Chromomycosis due to Exophiala jeanselmei in a renal transplant recipient

ARTICLE

Auteur(s) : Carmen PEÑA-PENABAD¹, María Teresa DURÁN², María Teresa YEBRA³, Jesús RODRÍGUEZ-LOZANO¹, Vanessa VIEIRA¹, Eduardo FONSECA¹

¹ Department of Dermatology, Complejo Hospitalario Juan Canalejo, Servicio de Dermatología, Xubias de Arriba, 84, 15006. a Coruña, Spain. 
² Department of Microbiology, Complejo Hospitalario Juan Canalejo, Coruña, Spain 
³ Departments of Pathology, Complejo Hospitalario Juan Canalejo, Coruña, Spain

Article accepted 28/02/2003

Chromomycosis is a cutaneous infection caused by dematiaceous (dark-pigmented) fungi. This mycosis has been individualized as pheohyphomycosis by its clinical and histopathological characteristics [1]. The aetiologic agents classically referred as causing chromomycosis are Fonsecaea pedrosoi, Cladosporium carrionii, Phialophora verrucosa, Fonsecaea compacta and Rhinocladiella aquaspersa, Fonsecaea pedrosoi being the fungus which produces most cases [2, 3]. In our environment, four of the five published cases [4-7] were due to F. pedrosoi.
Occasionally, other fungi can produce chromomycosis [8], and Exophiala has exceptionally been cultured in lesion samples of this mycosis [9-12].

Case report

A 58-year-old white Spanish male presented in July 2001 with a painless lesion on his right hand that had appeared five months previously. The lesion had been excised in June 2001, but recurred rapidly. He had suffered renal failure after a poststreptococcal glomerulonephritis and received a renal transplant in September 2000. He had developed pulmonary aspergillosis that was treated with itraconazole and amphotericin B. At presentation he was receiving immunosuppressive treatment with prednisone, tacrolimus and mycophenolate mofetil.
Physical examination revealed a plaque-like verrucous crusted lesion measuring 13 by 10 mm, located on the back of his right hand (Fig. 1). No regional adenopathies were detected.
Histopathologic examination revealed a pseudoepitheliomatous hyperplasia of the epidermis, dermal and intraepidermal microabscesses and a dense granulomatous infiltration in the dermis, with numerous giant cells. H&E stain showed dark brown, thick-walled, ovoid or spherical spores varying in size from 6 to 12 μm and lying either singly or in chains or clusters. Sclerotic bodies were observed within giant cells, as well as free in the dermis and the abscesses (Fig. 2). Spores were better visualised in sections stained with PAS or methenamine silver stain. The pus and the biopsied tissue were cultured on Sabouraud dextrose agar with and without chloramfenicol and cicloheximide at 30°C. After four days of incubation the cultures grew a brownish black, initially moist but soon velvety mold on all the media (Fig. 3a). Lactophenol preparations of slide cultures on potato-dextrose agar at 30°C showed after 14 days of incubation septate hyphae with numerous slender tubular, sometimes branched conidiophores, characteristically tapered to a narrow, elongated tip. The conidia (1-3 x 1-5 μm) were subglobose to ellipsoidal to cylindrical and gathered in clusters at the end and sides of the conidiophores and at points along the hyphae (Fig. 3b). The mold decomposed tyrosine but not casein nor xanthine, assimilated potassium nitrate, grew at 30°C and more slowly at 37°C, but did not grow at 42°C. It was identified as Exophiala jeanselmei.
The strain was sent to a referrence laboratory that confirmed that the fungus was E. jeanselmei and investigated the susceptibility to antifungal drugs. Minimal inhibitory concentrations readings at 100% of inhibition at 30°C after 96 hours of incubation were: amphotericin B, 1 μg/ml; itraconazole, 4 μg/ml; ravuconazole, 4 μg/ml; voriconazole, 4 μg/ml; fluconazole, 128 μg/ml and terbinafine, 0.06 μg/ml.
Oral itraconazole, 200 mg/day, was started, and tacrolimus dosage was diminished. The lesion gradually decreased and became less verrucous. One month later, examination revealed a lesion measuring 9 by 6 mm, but tracrolimus serum levels were still elevated. Itraconazole was then discontinued and surgical excision was performed. There has been no recurrence after 1 year of follow-up.

Discussion

Chromomycosis is a rare chronic fungal infection characterized by verrucous and crusted lesions with production of sclerotic bodies in tissue. Most cases occur in tropical and subtropical regions. Recently, an increasing number of cases of chromomycosis are being reported in immunosuppressed patients (organ transplant recipients and other patients treated with immunosuppressive drugs) [8, 12-14].
Organ transplant recipients are highly susceptible to infections caused by oportunistic organisms as a result of their immunosuppressive state. Genera of fungi implicated in cutaneous infections in these patients include Candida, Mucor, Aspergillus, Cryptococcus, Alternaria and Scedosporium. Although Exophiala is the genus of dematiaceous fungi that most frequently cause mycotic cutaneous infections in organ transplant patients [15], an infection clinically presentating as chromomycosis has only been reported in one patient (by Exophiala jeanselmei) [10]. There has been another report describing a similar infection in a patient with rheumatoid arthritis (by Exophiala spinifera) [13].
Exophiala jeanselmei is a dematiaceous fungus which usually causes cystic lesions of cutaneous and subcutaneous phaeohyphomycosis and rarely mycetoma. Chromomycosis due to this mold has been exceptionally reported. We have only found three cases in the literature [9-11] that are summarized in Table I. Two cases of chromomycosis due to Exophiala spinifera have been also published [12, 16], both from USA. To our knowledge, this is the first European case of chromomycosis by Exophiala.

Table I. Cases of chromomycosis caused by Exophiala jeanselmei.

Acknowledgements. The authors thank Dr. Josep Guarro from the Unitat de Microbiología, Facultat de Medicina i Ciències de la Salut in the Universitat Rovira i Virgili, Reus, Tarragona, Spain for confirming the identification of Exophiala jeanselmei and studying the antifungal susceptibility. n

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