Superficial cutaneous Trichosporon asahii infection in an immunocompetent host

Abstract

A 16-year-old schoolgirl presented with a complaint of enlarging erythematous and mildly pruritic patches located on the buttocks of 2 years’ duration. She had been treated with a potent topical corticosteroid for many months without apparent benefit. She was in otherwise good health. She denied a history of hair infection, previous eruptions, asthma, or hay fever. No one in her family or friends had similar lesions. She had no pets in her house. Examination revealed the presence of two erythematous and slightly indurated plaques measuring approximately 16 cm × 9 cm and 6 cm × 11 cm in diameter on her right and left buttocks, respectively (Fig. 1). Similar progressively enlarging lesions were present on the dorsum of her right hand, extending to the extensor aspect of the forearm and to the lateral, inner, palmar, and extensor aspects of the second, third, and fourth fingers, and on the dorsum of her left hand up to the flexor aspect of the wrist. A few erythematous papules clustering around these plaques in a satellite fashion were also detectable. Her scalp, pubic, axillary, eyebrow, and eyelash hair appeared normal with no concretions or soft, lightly pigmented, white to light-brown, loosely attached, irregularly spaced nodules. There was no regional or generalized lymphadenopathy or hepatosplenomegaly. Routine laboratory investigations, human immunodeficiency virus (HIV) testing, and standard patch tests were negative. Figure 1Open in figure viewerPowerPoint Erythematous and slightly indurated plaques on the right and left buttocks A skin biopsy specimen from the right buttock showed parakeratosis and acanthosis in the epidermis, with some neutrophils within the parakeratotic crust, and a mild inflammatory infiltrate in the dermis. In the stratum corneum, fungal hyphae were detectable by periodic acid–Schiff (PAS) staining (Fig. 2). Direct microscopic examination with 15% potassium hydroxide (KOH) preparation of scale showed pseudohyphae. Two mycotic cultures were obtained: the first on Sabouraud dextrose agar (SDA) medium (2% glucose, 1% mycologic peptone, 0.5% yeast extract, 1.5% agar; Oxoid Ltd, Basingstoke, UK) supplemented with chloramphenicol (Sigma, St. Louis, MO, USA) and cycloheximide (Sigma, St. Louis, MO, USA) incubated for 2 weeks at 25 °C; the second on SDA medium supplemented with chloramphenicol and gentamycin (Oxoid Ltd, Basingstoke, UK) incubated for 2 weeks at 30 °C (Fig. 3). Figure 2Open in figure viewerPowerPoint Skin biopsy from a tissue specimen in which fungal hyphae were detectable in the stratum corneum (periodic acid–Schiff, ×40) Figure 3Open in figure viewerPowerPoint Mycologic culture of isolated Trichosporon sp. (Sabouraud dextrose agar medium with chloramphenicol and gentamycin) The cultures yielded cream-colored, wrinkled colonies, microscopic examination (with lactophenol cotton blue) of which showed true hyphae, pseudohyphae, a few blastoconidia, and rectangular arthroconidia typical of Trichosporon sp. (Fig. 4). These colonies were identified as Trichosporon asahii by cornmeal agar medium with the addition of Tween-80, according to the Dalmau plate technique (Fig. 5), and on API 20C AUX assimilation assay (BioMerieux, Inc., Lyon, France). Figure 4Open in figure viewerPowerPoint Features of Trichosporon sp. at microscopic examination (lactophenol cotton blue stain, ×100) Figure 5Open in figure viewerPowerPoint Morphologic characteristics of Trichosporon asahii (cornmeal agar medium with the addition of Tween-80, ×40) The patient was given oral itraconazole (200 mg/day) and topical tioconazole cream for 6 weeks, which produced complete clinical and mycologic cure (Fig. 6). No relapse was observed at the 6-month follow-up. Figure 6Open in figure viewerPowerPoint Clinical aspect after treatment