Eumycetoma due to Parathyridaria percutânea in an immunosuppressed patient - an imported case in Portugal

Fraga, Marta; Carvalho, Dinah; Sabino, Raquel; Veríssimo, Cristina; Simões, Helena; Sapinho, Guilherme; Alho, Ana; Espada, Eduardo; Moreno, Raul; Forjaz de Lacerda, J.; Marques Lito, L.; Melo Cristino, J.

http://hdl.handle.net/10400.18/8092

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Authors

Forjaz de Lacerda, J.

Abstract(s)

Objectives: Eumycetoma is a chronic subcutaneous fungal infection characterized by swelling, fistulization and discharge of fungal granules. These infections occur after traumatic inoculation and progress slowly over months or even years into a chronic form. Parathyridaria percutanea is a rare cause of subcutaneous phaeohyphomycoses and there are no published reports of discharging sinus or granuloma formation due to this fungus. We present a rare case of eumycetoma due to Parathyridaria percutanea in a 10-years-old patient from Angola, presenting after allogeneic hematopoietic stem cell transplant (alloHSCT) for severe aplastic anemia. Material and methods: A 10-year-old boy from Angola with severe aplastic anemia was transferred to Portugal and submitted to alloHSCT from a mismatched unrelated donor at a single HLA-locus (9/10). After secondary graft failure due to post-transplant hemophagocytic lymphohistiocytosis, he underwent a second alloHSCT, without engraftment. Twenty-three days after the 3rd alloHSCT from the same donor and seven days under prophylaxis with posaconazole, the patient presented with febrile neutropenia with no clear focus. He complained of painless swelling of the right knee, with slight fluctuation. An ultrasound was performed revealing a heterogeneous hypoechogenic area with imprecise contours, inside of which there was a nodular formation of approximately 10 mm. Two weeks later, a spontaneous drainage of a grossly spherical grain from the right knee occurred. It was characterized as extra-articular, subcutaneous with filamentous aspect. The material was sent to the laboratory where its macroscopic observation allowed the identification of a granule of possible mycotic etiology, consistent with the diagnosis of eumycetoma. This sample was promptly processed for bacteriology (aerobic and anaerobic) and mycology studies. Results: Direct microscopic examination of the grain revealed septate hyphae with irregular hyphal swellings. Cultures for bacteria (aerobic and anaerobic) were sterile. After 1 week, slow growing colonies appeared on Sabouraud dextrose agar (SDA) incubated at 25 °C. Those colonies were flat, spreading with sparse aerial hyphae, become creamy after 5 to 10 days and with orange reverse and then turned dark brown after 4 weeks. Lactophenol cotton blue mount revealed nonsporulating dematiceous hyphae with clamidospores. Phenotypic identification of the organism was uncertain but sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA identified as Parathyridaria percutanea (100% homology, 99% coverage). The isolate showed in vitro resistance to itraconazole, fluconazole and anidulofungin and susceptibility to posaconazole, voriconazole and amphotericin B. As this pathogen is extremely rare, no antifungal guidelines have been proposed so far. The patient received dual coverage with posaconazole and liposomal amphotericin-B but died 2 weeks later of complications of the underlying disease. Conclusions: The presented case maybe the first described case of eumycetoma caused by Parathyridaria percutanea associated with fistulae presentation. Molecular identification of rare fungi is essential, especially when they are poorly sporulated, as in this case. Moreover, rare fungi can present with odd clinical signs, as in this case, emphasizing the relevance of a polyphasic approach to identify the etiological agent.