Dermatitis exfoliativa is an inflammatory disease of an acute type, characterized by a more or less general erythematous inflammation, in exceptional instances vesicular or bullous, with epidermic desquamation or exfoliation accompanying or following its development. Constitutional disturbance, which may be of a serious character, is sometimes present. It is a rare and obscure affection, running its course usually in several weeks or months, but exhibiting a decided tendency to relapse and recurrence. In many cases it is persistently chronic, with exacerbations and remissions. In some instances it develops from a long-continued and more or less generalized eczema or psoriasis, and in exceptional cases it is started by the careless use of mercurial ointment and of chrysarobin ointment. [Illustration: Fig. 19. Dermatitis Exfoliativa.] In another type of the disease, formerly described as _pityriasis rubra_, the skin is pale red or violaceous-red, but is rarely thickened, continued exfoliation in the form of thin plates taking place. Its course is variable, lasting for years, with remissions. An exfoliating generalized dermatitis is exceptionally observed in the first weeks of life (_dermatitis exfoliativa neonatorum_), lasting some weeks, and in most cases followed by recovery. There are no special constitutional symptoms, the fatal cases usually dying of marasmus. As will be seen dermatitis exfoliativa varies considerably in degree; it may be extremely mild, resembling in appearance the scarlet-fever eruption (erythema scarlatiniforme) and running a rapid course; or the skin-condition and the systemic symptoms may be of grave and persistent character. #Give the treatment of dermatitis exfoliativa.# General treatment is based upon indications, and externally soothing applications, such as are employed in acute and subacute eczema, are to be used. #Lichen Planus.# #What is lichen planus?# Lichen planus is an inflammatory disease characterized by small, flat and angular, smooth and shining, or scaly, discrete or confluent, red or violaceous-red papules, having a distinctly papular or papulo-squamous course, and attended with more or less itching. #Describe the symptoms of lichen planus.#