Mott cell tumor of the stomach with Helicobacter pylori infection.

A plasma cell tumor of the stomach with unusual histology is reported. Macroscopically, the tumor formed two ulcers in the gastric body, and microscopic examination revealed proliferation of plasma cells producing immunoglobulin G kappa monotypic immunoglobulin, with metastatic infiltration in some perigastric lymph nodes. Most of these plasma cells had various-sized Russell bodies in the cytoplasm; hence the tumor may be called Mott cell tumor. The Russell bodies showed a strong affinity to concanavalin A by lectin immunohistochemistry, compared with those in reactive Mott cells. In addition, Helicobacter pylori (H. pylori) infection was proved by Gimenez stain and immunohistochemistry. The mixture of some centrocyte-like cells and presence of reactive lymph follicles with follicular colonization by tumor cells suggest that this lesion may be a variant of mucosa-associated lymphoid tissue lymphoma in association with H. pylori infection. The patient has shown no evidence of recurrence of the tumor after 11 years of follow up.