White piedra is a superficial cosmetic fungal infection of the hair shaft caused by Trichosporon beigelii. Infected hairs develop soft greyish-white nodules along the shaft. Essentially no pathological changes are elicited. White piedra is found worldwide, but is most common in tropical or subtropical regions.
Infections are usually localised to the axilla or scalp but may also be seen on facial hairs and sometimes pubic hair. White piedra is common in young adults. The presence of irregular, soft, white or light brown nodules, 1.0-1.5 mm in length, firmly adhering to the hairs is characteristic of white piedra.
1. Clinical Material: Epilated hairs with white soft nodules present on the shaft.
2. Direct Microscopy: Hairs should be examined using 10% KOH and Parker ink or calcofluor white mounts. Look for irregular, soft, white or light brown nodules, 1.0-1.5 mm in length, firmly adhering to the hairs.
3. Culture: Hair fragments should be implanted onto primary isolation media, like Sabouraud's dextrose agar. Colonies of Trichosporon beigelii are white or yellowish to deep cream colored, smooth, wrinkled, velvety, dull colonies with a mycelial fringe.
4. Serology: Not required for diagnosis.
5. Identification: Characteristic clinical, microscopic and culture features.
Shaving the hairs is the simplest method of treatment. Topical application of an imidazole agent may be used to prevent reinfection.
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