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On-line version ISSN 1806-4841
An. Bras. Dermatol. vol.86 no.1 Rio de Janeiro Jan./Feb. 2011
Infections caused by dematiaceous fungi and their anatomoclinical correlations*
Camila de Camargo HoffmannI; Itamara Pereira DanucalovII; Katia Sheylla Malta PurimIII; Flavio Queiroz-TellesIV
IMedical doctor graduated from the Federal University of Paraná - Curitiba (PR), Brasil
IIMedical doctor graduated from the Federal University of Paraná - Internal Medicine resident at the University Hospital from the Federal University of Paraná -Curitiba (PR), Brasil
IIIPhD in Internal Medicine from the Federal University of Paraná - Doctor from the ambulatory of Dermatology from the University Hospital of the Federal University of Paraná - Curitiba (PR), Brasil
IVPHd in Infectious and Parasitic Diseases from the University of São Paulo (USP) - Assistant Professor of Infectology fromthe Federal University of Paraná - Curitiba (PR), Brasil
The Exophiala genus comprises dimorphic melanized fungi responsible for a spectrum of diseases including phaeohyphomycosis, mycetoma, chromoblastomycosis and fungemia. The E. jeanselmei species is predominant in such infections, followed by E. dermatitidis. This paper aims at reporting four cases and at discussing clinical, histologycal, mycologycal and epidemiologycal aspects for its diagnosis.
Keywords: Exophiala; Chromoblastomycosis; Fungi
Dematiaceous fungi are found in nature and one of their characteristics is the presence of melanin, responsible for the dark pigmentation of their spores and conidia and that seems to behave as a virulence factor. More than a hundred species and sixty genera of these fungi are connected to a broad spectrum of human infections.1 The main clinical forms of presentation of the infections through these dematiaceous fungi include phaeohyphomycoses (cutaneous, subcutaneous and systemic), that affect both immunocompetent and immuno-compromised individuals; chromoblastomycosis, mycetoma, sinusitis and bloodstream infections. Among these, chromoblastomycosis and mycetoma are considered occupational diseases.
Clinicopathological studies involving dematiaceous fungi are scarce in medical literature. The recent contributions from Molecular Biology revolutionized the taxonomy of these agents leading to a revision of past diagnosed cases and improving the perspective of present and future diagnoses.3
The authors of this study present four cases of infections caused by species from the genus Exophiala, all of them in farmers from the interior of the state of Paraná, addressing the different clinical, therapeutic and epidemiological aspects as well as the laboratory tests related to these infections
CASE 1 - Male patient, aged 36, Caucasian, with a nodule-cystic lesion well defined, without inflammatory signs, measuring 4,5 cm of diameter in the cavum of the left foot which had started 6 months before with no apparent connection with trauma. He had undergone a renal transplant 4.5 years ago and is currently using prednisone - 15mg /day, cyclosporine350mg/day and azathioprine - 75mg/day. The aspiration of the lesion, of chocolate like staining, presented, when directly examined, pigmented fungal elements: septate hyphae, catenulate and vesicular elements.
The patient had a surgical excision of the cystic lesion that was,- unilocular, with a thick and fibrotic wall, needing a skin graft in the area. The cultivation of secretion originated dematiaceous colonies identified as Exophiala jeanselmei species jeanselmei. The electron microscopy of transmission revealed the presence of great quantities of polymorphonuclear hyphae at different stages of digestion. The electron microscopic scanning of fungus revealed a conidiogenous annelid characteristic of the genus Exophiala (Picture 1). It progressed without recurrence of the lesion.
CASE 2 - Thirty-eight year-old patient, Caucasian, presenting erythematous desquamative plaque and cicatricial lesions on the buttocks which had begun 15 years before and the patient was complaining of pruritus and local pain (Picture 2). For 2 years he underwent two treatments with amphotericin B, with partial response. Histopathological examination showed muriform cells and microabscesses (Picture 3). It was observed the growth of Exophiala jeanselmei in the culture of the lesion. It was suggested treatment with itraconazole but we could not track the patient any further.
CASE 3 - Fifty-nine year-old patient, Caucasian, presenting erythematous desquamative plaque of circinate edges and cicatricial lesions on the lower part of the left leg and foot for 10 years, with pruritus and local pain. This lesion started on the calf after a trauma with fracture of the bone. Skin biopsy revealed muriform cells and granulomatous reaction. It was observed growth of Exophiala sp in the tissue culture. The patient was treated with itraconazole 400mg/ day for 14 months and there was clinical and mycological cure.
CASE 4 - Forty-nine year-old patient, African-Brazilian, presenting edemato-fistulous lesions at his left foot with drainage of black grains and serous secretion (Picture 4). He complained of pruritus and articular pain when walking. The condition had started 33 years before on the toe after a transcutaneous trauma while tilling. For 20 years he was treated with sulfonamides, penicillin and ketoconazole without response. Radiological and functional assessments showed loss of the mobility of the foot; bone and joint lesions extending to tibial diaphysis. The patient underwent amputation of the leg followed by 1 gram of intravenous amphotericin B. Pathology revealed swollen and distorted foot with multiple fistulas transmitting to deep tissue, affecting the bones it also showed granules composed of brown aggregates of swollen cells and rare hyphae, with 80 µm, without intercellular substance. Around the grains there was a granulomatous tissue with multinucleate histiocytes and neutrophilic exudate (Picture 5). Direct microscopy showed grains presenting smooth texture with characteristics similar to the fixed material. In the Sabouraud's dextrose agar medium the grains collected from the surgical specimen gave growth to black colonies that later were covered with gray mycelium. The fungus was identified as Exophiala jeanselmei.
Infections caused by dematiaceous fungi have a great variety of clinical manifestations, represented clinically on the skin as phaeohyphomycosis, chromoblastomycosis and eumycotic mycetoma. Allergic diseases may occur such as fungal sinusites apart from pneumonia and lung abscess.1 The disease tends to be systemic2 in immuno-compromised patients, mainly with cellular immunodeficiency.
The genus Exophiala is composed of dimorphic fungi. The yeast colonies are of brown or black color and dry aspect4. Optical microscopy showed dark yest cells, septate and branched hyphae or hyphae formed by chains of spherical cells (moniliform or muriform hyphae) with abundant buds and annelid conidiogenesis, unicellular, rarely septate, hyaline or dark.5
The cases reported are cases of chronic fungal diseases with prolonged evolution and incubation period, prevalent in men around 30-40 years of age7. They were farmers that presented risk factors for the traumatic inoculation of these fungi. The immunosuppression condition verified in one of them that develops fungal infection and its occurrence is increasing due to a increasing population of patients with secondary immune deficiency.2 These epidemiological data are in accordance with the medical literature. The clinical presentation of the disease, in our patients, was classic and considered as: a nodule-cystic lesion without signs of inflammation in phaeohyphomyco-sis5(Case 1), plaques in chromoblastomycosis 6(cases 2 and 3) and fistulas with grain drainage in eumycetoma (Case 4). 8
Case 1 reports a post renal transplantation patient using immunosupressive drugs who developed phaeohyphomycosis. Sabbaga et al describe four patients who had had a renal transplantation and developed phaeohyphomycosis caused by Exophiala jeanselmei and who had had good results after surgical excision, as our patient.9 Silva et al present a similar case also caused by E.jeanselmei: a patient after cardiac transplantation with similar results.10
Cases 2 and 3 portray the classic patients affected by chromoblastotomycosis, farmers, presenting chronic lesions on the limbs11, with a history of previous trauma in one of the cases.12
Case 4 is a characteristic case of a eumycetoma infection, a patient from the countryside that after transcutaneous trauma developed fistulae formation with grains drainage. Bone invasion suggests an advanced disease, refractory to inadequate therapeutics that had been used for 20 years, progressing to limb amputation.8
The final diagnosis of the diseases caused by any of the species of cutaneous and subcutaneous fungi should be made through culture of the biopsied materials.1 These procedures, carried out in our patients, confirmed the diagnosis with the development of the Exophiala fungus. This microorganism, usually of low virulence, presents itself clinically and of importance when the host is exposed to its risk factor, in the cases decribed, the inoculation and the immunosuppression. Three patients had results of culture with Exophiala jeanselmei, while the fourth had Exophiala sp, coinciding with the literature that cites Exophiala jeanselmei as the dominant species followed by E. dermatitidis.5
Subjects in the treatment which was carried out was consistent with other authors. As for phaehyphomycosis, surgical excision is the most frequent procedure and it was carried out with success, without evidence of recurrence.6 As for chromoblastomycosis, in the third case was treated with itraconazole, drug from the group of azoles that in vitro proved to have excellent activity against dematiaceous1. this being one of the drugs of choice for the treatment of this type of infection. The patient with mycetoma underwent a left lower limb amputation due to the refractoriness of the case to the medications used, a common fact concerning mycetomas.
The analysis of these cases shows us that the clinical aspect of the infections caused by dematiaceous, in special from the Exophiala genus, is broad and recquires different procedures. The members of this genus is present in vitro and has a high degree of phenotypic plasticity as the fragment of tissue from skin lesions is rarely cultivated.
Early diagnosis is primordial despite the chronicity and long evolution of these diseases. Its infiltrative feature is capable of leading to sequelae and amputations. There is no consensus yet regarding the treatment of subcutaneous fungal diseases and there are few clinical trials comparing different drugs. On the other hand, research indicates practicality in the in vitro susceptibility test of each causal agent with certain drugs13 that would provide a more targeted and effective treatment. It is noteworthy that educational measures in health are important to minimize the damage and injuries of such infections.
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Received on 15.09.2009. *
Work conduced at Infectology Service from the University Hospital of the Federal
University of Paraná - Curitiba (PR), Brasil.
Approved by the Advisory Board and accepted for publication on 21.12.10.
Conflict of interest: None
Financial funding: None
Received on 15.09.2009.
* Work conduced at Infectology Service from the University Hospital of the Federal University of Paraná - Curitiba (PR), Brasil.