Mucosa-associated lymphoid tissue lymphoma of the thymus associated with Sjögren's syndrome: report of a case.

A 68-year-old Japanese man with Sjögren's syndrome was pointed out to have a nodular shadow in the anterior mediastinum. The tumor was resected under video-assisted thoracoscopy and it was pathologically diagnosed to be thymic mucosa-associated lymphoid tissue (MALT) lymphoma. There has been no recurrence for 17 months after surgery. Mucosa-associated lymphoid tissue lymphoma of the thymus is rare, and its pathological diagnosis requires sufficient knowledge and experience. Since thymic MALT lymphoma is distinct from MALT lymphoma of other sites in several ways, including gene abnormalities and geographic distribution, an alternative oncogenic pathway and the influence of racial and/or environmental factors must be considered to be involved. However, since the number of reported thymic MALT lymphomas is limited, these issues are still unclear. The accumulation of further similar cases will help to elucidate various issues concerning thymic MALT lymphoma associated with Sjögren's syndrome.