Occurrence of multiple lymphoepithelioma-like carcinomas and MALT-type lymphoma in the stomach: detection of EBV in carcinomas but not in lymphoma.

A multifocal lymphoepithelioma-like carcinoma and a low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT-type) were found simultaneously in the stomach of a 65-year-old patient. Carcinoma and lymphoma were intimately associated forming complexes resembling lymphoepithelial lesions at the primary gastric site and in lymph node metastases. The two tumours had developed on a background of severe chronic-atrophic gastritis of the mucosa of antrum and fundus. Autoantibodies to normal gastric glandular tissue could be demonstrated in the patient's sera. Using non-radioactive in situ hybridization (ISH), Epstein-Barr virus (EBV) sequences were detected in virtually all carcinoma cells but neither in the non-neoplastic mucosa nor in the lymphoma. These findings suggest that a focal EBV infection occurred early in the development of the carcinoma followed by a subsequent clonal expansion of the EBV-containing tumour cells. A neoplastic transformation in MALT-type lymphoma is not EBV-related but might be triggered by altered immune mechanisms.