AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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. It 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 2 types of 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, it 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.

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.¹⁴

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

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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.¹⁵
• 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. 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.¹⁶ 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.¹⁷ 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.¹⁸ 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.¹⁹ 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.^{20, 21} 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, 22} These species are the causative agents of piedra and other superficial infections as well as mucosa-associated systemic mycosis.²²

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Pediculosis
Nits
Hair casts
Developmental defects of the hair shaft

Trichomycosis axillaris infection - Unlike the organisms that cause piedra, T axillaris fluoresces under ultraviolet illumination.

Tinea capitis - Unlike piedra, tinea capitis affects the base of the hair shaft and the follicle.

White piedra can be clinically indistinguishable from monilethrix, trichorrhexis nodosa, and trichoptilosis.

Hand eczema - This condition is a superficial infection caused by Trichosporon species that can mimic hand eczema in one who is immunocompromised.

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Staining
• • Place hair shaft nodules into a 10-15% potassium hydroxide preparation on a glass slide. A fungal stain, such as chlorazol black E stain or Parker blue-black ink may be added to highlight the hyphae.
  • If the nodule is from black piedra, tightly packed and pigmented hyphae, asci, and ascospores are seen attached to the hair shaft.
  • If the nodule is from white piedra, darkly stained and loosely arranged hyphae, blastoconidia, and arthroconidia are seen attached to the hair shaft.
• Culturing
  
  
  • P hortae, the cause of black piedra, grows slowly on Sabouraud dextrose agar and is not inhibited by cycloheximide. Microscopic examination reveals septate hyphae, chlamydospores, and irregularly shaped hyphal elements. These cultures are of the asexual phase of the fungus. Organisms in the sexual phase are difficult to grow in culture.
  • T asahii, the typical cause of white piedra, rarely grows on Sabouraud dextrose agar because of inhibition by cycloheximide, which is present in dermatophyte test medium and in Mycosel and mycobiotic agars. In addition, Trichosporon species grow best at 28-30°C.

Histologic Findings

In black piedra, the dark nodules are composed of different components based on the area of the body in which they are located. Black piedra is distinguished by ascospores borne in a subglobose ascus in groups of 8. The periphery of the nodule has regularly aligned hyphae and arthroconidia.²³ P hortae is one of the few pathogenic human fungi that produce sexual spores in its parasitic phase.

White piedra is characterized by discrete-to-coalesced nodules that typically are white, cream, or brown.^{14, 24} Nodules on the hair shaft often appear amorphous, but may be outlined by hyaline arthroconidia, 2-4 septate hyphae, and differentiated blastoconidia that arise from loosely packed hyphae. Sexual spores are not known to be present.¹⁴ Fungal structures stain easily with Parker blue-black ink.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Shaving or cutting the hair is the treatment of choice. Antifungal agents and terbinafine also are used in the treatment of piedra.

• Black piedra is treated by using oral terbinafine.
• White piedra can be treated by using topical antifungals, including imidazoles, ciclopirox olamine, 2% selenium sulfide, 6% precipitated sulfur in petroleum, chlorhexidine solution, Castellani paint, zinc pyrithione, and amphotericin B lotion.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Treatment of white piedra can be a therapeutic challenge. Several topical and systemic antifungal agents may not eradicate the disorder. However, they should be tried, as scalp and hair infection may sometimes be successfully treated with a combination of oral azole antifungals and shampoos without shaving the scalp.¹² Therapy with oral itraconazole for the treatment of uncomplicated white piedra affecting the scalp hair may be a good choice if topical remedies fail.²⁵

Drug Category: Antifungal agents

The mechanism of action of antifungals may involve an alteration of RNA and DNA metabolism or an intracellular accumulation of peroxide that is toxic to the fungal cell.

Drug Name	Miconazole 2% (Micatin, Monistat-Derm, Femizole-7, Lotrimin)
Description	Imidazole used in the treatment of tinea cruris. Available over the counter. Cream, solution or spray, lotion, and powder forms are available.
Adult Dose	Apply topically to affected areas bid for 4 wk or until condition resolves
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Discontinue if sensitivity or chemical irritation occurs; for external use only; avoid contact with eyes

Drug Name	Ketoconazole 2% cream (Nizoral cream)
Description	Imidazole broad-spectrum antifungal agent; inhibits synthesis of ergosterol, causing cellular components to leak, resulting in fungal cell death.
Adult Dose	Apply topically to affected areas qd for 2-4 wk or until condition resolves
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Discontinue if sensitivity or irritation develops; for external use only; avoid contact with eyes

Drug Name	Econazole 1% (Spectazole)
Description	Effective in cutaneous infections. Interferes with RNA and protein synthesis and metabolism. Disrupts fungal cell-wall permeability, causing fungal cell death.
Adult Dose	Apply topically to affected areas qd until condition resolves
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Discontinue if sensitivity or irritation develops; for external use only; avoid contact with eyes

Drug Name	Terbinafine (Lamisil)
Description	Allylamine derivative that inhibits squalene epoxidase, a key enzyme in sterol biosynthesis in fungi. This inhibition results in a deficiency in ergosterol within the fungal cell wall that causes fungal cell death. Terbinafine is available by prescription only. Some clinicians reserve the use of this drug for more widespread and/or resistant infections because of its broad coverage and cost. This medication is effective and well tolerated in children.
Adult Dose	White piedra: Apply topically to the affected area qd for 2 wk or until condition resolves Black piedra: 250 mg/d PO; not to exceed 12 wk
Pediatric Dose	Topical: Administer as in adults Oral: 12-20 kg: 62.5 mg/d 20-40 kg: 125 mg/d >40 kg: 250 mg/d Treatment duration as in adults
Contraindications	Documented hypersensitivity
Interactions	Possible interactions with drugs metabolized by the CYP-450 (P-450) 2D6 enzyme (eg, tricyclic antidepressants, propranolol, theophylline); may decrease cyclosporin levels; rifampin increases clearance; cimetidine may increase toxicity
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Reduce oral dose in renal insufficiency; discontinue if hepatobiliary dysfunction, neutropenia, Stevens-Johnson syndrome, or changes in ocular lens or retina develop; discontinue topical use if chemical irritation develops Monitor patient response and adjust caffeine dosage during combined treatment with terbinafine; observe for signs of caffeine toxicity (headache, agitation, insomnia, diuresis, fever)

Drug Name	Oxiconazole 1% (Oxistat)
Description	Damages fungal cell wall membrane by inhibiting biosynthesis of ergosterol. Increases membrane permeability, causing nutrients to leak out, resulting in fungal cell death.
Adult Dose	Apply to affected area qd/bid until condition resolves
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Discontinue if sensitivity or chemical irritation occurs; for external use only; avoid contact with eyes

Drug Name	Sulconazole 1% (Exelderm)
Description	Broad-spectrum imidazole derivative with antifungal and antiyeast activity. For topical use. Inhibits growth of common pathogenic dermatophytes.
Adult Dose	Apply to affected areas qd/bid for 2-4 wk or until condition resolves
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Discontinue if sensitivity or chemical irritation occurs; for external use only; avoid contact with eyes

Drug Name	Itraconazole (Sporanox)
Description	Fungistatic activity. Synthetic triazole antifungal agent that slows fungal cell growth by inhibiting cytochrome P-450–dependent synthesis of ergosterol, a vital component of fungal cell membranes. Absorption improved with food and in presence of normal gastric acidity. Patients should be cautioned against ingesting grapefruit juice while on itraconazole therapy (decreased oral bioavailability of itraconazole). Discontinue if sensitivity or chemical irritation occurs; for external use only; avoid contact with eyes.
Adult Dose	100 mg PO qd until culture negativity achieved
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; congestive heart failure or history of congestive heart failure (itraconazole cap for treatment of superficial fungal infections), concurrent administration with cisapride, midazolam, triazolam, lovastatin, dofetilide, pimozide, levacetylmethadol (levomethadyl), quinidine, lovastatin, simvastatin, and ergot alkaloids metabolized by CYP3A4 (eg, dihydroergotamine, ergometrine [ergonovine], ergotamine, methylergometrine [methylergonovine]); women contemplating pregnancy
Interactions	As CYP3A4 inhibitor (P450 metabolism), many drugs have interactions when coadministered with itraconazole; avoid alcohol use because disulfiramlike reaction may occur; antacids may reduce absorption; edema may occur with coadministration of calcium channel blockers (eg, amlodipine, nifedipine); hypoglycemia may occur with sulfonylureas; high doses may increase tacrolimus and cyclosporine plasma concentrations; rhabdomyolysis may occur with coadministration of HMG-CoA reductase inhibitors (eg, lovastatin, simvastatin); coadministration with cisapride can cause cardiac rhythm abnormalities and death; may increase digoxin levels; coadministration may increase plasma levels of midazolam or triazolam; phenytoin and rifampin may reduce levels (phenytoin metabolism may be altered) Reduced itraconazole plasma concentrations reported with concurrent use of H2 antagonist and aluminum-, calcium-, or magnesium-containing products (administer aluminum-, calcium-, or magnesium-containing products at least 1 h before or 2 h after itraconazole cap); enhances anticoagulant effects of coumarinlike drugs
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Caution in hepatic insufficiencies; adverse effects include headache, nausea, vomiting, reversible elevation of liver enzyme levels, hepatotoxicity, hallucinations, hypokalemia, heart failure, edema, congestive heart failure, and neutropenic disorder; oral solution and oral capsules not to be used interchangeably; injection not for use in patients with CrCl <30 mL/min, and use with caution in patients with CrCl of 30-80 mL/min

Drug Name	Ciclopirox (Loprox)
Description	Interferes with DNA, RNA, and protein synthesis by inhibiting the transport of essential elements in fungal cells.
Adult Dose	Massage into affected area bid until condition resolves
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Avoid contact with eyes and other internal routes

Drug Name	Naftifine (Naftin)
Description	Indicated for the treatment of tinea corporis, tinea cruris, and tinea pedis. Broad-spectrum antifungal agent that appears to interfere with sterol biosynthesis by inhibiting the enzyme squalene 2,3-epoxidase. This inhibition results in decreased amounts of sterols, causing cell death. If no clinical improvement occurs after 4 wk of treatment, reevaluate patient.
Adult Dose	Gently and sparingly massage the cream or gel into affected area and surrounding skin qd/bid for 2-4 wk or until condition resolves
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Discontinue use if sensitivity or chemical irritation occurs; for external use only; avoid contact with eyes

Drug Category: Dermatologic agents

These agents may be effective in treating white piedra.

Drug Name	Carbol-fuchsin (Castellani Paint)
Description	First-aid antiseptic and drying agent. Active ingredient is phenol 1.5%. Inactive ingredients are water, SD alcohol 40B (13%), resorcinol, acetone, and basic fuchsin.
Adult Dose	Spray or apply to affected area qd/bid
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Avoid contact with clothing; stain slowly wears off; not for application on eroded skin, or large areas; infants may be more sensitive than adults to phenol component

Drug Name	Chlorhexidine (Hibiclens, PerioGard)
Description	Effective, relatively safe, and reliable topical antiseptic. A polybiguanide with bactericidal activity; usually is supplied as a gluconate salt. At physiologic pH, the salt dissociates to a cation that binds to bacterial cell walls.
Adult Dose	Rinse affected area with water, apply sufficient amount to cover affected area, wash gently, then rinse
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Corneal damage may occur; skin irritation, ototoxicity resulting in deafness (when used around the ear), phototoxicity, and/or allergic reactions rare when used to clean superficial wounds (does not cause additional tissue injury or delay healing)

Drug Name	Pyrithione zinc (DHS Zinc, Zincon, Head & Shoulders)
Description	Cytostatic agent that reduces cell turnover rate. Strongly binds to hair and external skin layers.
Adult Dose	Apply shampoo and rinse; use qd until condition resolves; use as with selenium sulfide
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	For external use only; do not apply to eyes

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

• Spontaneous remissions are common.
• Treatment is effective in patients without spontaneous remission.
• Removal of hair is curative and requires no follow-up treatment.
• Recurrences are rare.

Complications

• The most common complication is the loss of the structural integrity of the hair shaft, which leads to breakage.

Prognosis

• The prognosis after treatment is good.
• Removal of the affected hair is usually curative, with few recurrences.
• Even without treatment, spontaneous remissions can occur.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to diagnosis piedra may lead to broken hair in patients and subsequent emotional distress.
• Misdiagnosis of pediculosis or tinea capitis may result in unwarranted emotional distress in patients.
• Misdiagnosis of pediculosis in children may result in their being banned from attending school because of the infectious nature of pediculosis and the possibility of an epidemic in the school.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Beigel H. The Human Hair. In: Its Structure, Growth, Diseases, and Their Treatment. London, England: Renshaw; 1869.
2. Schwartz RA. Superficial fungal infections. Lancet. Sep 25-Oct 1 2004;364(9440):1173-82. [Medline].
3. Londero AT, Ramos CD, Fischman O. White piedra of unusual localization. Sabouraudia. Oct 1966;5(2):132-3. [Medline].
4. Rippon JW. Medical Mycology. In: The Pathogenic Fungi and the Pathogenic Actinomycetes. 142. 3^rd ed. Philadelphia, Pa: WB Saunders; 1988:163-8.
5. Gonzalez RN, Wilson DJ, Sickles SA, Zurakowski MJ, Weybrecht PM, Walsh AK. Outbreaks of clinical mastitis caused by Trichosporon beigelii in dairy herds. J Am Vet Med Assoc. Jan 15 2001;218(2):238-42. [Medline].
6. Coimbra Júnior CE, Santos RV. Black piedra among the Zoró Indians from Amazônia (Brazil). Mycopathologia. Jul 1989;107(1):57-60. [Medline].
7. Kwon-Chung KJ, Bennett JE. Piedra (tinea nodosa trichomycosis nodularis, trichomycosis nodosa, Beigel's disease, Chignon disease). In: Medical Mycology. Philadelphia, Pa: Lea & Febiger; 1992:183-90.
8. Pontes ZB, Ramos AL, Lima Ede O, Guerra Mde F, Oliveira NM, Santos JP. Clinical and mycological study of scalp white piedra in the State of Paraiba, Brazil. Mem Inst Oswaldo Cruz. Jul 2002;97(5):747-50. [Medline].
9. Mügge C, Haustein UF, Nenoff P. [Causative agents of onychomycosis--a retrospective study]. J Dtsch Dermatol Ges. Mar 2006;4(3):218-28. [Medline].
10. Karabay O, Madariaga MG, Kocoglu E, Ince N, Kandirali E. Trichosporon asahii Fungemia in a Patient with Non-Hematological Malignancy. Jpn J Infect Dis. Apr 2006;59(2):129-31. [Medline].
11. Bayramoglu G, Sonmez M, Tosun I, Aydin K, Aydin F. Breakthrough Trichosporon asahii Fungemia in Neutropenic Patient with Acute Leukemia while Receiving Caspofungin. Infection. Feb 2008;36(1):68-70. [Medline].
12. Kiken DA, Sekaran A, Antaya RJ, Davis A, Imaeda S, Silverberg NB. White piedra in children. J Am Acad Dermatol. Dec 2006;55(6):956-61. [Medline].
13. Fischman O. Black piedra among Brazilian Indians. Rev Inst Med Trop Sao Paulo. Mar-Apr 1973;15(2):103-6. [Medline].
14. Kalter DC, Tschen JA, Cernoch PL, McBride ME, Sperber J, Bruce S, et al. Genital white piedra: epidemiology, microbiology, and therapy. J Am Acad Dermatol. Jun 1986;14(6):982-93. [Medline].
15. Elgart ML. Unusual subcutaneous infections. Dermatol Clin. Jan 1996;14(1):105-11. [Medline].
16. Moyer DG, Keeler C. Nnote on culture of black peidra for cosmetic reasons. Arch Dermatol. Mar 1964;89:436. [Medline].
17. Youker SR, Andreozzi RJ, Appelbaum PC, Credito K, Miller JJ. White piedra: further evidence of a synergistic infection. J Am Acad Dermatol. Oct 2003;49(4):746-9. [Medline].
18. Taj-Aldeen SJ, Al-Ansari HI, Boekhout T, Theelen B. Co-isolation of Trichosporon inkin and Candida parapsilosis from a scalp white piedra case. Med Mycol. Feb 2004;42(1):87-92. [Medline].
19. Ghorpade A. Surrogate nits impregnated with white piedra--a case report. J Eur Acad Dermatol Venereol. Jul 2004;18(4):474-6. [Medline].
20. Elmer KB, Elston DM, Libow LF. Trichosporon beigelii infection presenting as white piedra and onychomycosis in the same patient. Cutis. Oct 2002;70(4):209-11. [Medline].
21. Manzano-Gayosso P, Hernández-Hernández F, Méndez-Tovar LJ, Palacios-Morales Y, Córdova-Martínez E, Bazán-Mora E, et al. Onychomycosis Incidence in Type 2 Diabetes Mellitus Patients. Mycopathologia. Mar 29 2008;[Medline].
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Article Last Updated: Apr 30, 2008