[Squamous cell carcinoma and disseminated superficial actinic porokeratosis].

Disseminated superficial actinic porokeratosis was first described by Chernosky and Anderson in 1969. It is characterized by multiple small keratotic lesions on sun-exposed areas beginning in the third of fourth decade. The development of a squamous cell carcinoma within lesions of porokeratosis or the association of superficial actinic porokeratosis with immunosuppression have been well documented. We report the case of a 68-year-old patient who presented actinic porokeratosis associated with rapidly evolutive squamous cell carcinoma of the leg. During the hospitalization, an IgA myeloma was discovered. The authors discuss the relationship between porokeratosis, immunosuppression, and squamous cell carcinoma. Pathogenesis of the lesions is interesting because it is admitted that a keratinocyte clone which carries the porokeratosis abnormality is going to proliferate because of immunosuppression, trauma and infectious diseases. It seems important to search for immunosuppression in patients presenting porokeratosis because the incidence of malignant transformation may increase.