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| Fig. 22.9 Dermatomyositis. A, Characteristic violaceous erythema over dorsal knuckles in a patient with associated breast cancer. B, Characteristic photodistributed erythema with heliotrope of upper eyelids. (Courtesy of James E. Fitzpatrick, MD.) |
Two cutaneous findings have been described as pathognomonic of dermatomyositis: Gottron’s papules and Gottron’s sign. Gottron’s papules are erythematous to purplish flat papules on the extensor surfaces of the interphalangeal joints. Gottron’s sign consists of symmetrical violaceous erythema, sometimes with edema, over the dorsal knuckles of the hands, elbows, knees, and medial ankles (Fig. 22-9A). Other skin findings that are characteristic of dermatomyositis are periorbital edema with a lilac-colored erythema (heliotrope, Fig. 22-9B), periungual telangiectasia with cuticle dystrophy, and a photodistributed violaceous erythema of the forehead; also, sun-exposed areas of the neck, upper chest, shoulders, dorsal arms, forearms, and hands. A diagnostic clue favoring dermatomyositis over lupus erythematosus is the violaceous erythema or papules over the knuckles. Lupus, on the other hand, shows erythema over the dorsal phalanges, but often spares the knuckles.
Callen JP, Wortmann RL: Dermatomyositis,
Clin Dermatol 24:363–373, 2006.
