lichen

(li'ken) [G. leichen, a tetter-like eruption.] I A cryptogamic mo -like plant, forming patches on rocks, tree-trunks, etc.; thought to be algse with parasitic fungi. (The word in this sense is sometimes pronounced lich'en.) 2. general term denoting any papidar eruption of the skin, now noting usually plan us. acumina'tus, a form with acuminate papular lesions, 1. ruber. 1. a'grius, acute papular eczema of severe type. 1. marked by the occurrence of annular lesions, ^i aspects of the fingers. 1. annul a'tus, 1. circinatus. 1. circina'tus, seborrheic dermatitis with annular lesions. 1. haemorrhag'icus, a papular eruption due to hemorrhage into the hair-follicles. 1. infan'tum, strophulus. 1. i'ris, ringworm with concentric rings of erythematous papules. 1. liv'idus, 1. scrofulosus with extravasation of blood into the papules, purpura papillosa. 1. obtu's us, a form in which the papules are large and roimded instead of flattened. 1. pila'ris, keratosis pilar is. 1. pla'nus, an eruption of flattened papules, of a reddish color and shining surface, occurring singly or grouped in patches of varying size and shape; the eruption occurs chiefly on the flexor surfaces of the extremities; but may involve the trunk or the mucous membranes. 1. pla'nus annul a'ris, a form in which the papules are grouped in ring figures. 1. pla'nus hypertroph'icus, obtusus. pla'nus verruco's us, a form in which the papules coalesce, forming wart-like patches 1. psori'as is, (i) pityriasis rubra pilar is; (2) 1. plan us. 1. ru'ber, 1. ru'ber acumina'tus, pitjrriasis rubra pilar is. 1. ru'ber monilifor'mis, an eruption of obtuse papules arranged along raised lines on the extremities, following the general direction of their axes. I. ru'ber pla'nus, 1. plan us. 1. scrofulo's us, 1. scrofuloso'rum, an eruption of reddish papules, single or aggregated in patches of varying size, occurring in scrofulous subjects. 1. sim'- plez, papular eczema. 1. spinulo's us, a particularly rough form of 1. pilar is. 1. strophulo's us, miliaria rubra. 1. syphilit'icus, follicular syphilide. 1. trop'icus, miliaria rubra. 1. urtica'tus, chronic urticaria. 1. variega'tus, maculopapular erythroderaiia.