A Rare Case of Symmetrical Cutaneous Alternaria Infections after Bilateral Lung Transplant

Abstract

Introduction Lung transplant recipients are prone to opportunistic infections like fungi in view of the high levels of sustained immunosuppression required to avoid graft rejection. We report an unusual fungal pathogen, Alternaria, presenting with bilateral, cutaneous lesions with an atypical morphology. Case Report A 73-year-old male underwent bilateral lung transplantation in October 2017 for idiopathic pulmonary fibrosis with basiliximab induction. The patient was on typical three-drug immunosuppression of tacrolimus (goal trough 7-8ng/ml), prednisone, and mycophenolate mofetil (lower dose 250mg bid). At his one year follow up, he was noted to have symmetrical, keratotic lesions on both lower extremities. The patient reported no traumatic source, except for fire ant bites or minor scratches while gardening. Punch biopsies were performed and histopathology revealed epidermal hyperplasia with associated underlying granulomatous host response. After assessing morphology and Fontana masson stain, a differential of Blastomyces species was favored over Cryptococcus. However, serum tests were negative for Blastomyces and fungal cultures from the biopsy grew Alternaria. Given non-contiguous sites and concern for dissemination, a chest CT was performed, but did not note changes consistent with pulmonary involvement. He was treated with posaconazole (300mg daily) for a 3-month regimen with a decrease of tacrolimus levels. With noted regression of nodules after three months, posaconazole was stopped. A year later, a recurrence of Alternaria appeared on his lower extremities, distal to the previous infections, with the same raised violaceous appearance. Treatment with posaconazole (200mg daily) was initiated. Due to recurrence, mycophenolate was halted and serum tacrolimus levels were targeted lower. After 6 months, posaconazole was stopped as the lesions had healed. Summary Our path to diagnosis in this case highlights the challenges in confirming infectious species by histopathology alone and hence the importance of culture and molecular diagnosis. This case was particularly unusual with the presentation of symmetrical lower extremity lesions as it was not clear if this represented dual inoculation or a disseminated infection. A high level of suspicion needs to be maintained for lesser known fungal pathogens, like Alternaria, in highly immunocompromised hosts.