August 2018 | Case of the Month

The diagnosis is consistent with porokeratosis. 

The term porokeratosis refers to skin lesions with a thinned centre surrounded by a ridge-like border called the cornoid lamella. There are different types of porokeratosis.

Clinically the lesions have the following features:

• Lesions are annular with a well-demarcated, slightly raised keratotic rim known as a cornoid lamella. The centre may be scaly or thin and atrophic
• They grow gradually to between 3-10 mm. Grouped lesions will appear larger. Rarely, lesions of porokeratosis of Mibelli can be very large and are termed ‘giant’
• Dermoscopically there are parallel lines, sometimes referred to as 'tram lines' at the periphery

The condition is essentially harmless, although there is no effective treatment.

Please refer to the chapter on porokeratoses to read more about the condition and the different types.