Biclonal Extramedullary Plasmacytoma Arising in the Peritoneal Cavity : Report of a Case

A 70-year-old woman presented to her family physician with a high fever, abdominal pain, and vomiting. Computed tomography (CT) showed a large tumor in the peritoneal cavity, and she was admitted to our hospital about 2 weeks later for further investigations and treatment. She had undergone a right mastectomy for breast cancer at the age of 60, and had been suffering from hypothyroidism since the age of 55. She looked very ill because of the high fever, nausea, and vomiting, but no lymph node swelling was detected in the neck, maxillary, or inguinal regions. Her abdomen was distended, and a large soft tumor with a poorly defined contour was palpable in the whole abdomen, mainly confined to the lower abdomen. Laboratory analysis showed a decreased hemoglobin concentration (10.1g/dl), a normal leukocyte count (6300/mm3), and a slightly increased C-reactive protein level (total level, 3.5mg/ml). The serum transaminase levels were slightly increased, but the tumor markers such as carcinoembryonic antigen, α-fetal protein, carbohydrate antigen 15-3, and NCC-ST439 were all within the normal range. The serum total protein level was 6.5g/dl, with 43.8% albumin, 5.6% α1-globulin, 11.2% α2-globulin, 22.8% -globulin, and 16.6% γ-globulin. The immunoglobulin levels were as follows: IgG, 1680 mg/dl (normal range 870–1700), IgA, 637 mg/dl (normal range 110–410), and IgM, 29mg/dl (normal Abstract We report a rare case of extramedullary plasmacytoma, which arose either in the ileum or the ileal mesentery. A 70-year-old woman presented with a high fever and symptoms of bowel obstruction. Computed tomography and magnetic resonance imaging showed a large heterogeneous tumor in the peritoneal cavity. Serum immunoelectrophoresis revealed a biclonal increase of IgA-k and IgG-k. At surgery, we found that the parenchyma of the fragile tumor had firm communication with the ileal mesentery, and the cavity of the tumor communicated with the ileal lumen. After a temporary regression following surgery and chemotherapy, the tumor grew rapidly. Although there was no evidence of progression to multiple myeloma, the patient died of cachexia less than 4 months after surgery.