Primary Apocrine Adenocarcinoma of the Vulva: A Report of a Rare Case.

Primary apocrine adenocarcinoma of the vulva is a rare and aggressive malignancy that typically presents as an irregular vulvar lesion with associated dermatologic changes. Diagnosis can be challenging due to significant clinical and histopathologic overlap with other vulvar adenocarcinomas as well as metastatic disease. We present the case of a 63-year-old postmenopausal woman diagnosed with primary apocrine adenocarcinoma of the vulva. The patient's prior history of breast cancer created a diagnostic dilemma, as it was initially unclear whether the lesion represented metastatic breast carcinoma or a primary vulvar malignancy. Histopathologic evaluation with immunohistochemical analysis demonstrated strong androgen receptor positivity, negative estrogen receptor and progesterone receptor staining, strong GCDFP-15 positivity, and strong CK7 positivity. This profile supported the diagnosis of primary vulvar apocrine adenocarcinoma, allowing for appropriate surgical management and successful excision of the lesion. This case highlights the diagnostic complexity of vulvar adenocarcinomas and underscores the importance of systematic clinicopathologic evaluation, particularly in patients with a history of malignancy.