Porokeratosis and immunosuppression.

Immunosuppression may favour the development of disseminated superficial porokeratosis (DSP). We report the clinical features and the outcome of DSP in 24 patients receiving immunosuppressive treatment (group A), and compare the characteristics of the disease with those of 13 immunocompetent patients with DSP (group B). The two groups were similar with regard to age, sex, area of skin involvement and mean follow-up. There was a family history of DSP in only two patients in group A, compared with five patients in group B (P = 0.03). The skin type, based on the tanning response to sunlight, was not significantly different between the two groups. Two of the 24 patients in group A had high sun exposure, compared with five of the 13 patients in group B (P = 0.03). Moreover, 10 patients in group A and 11 in group B (P = 0.01) exhibited worsening of the disease after exposure to sunlight, usually during the summertime. These observations appear to support the hypothesis that sun exposure is not always essential for the development of porokeratosis in immunosuppressed patients. None of our patients developed skin cancer in porokeratotic lesions during the follow-up period.