A Rare Case of Extramedullary Multiple Myeloma Presenting as Masses on the Breast and Chest Wall Complicated with Sjogren's Syndrome

Multiple myeloma (MM) in the breast has been rarely documented. However, there are no reports on concurrent masses of chest wall soft tissue and breast as the primary symptoms for MM. Herein, we report a case of a 68-year-old woman presented with masses in her right breast and chest wall for 1 month. She recalled having xerophthalmia and xerostomia for 2 years without taking any test to search for the cause of these symptoms. Ultrasonography (US) and computed tomography (CT) examination revealed masses in the right breast and chest wall. Both lesions of the breast and chest wall were confirmed to be plasma cell tumors by ultrasound-guided puncture biopsy and MM was confirmed by bone marrow examination. Meanwhile, Sjogren's syndrome (SS) was diagnosed by the positive expression of antibodies against antinuclear, Ro/SSA and La/SSB. After three courses of chemotherapy for MM, the symptoms of SS were significantly alleviated and the masses in the chest wall and breast disappeared.