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Rare Cases of Perianal and Perineal Keratoacanthomas Reported

By: Sarah Campen, PharmD
Posted: Wednesday, October 30, 2019

Reported in the Journal of Cutaneous Pathology were two cases of keratoacanthoma in rare anatomic locations, including reportedly the first case of perineal keratoacanthoma and the tenth case of perianal keratoacanthoma reported in the literature to date. Both lesions showed a histopathologic resemblance to subungual keratoacanthoma, a nonfollicular keratoacanthoma with distinctive morphologic features.

“Keratoacanthoma remains an important diagnostic entity, particularly in uncommon sites, and must be distinguished from traditional squamous cell carcinoma to ensure correct treatment,” explained Nathan Paulson, MD, of the Yale School of Medicine in New Haven, Connecticut, and colleagues.

The first case involved a 68-year-old woman who presented with a 0.6-cm nodule of the perineum that grew rapidly over several weeks, with a clinical presentation that suggested squamous cell carcinoma or a wart. Histologic examination of the excisional biopsy revealed an acanthotic, hyperkeratotic keratinocytic proliferation, and numerous dyskeratotic keratinocytes were observed.

The second patient was a 68-year-old man who presented with a 3.5-cm perianal nodule that grew rapidly over several weeks, leading to discomfort and bleeding. Although the clinical impression indicated condyloma acuminatum, histology showed an exoendophytic, flask-like appearance of well-differentiated, keratinizing squamous epithelium with a central keratin plug. Excision of the specimen revealed a crateriform lesion.

Over 11 years and 10 months of follow-up, respectively, there has been no evidence of recurrence or metastasis in either patient. “Recognition of resemblance to subungual keratoacanthoma may prove helpful in the diagnosis of perianal and perineal keratoacanthomas,” concluded the authors.

Disclosure: The study authors reported no conflicts of interest.

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