The "butterfly" rash over the nose and cheeks in lupus erythematosus (LE) is probably the best-known example of a cutaneous lesion heralding a systemic disease. This sign is so well established in every physician's mind that (1) the butterfly eruptions of seborrheic dermatitis, rosacea, or erysipelas are commonly misdiagnosed as LE lesions, and (2) LE lesions which occur in other distribution patterns may go unrecognized.
The biopsy specimen from a lesion in question will usually differentiate lupus erythematosus from other cutaneous disorders. The clinician, however, can at times make a presumptive diagnosis if he looks closely at the distinctive morphologic appearance of the lesion.
Lupus erythematosus often has no cutaneous expression. Skin lesions also may be nonspecific in character, but, frequently, features which accurately identify the disease can be recognized. Specific lesions are characterized by an adherent dry scale with evidence of follicular plugging, by a dusky erythema, and by