EXTRAMEDULLARY PLASMACYTOMA: A RARE PRESENTATION

Abstract

TOPIC: Disorders of the Mediastinum TYPE: Medical Student/Resident Case Reports INTRODUCTION: Extramedullary plasma cell tumors are unusual. Their presence in the breast tissue is extremely rare. We present a case of incidental diagnosis of a primary extramedullary lesion in a previously healthy female. CASE PRESENTATION: 45-year-old female presented with a several-week history of persistent, sharp back pain radiating to the epigastric region associated with abdominal pain and worsening numbness of the left lower extremity. She complained of a growing mass over her sternal region that she noticed five months prior. Vital signs were within normal limits, and physical exam noted a large, non-mobile, firm nodule located over the sternum. Bloodwork was unremarkable. Computed Tomography of the abdomen and pelvis revealed multiple bulky masses involving the anterior chest wall, skeleton, pleural space, and vertebral bodies (T4 and T5) with extension to the spinal canal in addition to hepatosplenomegaly. Magnetic Resonance Imaging of the spine revealed moderate cord compression at T3-T4, with no acute neurosurgical intervention recommended. Biopsy of the anterior chest wall mass revealed a plasma cell neoplasm with plasmablastic features, and flow cytometry noted approximately 46% cytoplasmic lambda light chain restricted plasma cells with expression of CD38, CD19, CD20, CD56, and CD117 with negative CD45. Bone marrow biopsy confirmed plasma cell myeloma, with the neoplastic cells in both biopsies morphologically identical. The patient was diagnosed with multiple myeloma with cord compression and started on radiation and chemotherapy. 11 months after treatment initiation, she presented to our office with a 2cm mobile, firm, irregular mass in the upper outer quadrant of the right breast and a mass in the lower inner left breast confirmed by mammogram. There was no associated nipple discharge, pain, and weight loss. Core biopsy of the masses diagnosed plasma cell myeloma, with the tumor cells morphologically similar to those of the anterior chest wall mass. DISCUSSION: Plasmacytoma is a malignant proliferation of plasma cells[1,2,3] and is considered to be extramedullary when situated outside the bone marrow. It may occur in the lungs, gastrointestinal tract, spleen, pancreas and very rarely in the breast [4-7]. The likelihood of diagnosing a breast extramedullary plasmacytoma is approximately 0.01%[4,5,6]. Confirmation of the diagnosis is by the demonstration of monoclonal plasma cells and plasma cell markers, such as CD38 from immunohistology. Bone marrow biopsy is required to confirm or rule out the presence of plasma cells in the bone marrow. Radiation therapy over a course of four weeks is the treatment of choice [8]. Smaller lesions may be treated with surgery alone. CONCLUSIONS: Extramedullary plasmacytoma involving the breast is a very rare, underdiagnosed form of multiple myeloma, and should be part of the differential for breast masses to avoid misdiagnosis and improve outcomes. REFERENCE #1: Carson C P, Ackerman L V, Malty J D. Plasma cell myeloma. Annals of Clinical Pathology. 1955;25:849–888. [PubMed] [Google Scholar] REFERENCE #2: Cutler C W J. Plasma cell tumour of the breast with metastases. Annals of Surgery. 1934;100:392–395. [Google Scholar] REFERENCE #3: Booomberg TH, Glees JP, Williams JE. Bilateral breast lumps; an unusual feature of extramedullary plasmacytoma. Br J Radiol. 1980;53:498–501. [PubMed] [Google Scholar] DISCLOSURES: No relevant relationships by Muhammad Hanif, source=Web Response No relevant relationships by Samia Hossain, source=Web Response No relevant relationships by SANA MULLA, source=Web Response No relevant relationships by Ruqqiya Mustaqeem, source=Web Response No relevant relationships by Rajesh Thirumaran, source=Web Response No relevant relationships by Vihitha Thota, source=Web Response