Skin, Granuloma annulare

Granuloma annulare is a granulomatous skin disease that occurs most frequently on the dorsum of the hands and arms. Clinically, the lesions appear as reddish papules in annular arrangements of 1-5 cm in diameter. Granulmoa annulare may be seen in its generalized form, and it may be associated with diabetes mellitus or HIV infection.

Key histological features are the necrobiotic collagen or palisading granuloma, with lymphocytes and histiocytes palisading around a hypocellular dermis. Other causes of non-infectious palisading granulomatous dermatitis include necrobiosis lipoidica, rheumatoid nodule and sarcoidosis.