Early extramedullary plasmacytoma confined to the lamina propria of the gastric mucosa: case report.

A case of early gastric plasmacytoma in a 51-year-old woman is reported. The demonstration of monotypic IgM-kappa immunoglobulin in biopsy specimens by an immunoperoxidase technique contributed to the histological diagnosis. The patient had non-ulcerative lesions (of approximately 15 x 16 cm) of a superficially spreading type of gastric plasmacytoma. Extensive histological analysis of the resected stomach showed the IgM-kappa monoclonal proliferation of plasmacytic tumor cells to infiltrate merely into the lamina propria of the gastric mucosa and not to extend deeply into the submucosa, proper muscle and serosa of the stomach.