Metastatic Mammary-Like Adenocarcinoma of the Vulva Responding to Cyclin-Dependent Kinase (CDK) Inhibitor: A Case Report and Literature Review.

Mammary-like adenocarcinoma originating in the vulva is extremely rare, even rarer when metastasized at diagnosis. It may arise from the primitive mammary ridge or mammary-like glands of the skin in the anogenital region. We report a case of a 47-year-old woman with diffuse bone metastasis and a vulvar lesion compatible with mammary-type adenocarcinoma, with no evidence of primary breast cancer. Systemic treatment followed protocols for hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer, using an aromatase inhibitor and ribociclib, resulting in a favorable clinical and metabolic response. Documenting this case contributes to the understanding and clinical management of this rare neoplasm.