Which physical findings are characteristic of classic porokeratosis of Mibelli (PM)?

Updated: Oct 09, 2020
  • Author: Amarateedha Prak LeCourt, MD; Chief Editor: William D James, MD  more...
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Answer

The lesion develops as a small, light brown, keratotic papule that slowly expands to form an irregularly shaped, annular plaque with a raised, ridgelike border. This border may be hypertrophic or verrucous and may be greater than 1 mm in height. A thin furrow is typically seen in the center of the ridge, causing a Great Wall of China effect. The lesion is slightly hypopigmented or hyperpigmented, minimally scaly, slightly atrophic, hairless, and anhidrotic. The size may vary from a few millimeters to several centimeters.

Lesions may be found anywhere, including the mucous membranes, although they most commonly occur on the extremities. Generally, few lesions are observed. Porokeratosis ptychotropica is a verrucous variant that is localized to the buttocks and clinically resembles psoriasis. Note the image below.

Porokeratosis of Mibelli on the lower leg in a ren Porokeratosis of Mibelli on the lower leg in a renal transplant recipient.

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