Clinicopathological analysis of sinonasal malignant lymphoma in an HTLV-1 endemic area in Japan -special focus on primary sinonasal diffuse large B-cell lymphoma-

The present study investigated histological subtypes of lymphoma in patients newly diagnosed with malignant lymphoma in the human T-cell leukemia virus type 1 (HTLV-1) endemic area of Japan, and further analyzed the clinicopathological features and clinical outcomes of patients with primary sinonasal lymphoma. We retrospectively examined 151 patients aged 18-90 years in Fukuoka, Japan. Subtypes of lymphoma were determined according to the WHO classification. Among the 151 patients, 104 were diagnosed with malignant lymphoma, including 96 at the time of initial diagnosis. Ninety-two of the 96 lymphomas (96%) were non-Hodgkin lymphoma. Mature B-cell neoplasms comprised 78% (n = 75). Primary lymphoma of the sinonasal cavity was found in six patients (6%). The histological subtype of sinonasal lymphoma was diffuse large B-cell lymphoma (DLBCL) in all six tumors. Furthermore, overall survival was significantly different among three distinct DLBCL patient groups, including primary sinonasal lymphoma patients (p = 0.0016; 3-year overall survival: sinonasal DLBCL group, 53%; DLBCL of the CNS group, 0%; other DLBCL group, 83%). Our study suggests that primary DLBCL of the sinonasal tract is a distinct disease entity of DLBCL.