Idiopathic ulcer of the small bowel containing numerous plasma cells: case resembling mucosa-associated lymphoid tissue lymphoma.

Idiopathic ulcer of the small bowel is a poorly recognized entity. Herein is reported a case of idiopathic ulcer of the jejunum containing numerous lymphoplasmacytoid infiltrates and mimicking mucosa-associated lymphoid tissue (MALT) lymphoma. An 82-year-old Japanese woman presented with nausea and vomiting. Following diagnosis of submucosal tumor, partial jejunal resection was performed. Macroscopically the resected specimen contained multiple small shallow ulcers. Histologically the lesion was composed of numerous plasma cells mixed with lymphocytes and histiocytes. Immunohistological study revealed that the plasma cells contained polytypic intracytoplasmic immunoglobulins. The patient remained free of disease after 36 months. Marginal zone B-cell lymphoma of MALT-type arising from small intestine occasionally shows prominent plasma cell differentiation. The present case demonstrates that idiopathic ulcer of the small bowel should be added to the differential diagnosis of MALT-type lymphoma of the small bowel.