Irvin et al. defined the criteria for diagnosing this disease [2]. When an in situ component is not present, and in the absence of concurrent breast carcinoma, the following should be sufficient to categorize the lesion of primary vulvar origin: (1) a morphologic pattern consistent with breast carcinoma; (2) the presence of estrogen and progesterone receptors; and/or (3) positivity for common breast cancer markers such as epithelial membrane antigen, carcinoembryonic an­tigen, and glandular keratins. The gene discussed is CEACAM5; the disease is breast carcinoma.