Granuloma annulare (GA) is a benign inflammatory skin disease¹. Here, we report an atypical clinical presentation of localized GA associated with cysts and open comedones.

An 85-year-old woman presented with a one-month history of asymptomatic plaque on her right forearm. She had diabetes mellitus, hypertension and dyslipidemia. Physical examination identified erythematous well-demarcated and extensive plaque covered with multiple yellowish papules from which a creamy liquid was easily expressed (figure 1A). We noted, also, multiple open comedones located exclusively on the plaque, filled with black keratotic plugs and associated with cribriform scarring.

Histopathological examination of skin biopsy showed an area of necrobiosis surrounded by histiocytes and lymphocytes in the mid dermis, with some multinucleated giant cells (figure 1B and 1C). The diagnosis of GA associated with cyst and open comedones was made.

GA is a benign dermatosis with variable clinical presentations. Some triggering conditions were reported, especially, trauma, vaccination, infections and sun exposure¹. Localized GA is the most commonly recognized presentation and lesions are usually concentrated on the extremities. The finding of milia, cysts and open comedones over the lesions of GA is extremely rare, with only three previous reports in the literature². Cysts and open comedones, which are formed by dilated pilosebaceous follicles filled with laminated keratinous material, may be explained by collagen and elastic fibrer damage observed in actinic GA².