Ann Lab Med.  2012 Nov;32(6):438-441.

Subcutaneous Phaeohyphomycosis Caused by Exophiala salmonis

• Yoon YA
• Park KS
• Lee JH
• Sung KS
• Ki CS
• Lee NY

Abstract

We report a case of subcutaneous infection in a 55-yr-old Korean diabetic patient who presented with a cystic mass of the ankle. Black fungal colonies were observed after culturing on blood and Sabouraud dextrose agar. On microscopic observation, septated ellipsoidal or cylindrical conidia accumulating on an annellide were visualized after staining with lactophenol cotton blue. The organism was identified as Exophiala salmonis by sequencing of the ribosomal DNA internal transcribed spacer region. Phaeohyphomycosis is a heterogeneous group of mycotic infections caused by dematiaceous fungi and is commonly associated with immunocompromised patients. The most common clinical manifestations of subcutaneous lesions are abscesses or cystic masses. To the best of our knowledge, this is the first reported case in Korea of subcutaneous phaeohyphomycosis caused by E. salmonis that was confirmed by molecular analysis and identification of morphological characteristics. This case suggests that E. salmonis infections are no longer restricted to fish.

Keyword

Phaeohyphomycosis; Exophiala; Soft tissue infection; Sequence analysis; Korea

MeSH Terms

DNA, Ribosomal Spacer/genetics
Databases, Genetic
Diabetes Mellitus, Type 2/pathology
Exophiala/genetics/*isolation & purification
Humans
Male
Middle Aged
Phaeohyphomycosis/*diagnosis/microbiology
Sequence Analysis, DNA
DNA, Ribosomal Spacer

Figure

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  Fig. 1 Cystic mass on the left ankle. The swollen mass was soft, palpable, non-tender, and filled with pus.

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  Fig. 2 Colony morphology of Exophiala salmonis on the blood agar plates after 3 days incubation. Black colonies 1-3 mm in diameter can be observed along the streak line.

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  Fig. 3 Colony morphology of Exophiala salmonis on Sabouraud dextrose agar after 14 days incubation. The colony surface is brownish-black and velvety or felt-like. The reverse side of the colony is also black.

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  Fig. 4 Septated ellipsoidal or cylindrical conidia at the annellide. Septated hyphae with poorly differentiated or sometimes tubular, short flask-shaped annellides are observed (lactophenol cotton blue stain, ×400).

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