Abstract

Subcutaneous granuloma annulare (SGA) is a rare, benign noninfectious histiocytic disease of unknown cause, characterized by necrobiosis of the connective tissue surrounded by infiltrates of histiocytes and lymphocytes. We report a case of SGA in a 49/12-year-old boy. The lesions were five nontender subcutaneous nodules in the parieto-occipital scalp, measuring 1.0 cm to 2.0 cm in diameter. Microscopical examination revealed variable stages of multiple necrobiotic areas, which showed central necrobiosis with palisading histiocytes, involving both the lower dermis and subcutaneous fatty tissue. Electron microscopic findings revealed many histiocytes in the necrobiotic areas with degenerating and necrotic collagen fibers as well as regenerating fibroblasts.

• Keywords: Granuloma annulare;Scalp;Necrobiosis;