Mucosa-associated lymphoid tissue lymphoma coexisting with epithelioid granulomas in the stomach of a patient with systemic sarcoidosis.

Malignant lymphoma arising in the stomach of a 23-year-old Japanese man with systemic sarcoidosis is presented. The patient was followed because of systemic sarcoidosis involving the lungs, eyes, and lymph nodes. Biopsy specimens from the stomach were repeated because of recurrent epigastralgia and multiple ulcerations. Some of the specimens revealed epithelioid granulomas with no caseous necrosis, which confirmed gastric involvement of sarcoidosis. Three years after the initial diagnosis, biopsy specimens taken from the stomach were diagnosed as malignant lymphoma of the large cell type. The resected stomach revealed multicentric mucosa-associated type malignant lymphoma of low-grade B cell type, with foci of high-grade transformation coexisting with numerous epithelioid granulomas with no caseous necrosis. Epithelioid granulomas were observed in all the respected lymph nodes, liver, and appendix, which had been obtained at operation, whereas malignant lymphoma was limited to the stomach. Helicobacter pylori (H. pylori) infection was also observed in the stomach. Consequently, the present report is a rare case of coexistence of malignant lymphoma and involvement of sarcoidosis in the stomach. Both H. pylori infection and active sarcoid nodules may play a role in the development of malignant lymphoma, although the exact mechanism remains unclear.