Its common site is the face, usually the nose and cheeks, with a tendency toward symmetry; it is often limited to these parts, but may occasionally be seen upon other regions, more especially the lips, ears, and scalp. In rare instances a great part of the general surface may become involved. #Describe the symptoms of lupus erythematosus.# Usually the disease begins as one or several rounded, circumscribed, pin-head- to pea-sized lesions; slightly scaly, somewhat elevated, and of a pinkish, reddish or violaceous color. They slowly, or somewhat rapidly, increase in area, and after attaining variable size remain stationary; or they may progress and coalesce, and in this manner sooner or later involve considerable surface. The patches are sharply defined against the sound skin by an elevated border, while the central portion is somewhat depressed and usually atrophic. More or less thickening and infiltration are observed. _There is no tendency to ulceration_. The scaliness is, as a rule, scanty. The gland-ducts are enlarged, patulous or plugged with sebaceous and epithelial matter. The subjective symptoms of burning and itching are usually slight and often wanting. #What course does lupus erythematosus pursue?# As a rule, the disease is persistent, although somewhat variable. At times the patches retrogress, involution taking place with or without slight sieve-like atrophy or scarring. #State the causes of lupus erythematosus.# The etiology is obscure. Some observers believe it to be a variety of cutaneous tuberculosis. It is essentially a disease of adult and middle age; is more common in women, and more frequent in those having a tendency to disorders of the sebaceous glands. It may, in fact, begin as a seborrh[oe]a. #What is the pathology?# It was formerly considered a new growth, but recent opinion tends toward regarding it as a chronic inflammation of the cutis, superinducing degenerative and atrophic changes. Variable [oe]dema of the prickle layer and of the cutis is found. There is no tendency to pus formation. [Illustration: Fig. 42. Lupus Erythematosus.] #Is there any difficulty in the diagnosis of lupus erythematosus?# As a rule, not, as the features of the disease--the sharply circumscribed outline, the reddish or violaceous color, the elevated border, the tendency to central depression and atrophy, the plugged up or patulous sebaceous ducts, the adherent grayish or yellowish scales, together with the region attacked (usually the nose and cheeks)--are characteristic. #State the prognosis of lupus erythematosus.#