Open comedones overlying granuloma annulare in a photoexposed area

A 57-year-old, fair-skinned female patient with lesions of granuloma annulare located on her forearms - with signs of actinic damage - is described. No response was observed after successive treatments with topical corticosteroids and oral pentoxifylline. Four years later, the patient developed open comedones on the rim of granuloma annulare lesions. The loss of elastic fibers seen in both granuloma annulare and solar elastosis is presumed to have induced the appearance of open comedones, because of a loss of supporting properties of the dermis inducing a distension of the infundibular canal of the sebaceous follicle, as seen in the Favre-Racouchot disease and actinic comedonal plaque. Concomitantly, the patient developed insulin-dependent diabetes mellitus. Treatment with insulin resulted in the disappearance of open comedones and notably regression of lesions of granuloma annulare. Response to insulin therapy in our case supports the hypothesis that insulinopenia could participate in the development of granuloma annulare in some cases.