Malignant lymphoma in patients with rheumatic diseases other than Sjögren's syndrome: a clinicopathologic study of five cases and a review of the Japanese literature.

We conducted clinicopathologic and immunohistochemical analysis of five patients with malignant lymphoma complicating rheumatic diseases other than Sjögren's syndrome, and reviewed 26 cases of similar lesions reported in the Japanese literature over a 17-year period. All five patients were women ranging in age from 31 to 74 years (mean 55 years). Two of them fulfilled the diagnostic criteria for systemic lupus erythematosus, two for dermatomyositis and one for progressive systemic sclerosis. The use of immunosuppressive drugs before the onset of malignant lymphoma was recorded in four patients. All the biopsied or resected specimens showed non-Hodgkin's lymphoma of B-cell phenotype. Three were nodal in origin (one diffuse mixed, one diffuse large cell and one immunoblastic) and two were extranodal (one low-grade B-cell lymphoma of mucosa-associated lymphoid tissue and one diffuse large cell). In three of four cases examined, Epstein-Barr virus-encoded small RNAs were identified in a small to large number of the lymphoma cells by in situ hybridization. Our study showed that the clinicopathological features of malignant lymphomas complicating rheumatic disease in Japan were similar to those in England and the USA. Furthermore, our findings suggested no evidence for a causative association between iatrogenic immunosuppression due to methotrexate therapy and the development of EBV-related lymphoid neoplasms.