Abstract
INTRODUCTION AND IMPORTANCE: Solitary plasmacytoma of the breast is an extremely rare manifestation of plasma cell neoplasms, predominantly seen in the bone marrow and commonly associated with multiple myeloma. When it occurs as an isolated lesion in the breast, it presents unique diagnostic and therapeutic challenges due to its rarity and clinical similarity to other breast conditions. CASE PRESENTATION: We report a case of a 60-year-old female presenting with a gradually enlarging mass in her right breast over six months. Physical examination revealed a firm, non-tender, mobile mass without skin or nipple changes, and no axillary lymphadenopathy. Mammography showed a well-defined mass, and fine needle aspiration biopsy indicated a plasmacytoma. A comprehensive workup including blood tests, bone marrow biopsy, and PET-CT ruled out multiple myeloma. Histopathology confirmed a solitary plasmacytoma with CD38 and CD138 positivity. The patient underwent surgical excision of the mass followed by adjuvant radiotherapy, resulting in no recurrence or progression over a two-year follow-up period. CLINICAL DISCUSSION: This case underscores the importance of considering solitary plasmacytoma in the differential diagnosis of breast masses. Accurate diagnosis through histopathological examination and immunohistochemistry, followed by appropriate surgical and radiotherapeutic management, can lead to favorable outcomes. CONCLUSION: Continuous follow-up is essential to monitor for potential recurrence or progression. This case contributes to the limited literature on this rare entity and highlights the need for further research to develop standardized management protocols.