Sebaceous carcinoma of the breast predominantly characterized by intraductal growth: a case report

BACKGROUND: Sebaceous carcinoma (SC) is frequently classified as periocular or extraocular. Extraocular SC is rare and mainly occurs in the head and neck, the major salivary glands, or oral mucosa. SC of the breast, lung, and ovary is particularly rare, and the few cases of SC of the breast predominantly exhibit intraductal growth. CASE PRESENTATION: A 47-year-old Japanese woman was referred to our hospital with accumulated polymorphic calcification in the left breast which was detected using mammography. Ultrasonography revealed an irregular 13-mm mass in the left breast, and analysis of a core needle biopsy revealed noninvasive ductal carcinoma. Total mastectomy and sentinel lymph node biopsy were performed. Histopathology demonstrated that carcinoma in situ (CIS) represented a significant lesion, and the cytoplasm of tumor cells was clear with numerous minute vacuoles. Immunohistochemical analysis demonstrated that most tumor cells expressed adipophilin. Together, these findings led to a diagnosis of SC, mainly comprising CIS. CONCLUSIONS: We encountered a rare case of SC of the breast with predominant CIS.