Which physical findings are characteristic of the less common variants of porokeratosis?

Updated: Oct 09, 2020
  • Author: Amarateedha Prak LeCourt, MD; Chief Editor: William D James, MD  more...
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Porokeratosis ptychotropica presents with multiple plaques involving the medial buttocks and gluteal cleft, clinically resembling psoriasis.

Patients with porokeratotic adnexal ostial nevus develop hyperkeratotic papules and plaques, and occasionally punctate pits filled with a comedolike keratin plug. The lesions are typically on the extremities and occasionally the trunk and/or face. If present at birth, they may present as erosions that evolve into darker brown, well-marginated linear plaques. Pterygium formation can occur if lesions extend into the nail bed. Lesions are often distributed along the lines of Blaschko.

Rare case reports of porokeratotic adnexal ostial nevus (PAON) describe other findings, including psoriasis, focal anhidrosis, developmental delay, seizures, scoliosis, hemiparesis, polyneuropathy, hyperthyroidism, hearing loss, and breast hypoplasia. Squamous cell carcinoma has been reported to develop within well-established lesions. Additionally, late-onset lesions developing during adulthood may be clinically indistinguishable from PPPD. [68]

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