A 27-years-old woman with an untreated upper outer quadrant breast mass for 1-year was referred to our cancer hospital for surgical evaluation of increasing breast pain. She had no history of bone pain, weight loss, fatigue, fever or other systemic complaints, and no family history of breast cancer. On physical examination there were no skin changes or nipple discharges, and the mass was firm, freely moveable, and nontender. Mammography confirmed a well-defined 5.2 cm mass in upper outer quadrant of the right breast. There were no satellite lesions. Laboratory tests including complete blood count, total protein, glucose, hepatic and renal function panels were normal. Because primary breast carcinoma was suspected patient agreed to a modified radical mastectomy. There was no extension from the capsulated masses to pectoral muscles or chest wall, and no axillary lymph node involvement.
Gross pathology examination revealed a soft, pale, encapsulated gritty mass surrounded by normal breast tissue, measuring 5.0 cm × 4.0 cm × 2.5 cm. Histopathological examination showed an infiltrating ductal carcinoma complicated by an extramedullary plasmacytoma divided by fibrous tissue in one section (Figure ). Immunohistochemical stains were negative for estrogen, P170, and progesterone receptors. Her-2 was negative (Figure ). Nuclear prognostic marker (Ki-67) showed 25% to 50% nuclear expression. Topoisomerase-IIα (+<5%), CylinD-1, Cytokeratin, and S-100 were negative. The tumor cells were strongly positive for light kappa chains (Figure ), and negative for light lambda, delta, and my chains.
Extramedullary plasmacytoma and breast cancer were divided by fibrous tissue. (Hematoxylin & Eosin×40).
Immunohistochemical stain for Her-2 was negative ×40.
Plasma cells are diffusely and strongly positive for light kappa chains ×200.
After the surgery and pathologic findings, serum immunoglobulins were measured and found to be: IgG 10.03 g/l (8.0–16 g/l), IgA 1.34 g/l (0.7–3.3 g/l), IgM 1.44 g/l (0.5–2.2 g/l). No Bence Jones or other M components were detected in the urine. Serum calcium and phosphorus were normal. Posterior iliac crest bone marrow biopsy was negative for plasma cells. PET and CT scans, except for absence of the right breast, did not detect other lesions.
The patient was offered and accepted chemotherapy and radiotherapy based on previous research results about infiltrating ductal carcinoma and case reports about extramedullary plasmacytoma.