Rare neoplasm of the breast

Abstract

Background: In breast tumors, a histological distinction is made between benign and malignant findings as well as lesions with uncertain biological potential. While 94–97% of all symptomatic breast findings are benign, malignant lesions are of highest clinical relevance. Over 90% of malignant breast tumors are nonspecial type (NST) or lobular carcinomas. The remainder is comprised of a heterogeneous group of rare tumors, each representing up to 1% of cases. Some of these mammary findings exhibit a specific clinical presentation or require specialized diagnostic or clinical management. Objectives: Presentation of selected rare breast tumors and their specific features in diagnostics and treatment. Materials and methods: Evaluation of current evidence and treatment recommendations. Results: Important rare breast tumors include phyllodes tumors, which can be benign, borderline, or malignant, as well as sarcomas, lymphomas, neuroendocrine neoplasms of the breast and metaplastic breast carcinomas. Sarcomas and lymphomas can occur both primarily and secondarily, or as metastases in the breast. Notable examples include radiotherapy-associated angiosarcoma and breast implant-associated anaplastic large-cell lymphoma. The treatment of neuroendocrine tumors largely follows the approach used for NST breast carcinomas. Special treatment considerations must be taken into account for other rare entities.