Description

This blog was written by Maha Aladwan, a master's student in the Department of Biological Sciences at Western Illinois University.

Piedra is an asymptomatic superficial fungal infection of the hair shaft which leads to 

breakage of the hair itself. The first isolated case of black piedra was in 1876 in Colombia by 

Ozorio and Arango, and the fungus was cultured by Desenne in 1878 (3). Then,  Horta (1911) 

claimed that there were two types of piedra. The first type is black piedra, which is caused by 

Piedraia hortae. The second type is white piedra. Black piedra affects scalp hair, beard, 

mustache and pubic hair. The phylum of the causing agent is Ascomycota. In addition, black 

piedra is most common in the tropical regions of the World that have high temperatures and 

humidity, such as South American, Brazil and Southeast Asia (3-7).


 The macroscopic features of  black piedra are slow growing colonies, folded, small and dark brown. Also, they are covered with short aerial hyphae ( Figure 1). Black piedra produce a reddish brown diffusible pigment (Fonseca and de Area Leao in 1928). Microscopic features are septate hyphae, asci, and ascostromata. Hyphae are dark and have chlamydoconidium-like cells (doctor fungus). The Ascostromata is a pseudoparenchymatous structures that are black in color and the asci are ellipsoid, solitary and contain 8 ascospores. Ascospores are hyaline to darkly pigmented and contained one-celled (3).

Figure 1: Black piedra have folded, small and dark brown and short hyphae.

Diagnostic description

According to university of Adelaide and Iranian Association of Clinical Laboratory Doctors, there are different ways  to diagnose this infection:

1-Direct Microscopy: using 10% KOH and parker ink or calcofluor white. Packed mass of brown pigmented branching hyphae can be observed surrounding the asci, each of fungus holds eight ascospores.

2- Culture: using primary isolation media such as Sabouraud's dextrose agar. The fungus will produce after 2-3 weeks a dark brown to black colonies with folded surface and a flat margin (Figure 2) (4-7)

Figure 2: black colonies are white folded surface and a flat margin

Distribution

           The geographic distribution of black piedra is limited to tropical and subtropical areas that have high temperatures and humidity,  for example : South and Central America and South-East Asia (Ann Dermatol Venereol, 1987). Black piedra have also been reported  in Africa and the South Pacific islands. Kaplan studied the infection in primate pelts. He found it in 57 out of 94 (60,6%) pelts from Asia; in 83 out of 109 (78,1%) from the New World; and in 58 out of 202 (28,7%) from Africa and only 2 cases were found in 33 primates in zoos in the United States (2).

Habitat

           Black piedra is found in soil, particularly in tropical areas. Also, it is mixed with coryneform bacteria and occasionally with Trichosporon spp. However, the infection also has been traced to organisms in stagnant water and crops. Munich in 1937 said that black piedra occurs in animals as well as in humans. Moreover, piedra was also found on the hairs of 5 out of 7 chimpanzee pelts from the Cameroon (6).

Epidemiology

               Robert A Schwartz claimed that black piedra affects both sexes (man and woman).  A study among the Zoro Indians of Brazil revealed no significant differences between the sexes. In another study among the Zoro Indians of Brazil, black piedra affected both sexes equally.  In addition, a study among the Zoro Indians of Brazil showed that young children to adults older than 70 years were affected of Black Piedra (9).

Clinical Manifestations.

According to Iranian Association Of  Clinical Laboratory Doctors, clinical manifestations include :

   - Affected hairs: from 4 to 8 firmly attached nodules (d: 1-2 mm).

-          - Nodules: oval or elongated, hard, dark brown to black , many surround the hair.

-          - Uncovered part of the hair shafts.

-          - Often broken hairs. 

         Treatment.

According to Iranian Association Of  Clinical Laboratory Doctors, there are different treatments of Black Piedra:

-          - Clipping the hairs.

-          - Using a topical salicylic acid preparation.

-          - Using a topical imidazole cream.                                                                                                         

        -  Application of topical selenium sulphide 

     

          Clinical Cases.

          1-First Case.

James Marshall, M.D ( 1961) noted a case in a four-year-old white girl. The hair had fallen out in patches and there was little scalp hair. The girl's scalp hair was short, coarse, dry, dull and sparse. At the back of the head, the hairs were about 1 cm in length, in front about 5 cm. Also,  studies showed small black, hard nodules containing dark, branching hyphae resembling arthrospores and small asci with several fusiform ascospores. The infection was treated  with 10% potassium hydroxide for 10 - 15 minutes. Also, the nodule was composed of closely septate. The fungus was isolated both microscopically and in cultural. As a result,  the fungus was identified as Piedraia hortai. (Figure3)

Figure 3: girl's hair has black piedra

2-Second case.

            According to the British Journal of Dermatology (1994)  a 23-year-old man had typical clinical signs of black piedra on his scalp after his return from India. There were black nodules around the hair shafts. Also, the crushed nodules revealed numerous asci and ascospores on microscopy. He was treated with oral terbinafine 250 mg daily for 6 weeks.  (1)

References

1-   British Journal of Dermatology. (1994, Apr). Black piedra: the first case treated with terbinafine (lamisil). US National Library of Medicine National Institutes of Health. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/8186138

2-      Marshall James  (1961). Black piedra in a child with pili torti, bamboo hair ad cogenital ichthyosiform erythroderma.. Retrieved from http://archive.samj.org.za/1961 VOL XXXV Jan-Jun/Articles/03 March/3.1

3-      Fonseca. , & de Area Leao, (1928). Piedraia spp. Doctor Fungus . Retrieved from http://www.doctorfungus.org/thefungi/piedraia.php

4-      Zibafar, E. Iranian Association of Clinical Laboratory Doctors. Retrieved from http://www.iacld.ir/DL/modavan/mycology/92/piedra&tineanigradrzibafar.pdf

5-      Figueras, M. J., & Guarro, J. Ultrastructural aspect of the keratinolytic activity of piedra. . Retrieved from http://www.dermatophytes.reviberoammicol.com/p136141.pdf

6-      Richardson, M. D., & Warnock, D. W. Fungal infection. Retrieved from http://books.google.com/books?id=TLhI9NjABuYC&pg=PT176&lpg=PT176&dq=Habitat of Piedraia hortae&source=bl&ots=nEAUYUGd1X&sig=bDtt23winKZ3ycCN7IfWAQTG0EU&hl=ar&sa=X&ei=gCE5U8jNJJDlqAGQ7IHAAw&ved=0CEUQ6AEwAw

7-      mycology online. (n.d.). Retrieved from http://www.mycology.adelaide.edu.au/Mycoses/Superficial/Black_piedra/

8-      wisegeek clear answers for common questions. (n.d.). Retrieved from http://www.wisegeek.com/what-is-piedra.htm

Schwartz, R. A. (2013, 9 26). Piedra. Medscape. Retrieved from http://emedicine.medscape.com/article/1092330-overview