included 13 men and 8 women ranging in age from 20 to 74 (medi an 37) years. All patients presented with lesions in the upper respiratory tract, mostly in the nasal cavity, Histological specimens obtained from the primary lesions (19 cases) and metastatic cervical lymph nodes (2 cases) w ere used for analyses. Histologically, polymorphous proliferation was found in 20 cases, and these were thus diagnosed as PR, A monomorphous pattern w as found in the remaining last case. Immunohistochemical analysis revealed that the proliferating cells were CD56 (123C3)(+) and/or CD16 (2H7)(+), TIA -I+ and frequently stained CD3 epsilon(+), Tumor cells were frequently stai ned positively with monoclonal antibodies (mAbs) for T lymphocytes, but wer e negative for T-cell receptor (TCR) beta and delta chain expression. In si te hybridization analysis using an Epstein-Barr virus-encoded early RNA I ( EBER-I) probe revealed positive signals in 13 of the 15 cases examined. Sou thern blotting analysis for clonality of the Epstein-Barr virus (EBV) genom e in IZ positive cases confirmed the presence of monoclonal proliferation i n 7 cases. The pattern of TCR gamma chain gene rearrangement was examined b y PCR analysis of DNA from tumor tissues by the denaturing gradient gel ele ctrophoresis method. The results demonstrated no clonal rearrangement in an y of the 21 cases examined, including 7 cases with proven clonal proliferat ion of EBV-infected cells, indicating the absence of T-cell clones. Our fin dings strongly suggested that nasal T-cell lymphoma is in fact a NK cell ly mphoma. (C) 1999 Wiley-Liss, Inc.