(Synonyms: Lichen Ruber; Lichen Ruber Acuminatus.)

Describe pityriasis rubra pilaris.

Pityriasis rubra pilaris is an extremely rare disease, usually of a mildly inflammatory nature, characterized by grayish, pale-red or reddish-brown follicular papules with somewhat hard or horny centres; discrete and confluent, and covering a part or the entire surface. The skin is harsh, dry and rough, feeling to the touch somewhat like the surface of a nutmeg-grater or a coarse file. More or less scaliness is usually present in the confluent patches and on the palms and soles; in these latter regions the papules are rarely seen. The duration of the disease is variable, and relapses are common. It bears resemblance at times to keratosis pilaris, ichthyosis, dermatitis exfoliativa; it is considered identical with the lichen ruber acuminatus of Kaposi, and by many also with the lichen ruber of Hebra. The etiology is obscure.

Treatment, both constitutional and local, is to be based upon general principles; stimulating applications, with frequent baths, such as are advised in psoriasis, are the most satisfactory. It is rebellious, and not much more than palliation can be effected in some cases, in others the outlook is more hopeful.