Infiltrating myoepithelial carcinoma of the breast, a case report and cytologic-histologic correlation

Here we present the cytologic findings from a case of infiltrating myoepithelial carcinoma of the breast in a 52-year-old female and provide a histologic correlation with the subsequent biopsy and mastectomy specimens. While the cytology specimens displayed more myoepithelial cellular heterogeneity than was present on histology, a number of cytologic features including hypercellularity, pleomorphic spindle cells, and mitotic activity correlated well with the histopathology.The role of fine needle aspiration in the diagnosis of mammary myoepithelial carcinoma, in this case, was to establish malignancy rather than to arrive at a specific diagnosis, as a number of different entities potentially can mimic this neoplasm on cytologic specimens.Myoepithelial carcinoma of the breast (MEC), a lesion composed purely of malignant myoepithelial cells, remains a rarely reported phenomenon. At this time, about 30 cases of pure, or de novo, MEC have so far been reported in the medical literature. While the histologic, immunohistochemical, and even ultrastructural features have been well described, a definite diagnosis of MEC based on cytology alone remains challenging. Herein, we report the case of a pure, infiltrating myoepithelial carcinoma of the breast while providing a correlation between the histologic and cytologic findings. We furthermore discuss the potential role of fine needle aspiration (FNA) within the diagnostic work-up of this neoplasm in relation to other spindle cell lesions of the breast.The patient was a 52-year-old white female who had noticed a gradually enlarging lump in her left breast for the past five years. On physical examination, the mass was well-circumscribed, non-tender to palpation, and freely mobile. Subsequent mammography revealed a complex 7-cm mass in the upper outer quadrant of the left breast. Fine needle aspiration, core needle biopsies, and finally a simple mastectomy with sentinel node biopsy were performed over the next several months. The