[Gastric plasmacytoma as an uncommon cause of upper gastrointestinal bleeding].

Gastric plasmacytoma is an infrequent form of presentation of monoclonal gammopathy that, if ulcerated, can cause upper gastrointestinal bleeding. This entity is usually localized but may progress to multiple myeloma or other forms of monoclonal gammopathy. Differential diagnosis should be performed with other monoclonal gammopathies, based on laboratory and histological criteria, as well as with other gastric tumors such as adenocarcinoma, gastrointestinal stromal tumors, neuroendocrine tumors and lymphomas. Differential diagnosis can be based on radiological and endoscopic characteristics, although definitive diagnosis will undoubtedly be based on histological study and immunohistochemical techniques. We describe the case of a male patient who underwent investigations for upper gastrointestinal bleeding and iron deficiency anemia. The final diagnosis was multiple myeloma associated with gastric plasmacytoma.