Piedra, also known as trichomycosis nodularis is a common asymptomatic fungal infection of hair shaft. Two types of piedra have been described namely black piedra and white piedra. Both types of hair fungus ultimately may lead to hair breaking because the shaft is weakened by cuticular penetration.
Black piedra is caused by Piedraia hortae and is characterized by the presence of firmly attached, black/brown, hard nodules on the hair shaft. It is commonly seen in scalp hair, less frequently observed in the beard, moustache and pubic hair. Nodules may be seen on the frontal scalp and vary in size ranging from 1mm or more in diameter. As fungus grown in the hair shaft, the hair may break easily. If untreated the infection may last for years.
White piedra is caused by species of Trichosporon genus and is characterized by the presence of loosely attached whitish/ light-brown or cream colored soft nodules on the infected hair shaft. Their size may vary from microscopic to 1 mm in diameter. White piedra usually affects facial (beard, mustaches, eyelashes and eyebrows) underarms and genital hairs and less commonly scalp. As white piedra affects outer lipid layer, the soft white nodules can be easily detached from hair shaft. Broken hair is less commonly seen than black piedra.
How is it diagnosed?
Most diagnosis is based on direct clinical as most cases are characteristics. If there is confusion fungal testing can be done to exclude other disease like trichomycosis axillaris.
Treatment of Piedra
Shaving the infected hair is the best and simplest treatment and is curative therapy for both cases of white piedra and black piedra. Topical uses of anti-fungal medications like 2% ketoconazole, 1% terbinafine, 2% miconazole for at-least 2-3 weeks may also aid in the cure and prevent relapse. To achieve more successful results, Alternate days shampooing with antifulgal shampoos in combination with above topical cream and lotions may be needed. In severe and unresponsive oral antifungal medications like itraconazole may be given along with topical medications.