Phaeohyphomycoses in Lung Transplant Recipient

Abstract

<h3>Introduction</h3> Phaeohyphomycoses are fungal infections caused by dematiaceous fungi, mold with dark colored walls due to the presence of melanin, which are found in soil around the world. The melanin acts as a virulent factor contributing to pathogenesis. Despite ubiquity of these organisms and more than 100 causative species known, infection remains rare with increased frequency noted in solid organ transplant recipients (SOTR) due to immunosuppression and their opportunistic nature. The spectrum of disease is wide, ranging from localized skin/soft tissue infection to disseminated disease with high mortality. <h3>Case Report</h3> A 34 year old male with occupational lung disease requiring bilateral lung transplant 1 year prior, on a standard immunosuppressive regimen with no previous augmentation, presented with small, non-erythematous nodules on his right arm (RUE) and lower leg (RLL). Lesions were painful initially at onset 6 months ago; the tenderness resolved but the nodules persisted and enlarged in size with associated development of new onset dyspnea. Imaging revealed mild scattered ground glass opacities with right lower lobe bronchial wall thickening. Bronchoalveolar lavage fungal culture grew Bipolaris spp. RUE nodule punch biopsy was obtained with septate hyphae on KOH prep and Phialemonium spp. on culture. Excisional biopsy of both nodules revealed seropurulent drainage grossly and invasive filamentous fungal forms on pathology. KOH prep of both again demonstrated septate hyphae, with Phialemonium spp. from RUE and Colletotrichum spp. from RLE. There were no signs of hematogenous spread. He was started on a prolonged course of posaconazole and temporary decrease in immunosuppression with clinical improvement and no return of nodules after excision. <h3>Summary</h3> Phaeohyphomycoses remain rare though occur with increased incidence in SOTR. Here we present a case of multifocal, but not disseminated, phaeohyphomycoses caused by 3 distinct dematiaceous fungi in a lung transplant recipient and avid gardener. Diagnosis occurs histologically and microbiologically in setting of high clinical suspicion. We suspect inhalation and two separate instances of direct inoculation during time spent gardening resulting in concomitant pneumonia and subcutaneous infection by multiple causative dematiaceous fungi. Infection at non-contiguous sites presented as diagnostically challenging with social history as key.