Interactive Quiz: Spontaneous Hair Loss
Answer: C. Trichosporon asahii
White piedra, or trichomycosis nodularis, is a common superficial fungal infection of the hair shaft caused by Trichosporon asahii, formerly known as Trichosporon beigelii.1,2 Trichosporon forms soft white to light brown nodules that are loosely adherent to the hair shaft. Cuticular invasion occurs within the nodules, weakening the shaft’s structural integrity and leading to breakage.
White piedra is normally found in the hair of the genitals, beard, moustache, eyebrows, eyelashes, axillae, and rarely the scalp.1-3 This is in contrast to black piedra, caused by Piedraia hortae, which is characterized by the presence of firmly attached, black/brown, hard nodules that are more commonly attached to scalp hair. White piedra is believed to be sporadic and prepathologic; Trichosporon is carried asymptomatically on the hair and skin of the patient.3,4
White piedra is more common in temperate and semitropical climates, including the Southern United States, and can be found in soil and vegetable matter or on body surfaces.4,5 People of all ages are affected, and age and sex incidence varies from country to country.2 The specific mode of transmission is not clear, and most suggest infection occurs from soil or animals; however, person-to-person transmission has been suggested as possible but rare.1-3,6
Patients with white piedra normally seek medical care because of hair loss, or they find visible nodules on their hair. The diagnosis of white piedra can be made purely by the visualization of the characteristic white to light brown soft nodules seen on the shafts of affected hairs.1,2,6
Microscopic examination of these nodules with 10% KOH preparation shows septate hyphae with arthroconidia. The hair shafts will have a positive pull test, breaking at the location of the nodules when tension is applied.1-3,5
Given that white piedra can be easily misdiagnosed, the differential diagnosis is important and includes pediculosis capitis, trichomycosis axillaris, peripilar keratin casts, monilethrix, and trichorrhexis nodosa. Wood light examination, KOH preparation testing, and fungal culture testing help in differentiating these conditions.1,2,7
Treatment of superficial infection of white piedra is best achieved by shaving off all of the hair in the affected areas and the use of a topical antifungal to the scalp. Ketoconazole shampoo is most commonly used for a period of several months. The specific treatment duration depends on the treatment response.1,2,5,6 However, if the patient refuses to shave his or her hair, oral daily itraconazole, 100 mg, is suggested in addition to the topical regimen.1,3,5 Treatment can be a therapeutic challenge, since several topical and systemic antifungal agents may not eliminate the infection completely.1,6