Lupus-like reaction to interferon at the injection site: report of five cases

Background: Interferon therapy at the injection sites has been related to different cutaneous lesions including erythema and induration as the most frequent ones. While the glycoprotein induces fatigue, fever and is even believed to precipitate autoimmune disorders such as type I diabetes, thyroid disease and systemic lupus erythematosus, a lupus erythematosus-like histologic reaction at the interferon injection site has never been reported. To our knowledge, a microscopic self-resolving lesion mimicking lupus erythematosus at the injection site of interferon has not been described. Results:We report five cases of cutaneous lesions at the inoculation site of interferon with a histopathologic lupus erythematosus-like pattern. Three of them were receiving interferon alfa therapy because of a malignant melanoma and the other two patients were receiving interferon beta-1b for multiple sclerosis. Biopsy specimens taken from different lesions showed similar microscopic findings consisting of dermal mucin deposits and dense lymphocytic infiltrates along hair follicles with hydropic degeneration of follicular basal layer. Conclusions: Multiple cutaneous lesions related to interferon at the injection site have been reported, but none of them with a histologic lupus-like presentation. In this study we describe five cases in which interferon therapy has induced a resolutive cutaneous lesion mimicking lupus erythematous. This peculiar microscopic pattern has been previously described once before, but interpreted as cutaneous mucinosis.