Friday, 29 August 2008
A 63-year-old woman consulted for this brown-red annular plaque on her right leg. This lesion had been slowly expanding for 2 years. The lesion was slightly hypopigmented in its center. Palpation at the periphery revealed a raised annular border.
The clinical examination was in favor of a porokeratosis (Mibelli)
This diagnosis of porokeratosis was easily confirmed with dermoscopy.
The dermoscopic aspect of porokeratosis is a "white track" structure with a brown pigmentation visible in the inside of the track.
This white tract structure corresponds to the cornoid lamella.
In the central part of the lesion, dermoscopy may feature a white area, red dots, globules and lines corresponding to vessels.
Reference: P.Zaballo, S. Puig, J. Malvehy. Dermoscopy of disseminated superficial actinic porokeratosis. Arch Dermatol 2004; 140: 1410