Pityriasis

(pit-ir-i'-as-is). A term formerly applied to various pathologically di ociated skin-affections, the most striking clinical feature of which is the presence of fine, branny desquamation. Also a synonym of Seborrhea. P. cachecticorum. Same as Seborrhea. P. capillitii, P. capitis. See Alopecia furfur ace a. P. circinata et margin at a, an eruption of rose-colored spots on the trunk, the limbs, and in the axillse. It is of parasitic origin. P. gravid arum; Chloasma gravid arum; the discoloration of the skin sometimes observed during pregnancy. P. in fan til is, a desquamative eruption attacking infants; it is probably eczema. P. maculata et circinata. See P. rose a. P. nigra, pityriasis with pigmentation occurring in the aged. Also, a papular eruption tenninating in slight desquamation, which attacks children brought to England from India. P. nigricans. Synonym of Chromidrosis. P. pilar is. See Keratosis pilar is. P. rose a; P. maculata et circinata; Herpes tonsurans maculosus; an acute inflammatory skin-disease characterized by macular or circinate lesions, occurring mostly on the trunk. The eruption consists at first of rosy-red spots, which later become brownish. The lesions are round, but owing to their tendency to recover at the center and to extend peripherally, gyrate and irregular figures are formed. Furfuraceous desquamation is a marked feature. P. rubra; Dermatitis exfoliativa; a chronic inflammatory skin-disease, beginning in one or more localized patches, which coalesce and gradually invade the whole body. The skin may be of a dark or vivid red or bluish-red. There is no infiltration and no moisture, but there may be edema of the lower limbs. The desquamation is very free; the scales are thin and papery on the general surface, imbricated, and from a line to an inch or more in diameter. The disease lasts months or years, and generally ends fatally from progre ive emaciation and exhaustion, or from some intercurrent affection. P. rubra pilar is; Lichen ruber a cum in at us; a primarily non-inflammatory disease of the skin, characterized by follicular papules, with horny centers, tending to become general or even universal in distribution. The papules are hard, dry, brownish-red, and seated at the hair-follicles. An atrophied hair occupies the center, and is surrounded by a sort of horny sheath which penetrates into the follicle. The papules vary in size from a small pin's head to a millet-seed, and are most abundant on the limbs.