piedra

A fungus disease of the hair characterized by the formation of numerous waxy, small, firm, nodular masses on the hair shaft. SEE ALSO: trichosporosis. [Sp. a stone]

- black p. p. involving the hairs of the scalp, caused by Piedraia hortae and characterized by firmly adherent black, hard, gritty nodules composed of an organized, firmly cemented mass of fungus cells; the fungal growth is always located above the level of the hair follicles; the disease occurs in humid tropical areas of the Americas, Africa, and Asia, and attacks chimpanzees and other primates as well as humans.

- p. nostras a condition similar to p., but affecting the hair of the beard.

- white p. p. of the beard, moustache, and genital areas, as well as the scalp, caused by Trichosporon beigelii and found in South America, Europe, and Japan; characterized by soft, mucilaginous, white to light brown nodules, within as well as on the hairs.

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pie·dra pē-'ā-drə n a fungus disease of the hair marked by the formation of small stony nodules along the hair shafts

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n.

a fungal disease of the hair in which the hair shafts carry hard masses of black or white fungus. The black fungus, Piedraia hortae, is found mainly in the tropics and the white varieties, Trichosporon species, in temperate regions.

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pie·dra (pyaґdrə) [Sp. “rock”] a fungal infection of the hair shaft characterized by the presence of dark or pale, firm, irregular nodules composed of fungal elements.