A case of mammary gland-like adenocarcinoma involving the vulva

Background : Herein, we present a case of a rare case of mammary gland-like adenocarcinoma of the vulva. Case : A 56-year-old woman presented with a fixed hard mass, 5 cm in diameter, on the right side of the vulva that she had first noticed a year earlier. Examination also showed multiple enlarged lymph nodes in the pelvis. Vaginal cytology revealed adenocarcinoma cells of the Indian file pattern, and biopsy revealed findings consistent with scirrhous carcinoma of the breast. Immunostaining revealed positive staining for both estrogen and progesterone receptors, and the diagnosis of vulvar adenocarcinoma (MGA) stage 4B was made. Conclusion : Mammary-like glands have been known to exist in the normal vulvar skin, however adenocarcinoma arising from these mammary-like gland structures is extremely rare. In terms of the histopathology, these are many reported cases of cancer arising from these glands that resemble scirrhous carcinoma of the breast, and it may be a challenge to differentiate these tumors from metastatic adenocarcinoma of the breast. The current report provides a detailed report of a case of vulvar adenocarcinoma arising from the mammary-like gland structures, in which the diagnosis was established by immunohistochemistry.