Abstract

A 38-year-old Hispanic female presented to the dermatology clinic with cystic lesion on her left lateral thigh measuring about 9 x 4 mm, which was present since age 12. She also reported occasional episodes of bleeding. Recently she noticed a change in color and the lesion was then biopsied. On histopathological examination, a well-circumscribed dermal based tumor, without epidermal connection, was identified. It had arborizing glandular architecture with papillary foldings projecting into cystic spaces. It was comprised of basaloid cells with a two layered epithelium consisting of an outer layer of small round to cuboidal shaped myoepithelial cells and inner layer of columnar apocrine secretory cells. This outer layered myoepithelial cell layer was highlighted by P63 stain as well. Rare scattered mitoses were also identified. Overall, these histopathologic findings were diagnostic for hidradenoma papilliferum. Only 21 cases have been reported on an anatomical location outside the anogenital region. Hidradenoma papilliferum has been postulated to arise from mammary glands. This rare presentation is the third case of hidradenoma papilliferum affecting the thigh and the first ever case reported in an Hispanic woman.

Financial Disclosure:
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