Atypical Presentation of Extramedullary Plasmacytoma

Abstract

Background: Plasmacytomas are monoclonal proliferations of plasma cells that typically affect the intramedullary axial skeleton. Imaging findings of an extramedullary plasmacytoma on radiograph and computed tomography can be nonspecific and can resemble other entities such as lymphoma, metastases, chondrosarcomas, or giant cell tumors.

Case report: A 60-year-old female with a medical history of partial complex seizures, hypertension, diabetes, glaucoma, and hyperlipidemia presented with complaints of superficial abdominal pain associated with erythema and swelling for 3 weeks. Computed tomography of her abdomen at time of presentation revealed a 5.8 × 2.7-cm irregularly marginated soft-tissue density just below the umbilicus with an adjacent defect in the midline rectus abdominis. The final pathologic diagnosis was extramedullary plasmacytoma. Treatment during the next year included local radiation, systemic chemotherapy, and an autologous peripheral blood stem cell transplant. Three years after initial diagnosis, the patient presented to the emergency department, and testing revealed new plasmacytomas. The decision was made to proceed with palliative care.

Conclusion: This case is a unique example of a patient with an extramedullary plasmacytoma with no diagnostic signs of multiple myeloma.

Keywords: Multiple myeloma; plasmacytoma; soft tissue neoplasms.

Figure 1

Contrast-enhanced axial computed tomography images show a well-defined soft tissue mass just below the umbilicus.

Figure 2

Radiographs demonstrate a moth-eaten/permeative pattern medially in the distal left femoral metadiaphysis with overlying cortical erosions and periosteal reaction.