Fatal Pulmonary Mucormycosis in a Kidney Transplant Patient: Missed "Opportunism"

Introduction: Pulmonary mucormycosis (PM) has a high mortality rate if not diagnosed promptly. We present a fatal case in a patient presenting seven months post-transplantation whose diagnosis was delayed, and emphasize the need for early diagnosis of opportunistic infections. Case Description: A 55-year-old man with ESRD and prior failed deceased donor kidney transplant (DDKT) underwent a second DDKT complicated by delayed graft function and antibody-mediated rejection treated with apheresis and IVIG. Seven months post-transplant, he presented with cough, fever, diarrhea, and weight loss. He was on tacrolimus, mycophenolic acid, and prednisone. Imaging revealed diverticulitis and a cavitating thick-walled right lower lung lesion. He was treated with ampicillin/sulbactam but had continued fevers and respiratory distress. Serologic infectious workup was unrevealing; galactomannan test was negative. Bronchoalveolar lavage on hospital day 4 identified Streptococcus species; piperacillin/tazobactam was given for seven days. The patient worsened and required noninvasive ventilation. Repeat imaging demonstrated a pleural effusion with invasion of the RLL mass into the right middle lobe, diaphragm, and liver. Thoracentesis was performed on hospital day 12 and a lung biopsy on day 19. Pleural fluid and tissue histology was consistent with mucor. Amphotericin was started and he was transferred for surgical debridement, but died within 24 hours. Discussion: Kidney transplant patients are immunosuppressed and at risk for opportunistic infections. Mucormycosis accounts for 2-6% of fungal infections and emerges usually after 6 months post-transplantation as rhinocerebral, PM, skin, or disseminated disease. Concomitant bacterial pneumonia occurs in 30% of PM cases. A negative galactomannan test is expected as mucor lacks this cell wall antigen. Reverse halo sign on imaging is suggestive but histology is necessary for diagnosis. The presence of characteristic non-septate, right-angled branching hyphae confirms diagnosis. Treatment requires intravenous liposomal Amphotericin B and surgical debridement. PM is rapidly progressive, invasive, and carries a 60-70% mortality rate. This case highlights the pitfalls of empiric approaches to infections in immunocompromised hosts and the need for early suspicion for opportunistic infection and tissue diagnosis to optimize outcomes.