Malignant Transformation of Nodular Hidradenoma in the Lower Leg

Abstract

Nodular hidradenoma (NH) is a benign adnexal tumor that arises from either eccrine or apocrine sweat glands. NH can originate from any cutaneous site, but the most common sites are the head and anterior surface of the trunk, with very rare cases in the extremities. Long-standing NH has been reported to undergo malignant transformation to malignant NH (MNH); however, its occurrence in the lower leg is extremely rare with only one other case reported to date. In this report, we present a rare case of MNH occurring in the lower leg which was resected with the intent to make a diagnosis. At the final follow-up after 11 months, no local recurrence or metastasis has been observed.

Pedunculated Tumor on the Posterior Neck

“…Nodular hidradenoma (also known as acrospiroma, solid-cystic hidradenoma, clear cell hidradenoma, and eccrine sweat gland adenoma) is a benign adnexal tumor of the apocrine or eccrine glands. 1,2 Nodular hidradenoma can arise at any cutaneous site but most commonly arises on the head and anterior portion of the trunk and rarely on the extremities. 2 It presents as a solitary nodular, cystic, or pedunculated mass that can reach up to several centimeters in diameter.…”

“…1,2 Nodular hidradenoma can arise at any cutaneous site but most commonly arises on the head and anterior portion of the trunk and rarely on the extremities. 2 It presents as a solitary nodular, cystic, or pedunculated mass that can reach up to several centimeters in diameter. 2,3 Nodular hidradenoma more commonly affects women compared to men with a ratio of 1.7 to 1 and commonly presents between the third and fifth decades of life, with an average age at presentation of 37.2 years.…”

“…2 It presents as a solitary nodular, cystic, or pedunculated mass that can reach up to several centimeters in diameter. 2,3 Nodular hidradenoma more commonly affects women compared to men with a ratio of 1.7 to 1 and commonly presents between the third and fifth decades of life, with an average age at presentation of 37.2 years. 2,4 There can be associated skin changes, including smoothening, thickening, ulceration, and bluish discoloration.…”

“…2,3 Nodular hidradenoma more commonly affects women compared to men with a ratio of 1.7 to 1 and commonly presents between the third and fifth decades of life, with an average age at presentation of 37.2 years. 2,4 There can be associated skin changes, including smoothening, thickening, ulceration, and bluish discoloration. Dermoscopy commonly shows a pinkish homogenous area that extends throughout the entire lesion.…”

“…5 Rapid increase in tumor size can be indicative of malignant transformation, hemorrhage into the tumor, or trauma to the area. 2 Histologically, nodular hidradenoma consists of a circumscribed, nonencapsulated, multilobular tumor commonly found in the dermis and sometimes extending into the subcutaneous tissue. There usually is no epidermal attachment, and the overlying epidermis largely is normal.…”