A 66-year-old man is referred for evaluation of a lesion on his abdomen. He first noticed the growth approximately 1 year ago, and it has remained asymptomatic. The patient’s medical history shows hypertension and cigarette smoking for a long duration. Examination reveals a 1.5cm well-demarcated, hyperpigmented nodule with a smooth surface. Multiple nevi are noted elsewhere. Inguinal lymph nodes are nonpalpable.
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Hidradenomas are benign tumors of either the apocrine or eccrine sweat glands. Three types have been described: clear cell hidradenoma, nodular hidradenoma, and solid-cystic hidradenoma; diagnosis is based on histology.
Clear cell hidradenoma peak incidence is in patients aged ≥60 years. Clinically, the nodules range in size from 0.5cm to 3.0cm and range in color from flesh-toned to red-brown or blue; lesions often become ulcerated.1
Nodular hidradenoma presents as a solitary, firm, pigmented nodule that may exceed 1cm in diameter.2,3 Lesions may increase in size but do so gradually. Although rare, nodular hidradenomas can undergo malignant transformation; therefore, clinicians may recommend either periodic observation or full excision.3
Solid-cystic hidradenoma is most commonly found on the head, trunk, and upper extremities in patients aged ≥50 years. Lesions appear as isolated, flesh-colored to hyperpigmented nodules that have a smooth surface.4 Ulceration accompanied by serous drainage may occur in approximately 15% of cases.5
Histology reveals cystic structures intermixed with slightly basophilic cytoplasm and round nuclei. Wide surgical excision is recommended to prevent recurrence.5
Stephen Schleicher, MD, is director of the DermDox Center for Dermatology in Pennsylvania, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College.
1. Egesi A, Ingraffea A. What is your diagnosis? Clear cell hidradenoma. Cutis. 2014;94(6):268, 271-272.
2. Hernández-Pérez E, Cestoni-Parducci R. Nodular hidradenoma and hidradenocarcinoma. A 10-year review. J Am Acad Dermatol. 1985;12(1 Pt 1):15-20.
3. Ngo N, Susa M, Nakagawa T, et al. Malignant transformation of nodular hidradenoma in the lower leg. Case Rep Oncol. 2018;11(2):298-304.
4. Winkelmann R, Wolff K. Solid-cystic hidradenoma of the skin: clinical and histopathologic study. Arch Dermatol. 1968;97(6):651-661.
5. Li Z-Y, Chang J-M. Solid-cystic hidradenoma. Int J Dermatol. 2019;2(3):191-192.