lichen (redirected from lichenous)

lichen /li·chen/ (lik´'n)

1. any of certain plants formed by the mutualistic combination of an alga and a fungus.

2. any of various papular skin diseases in which the lesions are typically small, firm papules set close together.

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lichen amyloido´sus  a condition characterized by localized cutaneous amyloidosis.

lichen fibromucinoido´sus , lichen myxedemato´sus a condition resembling myxedema but unassociated with hypothyroidism, marked by a fibrocystic proliferation, increased deposition of acid mucopolysaccharides in the skin, and the presence of a circulating paraprotein; it may present as lichenoid papules or urticaria-like plaques and nodules.

lichen ni´tidus  a chronic inflammatory eruption consisting of many, pinhead-sized pale, flat, sharply marginated, glistening, discrete papules, scarcely raised above the skin level.

lichen planopila´ris  a variant of lichen planus characterized by formation of acuminate horny papules around the hair follicles, in addition to the typical lesions of ordinary lichen planus.

lichen pla´nus  an inflammatory skin disease with wide, flat, violaceous, shiny papules in circumscribed patches; it may involve the hair follicles, nails, and buccal mucosa.

lichen ru´ber monilifor´mis  a variant of lichen simplex chronicus with papules arranged in linear beaded bands.

lichen ru´ber pla´nus  l. planus.

lichen sclero´sus  a chronic atrophic skin disease marked by white papules with an erythematous halo and keratotic plugging, usually around the external genitalia or in the perianal region.

lichen scrofuloso´rum , lichen scrofulo´sus any eruption of minute reddish lichenoid follicular papules in children and young adults with tuberculosis.

lichen sim´plex chro´nicus  a dermatosis of psychogenic origin, marked by a pruritic discrete or, more often, confluent papular eruption, usually confined to a localized area.

lichen spinulo´sus  a condition in which there is a horn or spine in the center of each hair follicle.

lichen stria´tus  a self-limited condition characterized by a linear lichenoid eruption, usually in children.

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li·chen (lkn)

n.

Any of various skin diseases characterized by patchy eruptions of small, firm papules.

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lichen

1. any of certain plants formed by the mutualistic combination of an alga and a fungus.

2. any of various papular skin diseases in which the lesions are typically small, firm papules set very close together, the specific kind being indicated by a modifying term.

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lichen tropicus

see equine allergic dermatitis.