[Nasal and pharyngeal non-Hodgkin lymphomas and their relationship with Epstein-Barr virus: a report of 158 cases].

Objective: To study the clinical features, immunophenotypes and the significance of Epstein-Barr virus infection in primary nasal and pharyngeal non-Hodgkin's lymphomas in Shenyang.
Methods: One hundred and fifty eight cases of primary nasal and pharyngeal non-Hodgkin's lymphomas were included in this study. The samples were stained with haematoxylin and eosin for histological examination. Immunohistochemistry studies were performed using monoclonal antibodies, including CD3 for T-lymphocytes, CD20 for B-lymphocytes, and CD56 and CD57 for NK cells. All cases were reclassified according to the new WHO classification of lymphomas (2001). In situ hybridization detection of EBV-encoded small nuclear RNA (EBER-1) was performed in 99 cases.
Results: Overall, 101 (63.9%) of the 158 NHL were extranodal NK/T cell lymphomas (nasal type), 23 (14.6%) were nonspecific peripheral T cell lymphomas and the remaining 34 cases (21.5%) were B cell lymphomas. The primary sites of involvement were the nasal cavity (53.2%, 84/158), the tonsil (24.7%, 39/158) and the pharynx (22.1%, 35/158). Among 99 cases studied by EBER-1 in situ hybridization, a positive detection was seen in 70/71 cases (98.6%) of extranodal NK/T cell lymphoma (nasal type), 8/12 cases (66.7%) of T cell lymphoma, and 7/16 cases (43.8%) of B cell lymphoma.
Conclusions: Among primary nasal and pharyngeal NK lymphomas, extranodal NK/T cell lymphoma (nasal type) is the most common type and is strongly associated with EBV infection. The pathological diagnosis of nasal and pharyngeal lymphomas should take considerations of the anatomic sites and immunophenotypical features.