Piedra is a

hair disease Hair diseases are disorders primarily associated with the follicles of the hair. A few examples are: * Bubble hair deformity * Hair casts (shedding of remnants of the inner root sheath) * Hair loss (alopecia) * Hirsutism (excessive hair on body p ...

caused by a

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

, which causes formation of nodules on the hair shaft.Veasey JV, Avila RB, Miguel BAF, Muramatu LH. White piedra, black piedra, tinea versicolor, and tinea nigra: contribution to the diagnosis of superficial mycosis. ''An Bras Dermatol''. 2017 May-Jun;92(3):413-416. Types include: *

White piedra White piedra (or tinea blanca) is a mycosis of the hair caused by several species of fungi in the genus ''Trichosporon''. It is characterized by soft nodules composed of yeast, yeast cells and arthroconidia that encompass hair shafts. Diagnosis W ...

Black piedra ''Piedraia hortae'' is a superficial fungus that exists in the soils of tropical and subtropical environments and affects both sexes of all ages. The fungus grows very slowly, forming dark hyphae, which contain chlamydoconidia cells and black co ...

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{{Mycoses Mycosis-related cutaneous conditions Animal fungal diseases Human hair