Exophiala spp. isolated from lung biopsy of a woman with chronic lymphocytic leukemia

Pinheiro1, M.D., Principe2, F., Roncon2, R.

Author address: 

1 Laboratory of Microbiology, HS João, PORTO, Portugal 2Service of Clinical Haemathology, HSJoão, PORTO, Portugal

Abstract: 

Exophiala spp., a dark yeast-like fungus, belongs to the Dematiaceous, a heterogeneous group of fungi sharing dark pigmentation as a unifying feature. This pigmentation is due to the presence of dihydroxynaphthalene melanin in the cell walls of hyphae or conidia or both. These species are found in the environment and were reported in wild animals too. They are pleomorphic and their identification by means of biochemical testing is frequently controversial due to significant intraspecies variation. For that reason, currently, it is recommended that their identification should be based on molecular genetics techniques. Here we report the isolation of an Exophiala spp. in the culture of the biopsy of a lung nodule from a Caucasian woman, 66 years old, with the diagnosis of Chronic Lymphocytic Leukemia (CLL) for over five years. She was healthy until January 2001, when she noticed weight loss and weakness, just before the diagnosis of CLL, RAI I stage, was established. The disease kept stable until January 2004, when it was necessary to start chemotherapy with fludarabine; in December 2004 the disease was progressing, which led to cyclophosphamide, vincristine and prednisone (CVP) treatment in April 2005. In January 2006, she had another chemotherapy cycle adding rituximab/antiCD20 (R-CVP). There was a partial clinical improvement in July 2006 which led to the discontinuation of the therapy. At that time, she began treatment with voriconazole because of a presumed pulmonary fungal infection. The lack of improvement in the clinical condition of the patient and the appearance of a diffuse micronodular pattern in the pulmonary CT scan, were the reason for a guided biopsy in November 2006. Samples of the biopsy were sent to the microbiology laboratory to culture on blood-, chocolate- and MacConkey-agar at 35 ºC for bacteria and on Sabouraud-chloramphenicol-gentamicin media at 25ºC, for yeasts. While bacterial cultures were negative, on the Sabouraud media appeared peculiar, small, dark, yeast-like colonies at the 7th day. They enlarged in the following days and at the 10th the microscopical observation of the fungus suggested that it was a Exophiala spp.. The molecular identification of the species is in progress. The patient started posaconazole 400mg PO bid from December 2006 onwards. Presently, due to the progress of the CLL, the patient is also receiving cyclophosphamide and prednisone. The CAT images are similar to the previous ones, but on the cultures of BAL samples, April 2007, there was no microbial growth. This is the first time a black yeast-like fungus is isolated in our laboratory. Apart from the immunocompromised condition of the patient, the personal history did not disclose particular features, except the fact that the patient used to ride and deal with earth frequently. This case emphasizes the importance of sending to the laboratory all the samples of immunodepressed patients and performing mycological studies, since more and more unusual fungi are being isolated from them.
2007

abstract No: 

P187

Full conference title: 

3rd Trends in Medical Mycology
    • TIMM 3rd (2011)