Nodular Hidradenoma With Atypical Features in a Young Patient: A Case Report.

Eccrine acrospiromas, also known as hidradenomas, are rare benign tumors that develop from the eccrine sweat glands. Hidradenoma is a multilobular, nonencapsulated, well-circumscribed dermal nodule that may involve the epidermis and extend into the subcutaneous fat. The etiology and prevalence of nodular hidradenoma are not well defined, but it is noted that it can occur spontaneously or traumatically. A 22-year-old, medically healthy male patient presented to the Dermatology clinic with a painless, progressive scalp lesion that had been bleeding on manipulation for the previous three years. On examination, a solitary, non-tender, soft-to-firm, pedunculated red scalp mass with a smooth surface, measuring 2 x 2 x 3 cm, was found over the left occipital area, with mild tenderness on touching. Excision was performed and sent for histopathological examination, which showed an adnexal tumor with features consistent with nodular hidradenomas, such as the tumor involving deep and peripheral margins. In a focal area, the mitotic rate was up to 3/10 HPF (high-power field) and was associated with a focal area of necrosis, which are considered atypical features. The differential diagnosis includes hidradenocarcinoma, renal cell carcinoma, basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, trichoblastoma, trichilemmoma, cystadenoma, syringoma, and sebaceous adenoma.