A Case Report of Multiple Pigmented Perineal Hidrocystomas

Abstract

Apocrine hidrocystomas occur most commonly as solitary nodules on the face and neck. Case reports of patients with multiple lesions on the face, particularly in the periorbital region, have been described. They present as cystic, translucent, blue or brown papules or nodules. The color is attributed to the Tyndall effect, as pigment such as melanin or hemosiderin has rarely been demonstrated within the lesions. We present a 43‐year‐old Caucasian female with over thirty blue‐gray macules on her perineum and vulva. The patient was unaware of the lesions though she noted perineal and inguinal pruritus after exercise. Punch biopsy showed a cluster of cysts within a loose stroma, located in the deep dermis. The cysts were lined by a single layer of flattened cells with eosinophilic cytoplasm and focal areas of papillation and decapitation secretion. A peripheral layer of myoepithelial cells was present. The epithelium contained brown pigment confirmed to be melanin by Fontana‐Masson stain. Iron stain was negative. GCDFP‐15 (gross cystic disease fluid protein) labelled the epithelial cells. S‐100 and Mart‐1 immunohistochemical stains were negative. Unusual features of this case include the anatomic site, number of lesions, and demonstration of melanin as the cause of the clinical pigmentation.