Porokeratosis and Cutaneous Malignancy

BACKGROUND: Porokeratosis is a disorder of epidermal keratinization manifested clinically by a raised border and histologically by a cornoid lamella. While cutaneous malignancy has been reported to arise in porokeratosis, the risk remains unknown. In the past it has been associated with a history of radiation therapy. OBJECTIVE: The purpose of this study is to estimate the frequency of cutaneous malignancy arising in porokeratosis and define those patients who are at highest risk. METHODS: All cases in the English language literature in the last 30 years were reviewed. RESULTS: Twenty-one (7.5%) of 281 cases reported revealed a malignancy arising within porokeratosis. Large lesions, those of long-standing duration, and the linear type were at greatest risk. Radiation therapy was an infrequently identified risk factor. CONCLUSION: Porokeratosis is a premalignant condition, with certain groups of patients at greatest risk for malignant transformation.