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Correspondence |

Clinical and Dermoscopic Features of Porokeratosis of Mibelli

Maria A. Pizzichetta, MD; Vincenzo Canzonieri, MD; Cesare Massone, MD; H. Peter Soyer, MD
Arch Dermatol. 2009;145(1):91-92. doi:10.1001/archderm.145.1.91.
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Porokeratosis is a rare, genetically determined disorder of epidermal keratinization characterized by lesions with keratotic borders corresponding histopathologically to compact columns of parakeratotic cells called cornoid lamellae that extend through the stratum corneum.1 The clinical variants include porokeratosis of Mibelli (PM), disseminated superficial actinic porokeratosis, linear porokeratosis, porokeratosis palmaris, plantaris et disseminate, and punctate porokeratosis.1

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Figure 1.

Clinical image revealing a whitish-red plaque on the right forearm of a 15-year-old boy. The affected area is made up of numerous whitish-red round papules that coalesce into irregular plaque and single papules, the area perimeter defined by a whitish border and cleaved by a central furrow. Slightly raised whitish-red portions can also be observed (original magnification ×20).

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Figure 2.

Dermoscopic images of the affected area exhibiting a cluster of lesions coalescing into plaque on the right forearm of a 15-year-old boy (original magnifcation of the main photograph ×10; inset, ×20). A thin whitish rim surrounds the entire perimeter of the affected area (black arrows), and brown close dots join to form a continuous line present inside the whitish rim (blue arrows). In the central portion of the lesions, a diffuse, whitish-brown pigmentation, globules, and dots (green arrows), red dots (arrowheads), and red lines (white arrows) (enlarged in the inset) can be recognized.

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Figure 3.

Histopathologic images under hematoxylin-eosin (A) and gram (B) stains (original magnification ×250 for both panels). The cornoid lamella (bright blue under gram stain) is characterized by a column of parakeratosis with a normal orthokeratotic epidermal stratum corneum above a thin granular layer. A few vacuolated and dyskeratotic cells are evident in the spinous layer.

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