Breast myxoma presenting as a mucocele-like lesion: a rare case report with a brief review of the literature

Abstract

Breast myxoma is an exceptionally rare benign mesenchymal tumor, with only few cases reported in the literature. Its diagnosis may be challenging because of overlapping clinical, radiologic, and cytologic features with other mucin-rich breast lesions. We report a rare case of breast myxoma in a 58-year-old male, presenting with a small subareolar lesion that was initially interpreted on fine-needle aspiration cytology (FNAC) as a benign cystic lesion, possibly a mucocele-like lesion (MLL). Ultrasonography showed a well-circumscribed cystic lesion without internal solid components. FNAC yielded a jelly-like material and revealed an abundant myxoid background with scattered macrophages, but no ductal epithelial cells. Excision showed an ill-circumscribed subepithelial lesion composed of bland spindle and occasional stellate cells embedded in abundant myxoid stroma with delicate collagen bundles. Immunohistochemistry showed focal cluster of differentiation 34 positivity, supporting the diagnosis of breast myxoma. This case report highlights an important diagnostic pitfall in the evaluation of myxoid breast lesions, particularly when cytology is hypocellular and mimics MLL. Accurate diagnosis requires careful histopathologic assessment, clinicoradiological correlation, and appropriate immunohistochemical support.