eMedicine Specialties > Dermatology > Fungal Infections

Piedra

Author: Robert A Schwartz, MD, MPH, Professor and Head, Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Coauthor(s): Rachel Altman, MD, Staff Physician, Department of Dermatology, UMDNJ-New Jersey Medical School
Contributor Information and Disclosures

Updated: Jun 12, 2009

Introduction

Background

Piedra, which means "stone" in Spanish, is an asymptomatic superficial fungal infection of the hair shaft. In 1865, Beigel¹ first described piedra in The Human Hair: Its Structure, Growth, Diseases, and Their Treatment; although, he may have been describing Aspergillus infection.

In 1911, Horta classified piedra into 2 types. The first is black piedra, which is caused by Piedraia hortae. The second is white piedra. The etiological agents of white piedra, originally named Pleurococcus beigelii and later Trichosporon beigelii, are now called Trichosporon asahii and 5 other species: Trichosporon ovoides, Trichosporon inkin, Trichosporon mucoides, Trichosporon asteroides, and Trichosporon cutaneum. These 6 organisms are all causative agents of white piedra. T asahii is considered most closely linked to white piedra, although some authorities believe T ovoides is the main agent of white piedra of the scalp. Use of the term T beigelli should be avoided.²

The 2 types of piedra occur in different climatic conditions. Black piedra is most common in the tropical regions of the world that have high temperatures and humidity. For example, black piedra may occur in many central South American countries, including Brazil, as well as in Southeast Asia. Black piedra is rare in the United States. White piedra is more common in temperate and semitropical climates, such as those in South America, Asia, Europe, Japan, and parts of the southern United States.

In addition, the black piedra and white piedra affect the hair in different body locations. Black piedra usually affects scalp hair, whereas white piedra more commonly affects pubic hair, axillary hair, beards, mustaches, and eyebrows and/or eyelashes. However, in Brazil, white piedra is reported to affect scalp hair most commonly.³ White piedra affects horses and monkeys, in addition to humans. Black piedra occurs in monkeys and humans.

Both types of piedra ultimately may lead to hair breaking because the shaft is weakened by cuticular penetration. In patients who are immunocompromised, dissemination of T asahii can occur, causing purpuric or necrotic cutaneous papules and nodules. Culture or biopsy samples from skin lesions may reveal the causative organism. Related organisms may be found on animal hair, in soil, or in stagnant water.⁴  Gonzalez et al documented outbreaks of clinical mastitis caused by T asahii in dairy herds. This intramammary infection of affected cows causes hyperthermia, swelling of the udder, and decreased milk production or agalactia; this infection can be fatal in cows.⁵

Pathophysiology

The environment and typical skin flora are the 2 main sources of infectious agents that cause piedra. The source of infection in black piedra, P hortae, appears to be in the soil; however, infection also has been traced to organisms in stagnant water and crops.^6,7 The source of infection for white piedra, typically T asahii, can be present in the soil, air, water, vegetable matter, or sputum or on body surfaces.⁴ However, the mode of infection in man is not clear. White piedra has been described in horses, monkeys, and dogs.⁸

Trichosporon species may also be causative agents of onychomycosis. A German study showed that among yeasts, they represented 10% of such infections.⁹ In addition, T asahii fungemia may develop in clinically deteriorated patients with or without an underlying hematological malignancy,¹⁰ as in a neutropenic patient with acute leukemia.¹¹

Frequency

United States

White piedra is quite common in parts of the southern United States and less so elsewhere in America. However, white piedra may be emerging as a commonly seen hair and scalp infection in the northeastern United States.¹²

International

Black piedra is most common in tropical regions such as South America, Far East, and the Pacific Islands. At one time, black piedra reportedly was endemic in Brazilian Indians living in the northern area of midwestern Brazil.¹³ This trend may have been linked to the Brazilian Indians' cultural use of plant oils in their hair.

White piedra is more common in temperate and semitropical climates, such as those in Asia, Europe, Japan, and parts of the southern United States.^14,15 White piedra caused by T cutaneum was identified in 5.8% of the children frequenting a day care in northeastern São Paulo State, Brazil.¹⁶

Mortality/Morbidity

Cosmetic morbidity occurs because piedra may affect the patient's body image; the hair shaft may break and/or the patient may need to shave the affected hair.

Race

In the United States, the occurrence of piedra may be higher in blacks than in whites; however, many cases may be underreported because nodules of piedra may be inconspicuous.¹⁷

Sex

Both sexes are affected equally. Black piedra initially was believed to be more common in men than in women; however, a study among the Zoro Indians of Brazil revealed no significant differences between the sexes.⁶ In another study among Brazilian Indians, black piedra affected both sexes equally.¹³

Twenty-three cases of scalp white piedra were described in Brazil, with a high incidence in women (87%) and preschool children aged 2-6 years (74%).⁸

Age

Individuals of all ages are affected. In a study of Brazilian Indians, persons of all ages were affected, from young children to adults older than 70 years, although black piedra infected young adults most frequently.¹³ In one series of 23 Brazilian patients with scalp white piedra, a high incidence was found in preschool children aged 2-6 years (74%).⁸

Clinical

History

White piedra shows irregular, white, cream-colored, or brown soft nodules or gelatinous sheaths along the hair shaft. They can be easily detached from the hair shaft. White piedra is found in the hair of the beard, moustache, genitals, and axilla. Eyebrow and eyelash involvement can also be present, while on the scalp, white piedra appears to be less common.

• Piedra may be asymptomatic in many patients.
• Patients may not be able to see the minute nodules that haphazardly develop on the hair shaft; however, they may feel the gritty nodules.
• Patients may hear a metallic sound when they brush their hair.¹⁸
• Assess the immune status of the patient because of the possibility of disseminated infection in a patient who is immunocompromised; T asahii, which is the most typical agent for white piedra, can cause disseminated infection in these patients. These systemic infections occur primarily in patients who have neutropenia and, rarely, in patients with AIDS.¹⁹ Cutaneous disseminated papulae or purpural nodules are frequently present in these patients.
• Black piedra may be used as a hair dye to darken hair; at least one San Blas (Panama) Cuna albino Indian chanter has been described as deliberately cultivating black piedra for cosmetic reasons.²⁰ She was careful to avoid oil use on her scalp, since it apparently removed this fungus.
• White piedra may have a synergistic coryneform bacterial infection.²¹ White piedra, although not commonly reported to infect scalp hair in North America, is an important consideration in the evaluation of scalp hair concretions. White piedra may affect the scalp, and in one case, it was the only site affected and was extensive.²² Rarely, Trichosporon species may be accompanied by Candida parapsilosis along hair shafts, although it is unclear if this is really a co-infection.
• A peculiar case has been described with white piedra spores packed inside empty pedicular nits were accidentally found on microscopic examination in a 42-year-old Indian woman who presented with hair loss.²³ It is remarkable to have pedicular nits impregnated with spores of white piedra.

Physical

• Findings in black piedra may include the following:
  • Black piedra consists of darkly pigmented, firmly attached nodules that vary in size to as large as a few millimeters in diameter. The nodules feel hard.
  • The most commonly affected area of the body is the scalp hair. Black piedra less frequently affects beards, mustaches, and the pubic hair.
  • The fungus grows into the hair shaft; ultimately, it may cause hair breakage because of structural instability.
• Findings in white piedra may include the following:
  • White piedra consists of lightly pigmented, loosely attached nodules or gelatinous sheaths that have a soft texture.
  • The most commonly affected areas of the body are beards, mustaches, pubic and axillary hair, and eyelashes and eyebrows.
• Hair breakage occurs in both forms of piedra.
• In both varieties of piedra, the surrounding skin is healthy.

Causes

T asahii can cause white piedra and occasionally an onychomycosis.^24,25 The genus Trichosporon Behrend consists of 6 human pathogenic species: T asahii, T mucoides, T ovoides, T asteroides, T cutaneum, and T inkin and all of which belong to the class Basidiomycetes.^8,26 These species are the causative agents of piedra and other superficial infections as well as mucosa-associated systemic mycosis.²⁶

In Brazil Trichosporon ovoides and Trichosporon inkin are common causative agents of white piedra, producing nodules in genital hair or on the scalp.²⁷ Of Trichosporon species isolated from 10 clinical samples in a 2008 study, T ovoides was predominant, being found in 7 samples, while T inkin was identified just in 2 of them.

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