Sebaceous Carcinoma of the Breast: A Case Report and Review of the Literature.

Sebaceous carcinoma of the breast is a rare and poorly understood variant of metaplastic breast carcinoma. Its histogenesis, clinical behavior, and optimal management remain unclear due to the limited number of reported cases. We report the case of a 78-year-old woman presenting with a six-month history of a right axillary mass and inflammatory changes in the right breast. Clinical and radiologic assessments indicated an advanced-stage lesion. Histological analysis from a core needle biopsy revealed solid nests and tubules with sebaceous differentiation. Immunohistochemistry confirmed a triple-negative profile, with high proliferative activity. The patient received neoadjuvant chemotherapy without clinical improvement. Disease progression was noted despite a switch to a platinum-based regimen, followed by further deterioration after additional treatment. The patient was eventually lost to follow-up. This case highlights the aggressive nature and treatment resistance of this carcinoma and underscores the need for further investigation to better define its characteristics and guide therapeutic strategies.