Primary extramedullary plasmacytoma of the omentum associated with recurrent adenocarcinoma of the colon: first case report.

Extramedullary plasmacytomas are rare tumors, with 272 cases reported in the literature in English. Less than 10 per cent of these are located in the gastrointestinal tract. This report documents the first primary plasmacytoma of the omentum in association with a recurrent colonic adenocarcinoma. Extramedullary plasmacytoma, a B cell neoplasm, characteristically arises in areas containing lymphoid tissue. In our case the tumor most likely arose in a lymph node or nodes in the omental fat, with subsequent replacement of the entire greater omentum and involvement of the colonic serosa by direct extension. Although the extent and nature of the association between myeloma and carcinoma remain obscure, a review of the literature suggests that such association may occur more frequently than has been supposed. Further investigation would appear to be warranted.