Abstract:

Case Description: A 77-year-old male with a history of prostate cancer presented with a 3-monthlong pruritic breast mass. There was no associated breast pain, discharge, or bleeding and no family history of breast cancer. Physical exam demonstrated a 3 cm, firm, mobile, skin colored nodule of the right breast immediately medial to the areola. No adenopathy was present. The mass was confirmed by breast ultrasound and mammogram. Two side-by-side 4mm punch biopsies revealed infiltrative dermal nests of epithelioid cells with large, hyperchromatic nuclei and eosinophilic cytoplasm. Many scattered tumor cells contained clusters of intracytoplasmic vacuoles scalloping the nucleus. No epidermal or adnexal connection was identified. By immunohistochemistry, the tumor cells were positive with androgen receptor, estrogen receptor, progesterone receptor, and Cam 5.2. There was focal staining with BerEP4. D2-40, p63, and GCDFP-15 were negative. The overall histopathologic and immunohistochemical features supported the diagnosis of breast carcinoma with sebaceous and apocrine features, rather than a primary cutaneous sebaceous carcinoma. Staging with CT chest/abdomen/pelvis was negative for metastases. He underwent right mastectomy with sentinel lymph node biopsy. Lymphovascular invasion was identified in the mastectomy specimen. Tumor margins were negative. One axillary sentinel node contained tumor cells. The patient is currently receiving adjuvant anti-hormonal therapy 3 months after surgery. Germline testing revealed a CHEK2 gene variant. Discussion: Sebaceous carcinoma of the breast is a rare variant of primary breast carcinoma with few reported cases, some with aggressive metastatic disease. As it may mimic primary cutaneous sebaceous carcinoma, it is important to recognize, differentiate, stage, and treat appropriately. Sebaceous carcinoma of the breast should be considered in tumors resembling primary cutaneous sebaceous carcinoma localized to the breast.

Financial Disclosure:
No current or relevant financial relationships exist.

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Kevin Severson, MD