An asymptomatic sessile nodule on the scalp: nodular hidradenoma

Abstract

Hidradenoma is a relatively rare tumor of sweat gland origin. The tumors are firm dermal nodules, 5-30 mm in size, and may be attached to the overlying epidermis, which can be either thickened or ulcerated. Growth of the tumor is slow with high incidence of local recurrences after excision. A 25-year-old man presented with an asymptomatic solitary nodule on the scalp. Cutaneous examination revealed single, sessile, skin-coloured, non-tender, firm nodule on the occipital region of the scalp. No regional lymphadenopathy noted. Histopathology showed tumor located in the dermis consisting of lobules separated by fibrovascular septae. Within the lobules, tubular lumina of various sizes, cystic spaces and many proliferating blood vessels are noted. Individual tumor cells are round to polygonal with eosinophilic to clear cytoplasm. On the basis of clinical and histopathological findings, diagnosis of nodular hidradenoma (NH) was made. Nodular hidradenoma is a benign, rare adnexal neoplasm. It usually presents between the fourth and the eighth decade of life, with a peak incidence in the sixth decade. NH is well-circumscribed and is sometimes encapsulated. Malignant transformation is very rare. Surgical removal with wide margins is the treatment of choice. Present case is being reported because of its rarity in this region of scalp and sex at young age.