Primary extramedullary plasmacytoma (EMP) is a solitary tumor that arises outside the bone marrow in patients without clinical evidence of coexisting multiple myeloma. EMP represents only 4% of all patients with plasma cell malignancies. The tumor generally occurs in the submucosal tissue of the upper airway or oral cavity. 10% of all EMP occur in the gastrointestinal tract. Only 8 cases of EMP in the duodenum have been reported in literature.
The authors present a case of EMP in the duodenum in a 53 year old men. The tumor was initially misdiagnosed as desmoid tumor. With a combined treatment of surgery and chemotherapy complete remission for 2 years was achieved, followed by a dissemination of the tumor in the testis, mandibular bone and ribs.
EMP is a rare differential diagnosis of an intraabdominal tumor. Diagnosis is difficult, and in most reported cases it is confirmed only postoperatively after immunohistochemical staining. Combined treatment of surgery and chemotherapy seem to offer the best potential for cure.