Lichen

A skin disease characterized by elevation of the skin, serous discharge, scaling, and itching. Lichen is associated with wind, heat, and dampness. Lichen characterized by dryness and scaling of the skin is called dry lichen, whereas lichen that exudes a discharge is called damp lichen. Several specific forms exist. An itchy lichen around the nail that causes it to lose its luster and become deformed is ashen nail. Lichen of the foot characterized by itching and scaling of the skin between the toes is traditionally called foot damp qì in Chinese medicine; in China, it is now commonly known as Hong Kong foot, and in the West as athlete’s foot. Other forms of lichen include: coin lichen, characterized by clearly circumscribed red macules that often heal from the center; oxhide lichen, marked by thickening and hardening of the skin, like the skin on the neck of an ox; pine-bark lichen, a scaling lichen that looks like pine bark; suckling lichen, a papular lichen in infants affecting the head and face and capable of spreading to other parts of the body; yīn lichen is a lichen affecting the anterior and posterior yīn, i.e., the anus and genitals, and surrounding areas and attributed to wind-heat-damp invading the skin. Furthermore, purple and white patch wind, goose-foot wind, bald scalp sore, and fat sore are also classified in some modern sources as lichen.

Etymology

Chin 癣 xiǎn, is 藓 xiǎn, lichen, moss, with the grass signifier replaced with a sickness classifier to denote a pathological lichen on the body.

NB: Lichen is here not to be confused with same term as used Western medicine.