White piedra, black piedra, tinea versicolor, and tinea nigra: contribution to the diagnosis of superficial mycosis

Abstract

Superficial mycoses are fungal infections restricted to the stratum corneum and to the hair shafts, with no penetration in the epidermis; they are: white piedra, black piedra, tinea versicolor, and tinea nigra. This study presents images of mycological tests performed in the laboratory, as well as exams performed at the authors office, in order to improve the dermatologist's knowledge about the diagnosis of these dermatoses, which are common in many countries.

Figure 1

Clinical appearance of actual superficial mycoses. (A) White piedra: whitish nodule attached to the hair shaft. (B) Black piedra: darkened nodule attached to the hair shaft. (C) Tinea nigra: brownish macula on children’s palms. (D) Pityriasis versicolor: scattered maculas on the abdomen (D1), which become more evident after skin stretching (Zireli’s sign – D2)

Figure 2

Mycological examinations of white piedra: (A1) Optical microscopy (x40) offering a detailed illustration of the light color nodule attached to the pillar shaft. (A2) Optical microscopy (x100) illustrates the yeasts the make up the structure on the edge of the nodule. (B) Culture Mycosel medium (Difco, USA) with yeast-like colony, with the cerebriform filamentous appearance. (C) Microgrowth demonstrates yeasts with blasto-arthrospores, typical of Trichosporon sp

Figure 3

Mycological examinations of black piedra: (A) Optical microscopy (x40) offering a detailed illustration of the dark nodule attached to the pillar shaft. (B) Culture Mycosel medium (Difco, USA) with dematiaceous colony. (C) Optical microscopy (x100) identifying the ascus, round structures typical of parasitism caused by Piedraia hortae

Figure 4

Mycological examinations for tinea nigra: (A) Direct mycological examination of a sample collected through skin lesion scraping, clarified with KOH 10%, illustrating dematiaceous septate hyphae. (B) Culture Mycosel medium (Difco, USA) with dematiaceous colony with a waxy appearance. (C) Microgrowth revealing dematiaceous yeasts with binary fission, typical of Hortaea werneckii

Figure 5

Mycological examinations for pityriasis versicolor: (A) Direct mycological examination of a sample collected through skin lesion scraping, clarified with KOH 10%, illustrating yeasts grouped in a “grape bunch” format, and of short and thick pseudo-hyphae. (B) Sabouraud agar culture, enriched with olive oil, with beige yeast-like colony. (C) Yeasts grouped with short base single budding, with “bowling pin” appearance, stained by the hematoxylin eosin method, typical of Malassezia sp microgrowth

Figure 6

Patient exhibiting pityriasis versicolor lesions in the inguinal region (A), under Wood lamp, reveals silver fluorescence (B)

Figure 7

Dermatoscopy of tinea nigra palmar lesion under polarized light (A) and polarized light dermatoscopy performed on child with whitish nodules attached to the hair (B1), illustrating structures that are similar to those viewed in optical microscopy (B2)