Obstructing plasmacytoma of the duodenum: first manifestation of relapsed multiple myeloma.

A patient with an obstructing, annular duodenal neoplasm is described. Percutaneous fine needle aspiration biopsy, and biopsy performed through an endoscope, confirmed that the lesion was an extramedullary plasmacytoma. The patient had been in clinical remission from multiple myeloma for the preceeding 13 months. Radiation therapy resulted in cessation of symptoms including gastrointestinal blood loss. After 5 months, recurrent obstructive symptoms and melena led to surgical extirpation of the tumor, with relief of all symptoms.