Porokeratosis is an uncommon tumor which occurs in two forms. Disseminated superficial actinic porokeratosis is seen most often. It consists of extensive flat, slightly scaling discrete lesions. They may be solitary or literally hundreds of lesions primarily located on the light exposed areas of the arms and legs. Adult patients who have a fair complexion are the norm. Each of the individual lesions are surrounded by a thickened wall of kurtosis which identify the diagnostic hallmark. These lesions may develop into squamous cell carcinomas.
Porokeratosis of Mibelli is rarely seen but quite characteristic clinically. It presents with a plaque normally enlarging centrically with atrophy or thinning in the center and an elevated, warty border around the entire lesion often referred to as the great wall of china. Less commonly, porokeratosis type lesions can occur as a solitary lesion on the palms and soles or in a linear pattern. Therapy for extensive lesions can be frustrating.