Pityriasis rubra pilaris-like eruption following insulin therapy initiation.

Pityriasis rubra pilaris (PRP) is a chronic disorder of keratinization of unclear pathogenesis. PRP-like eruptions induced by drugs have rarely been described. A previously healthy 29-year-old man presented with a generalized, rapidly spreading, erythematosquamous dermatosis, that started three days after initiation of subcutaneous insulin therapy for diabetes mellitus type 1. Clinical and histopathological features were consistent with a PRP-like eruption, possibly due to insulin therapy. The patient was switched to insulin analogue therapy and a complete healing of all lesions was achieved after two months. No recurrence was seen after one year of follow-up. Other possible etiologies of PRP were excluded. The mechanism leading to the occurrence of drug-induced PRP-like eruptions are not clear. Since PRP may occur in the context of immunological anomalies, it is possible that diabetes mellitus type 1 may have been a predisposing condition for the development of PRP in this case.