Abstract

Breast cancer has the highest rate of cutaneous metastasis among all solid-organ malignancies. Almost all cases of cutaneous metastases of breast cancer are in females though, reflecting the statistic that <1% of primary breast carcinomas are diagnosed in males. Controlled for stage, males and females with breast carcinoma have similar survival rates, but men are often diagnosed at a more advanced stage due to a lack of screening and likely due to lower awareness of breast cancer among male patients. We present a case of a 73-year-old male with a history of invasive ductal carcinoma of the breast five years prior. He had been treated with Tamoxifen for four years but did not complete his course of therapy. He now presented with a skin-colored nodule near the edge of his mastectomy scar. Histopathologic examination of the biopsy specimen demonstrated an infiltrative tumor centered in the dermis and separated from the overlying epidermis by a Grenz zone, composed of glandular structures and cords of cells in a desmoplastic stroma. The tumor cells were positive for GATA3, CK7, ER, and PR; they were negative for CK 20, HER2, and TTF-1. We present this case as a reminder to include breast carcinoma in the differential diagnosis when evaluating metastatic carcinomas of unknown primaries in male patients, as well as to review the differential diagnoses, the role of relevant immunohistochemical stains, and the potential diagnostic pitfalls.

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