Disseminated Cryptococcus Neoformans Infection in a Renal Transplant Patient

Background: Cryptoccocus Neoformans is a fungus mainly found in the environment that infects humans via inhalation and usually affects the lungs and central nervous system. Most people remain asymptomatic; however, immunocompromised patients are most susceptible to this pathogen, particularly HIV/AIDs patients. We present a case of a renal transplant patient with disseminated Cryptococcus Neoformans infection. Case Presentation: A 71 y/o female presents to the emergency department for further evaluation of a fever of unknown origin that has been going on for 6 days. Outpatient workup was initiated by the transplant service; however, due to persistently high fevers she was admitted for further workup and management. Patient reports that her fevers mainly occur at night and reach a maximum of 104-105 F. In the morning the fever decreases to 102 F with Tylenol. Denies any other significant symptoms, recent travel, sick contacts, alcohol, tobacco, or drug use. Past history is significant for CKD due to IgA nephropathy with renal transplant 2.5 years ago. Patient is currently on a chronic immunosuppressive regimen of Mycophenolate and Tacrolimus and infection prophylaxis with TMP-SMX and Valganciclovir. Upon admission, vitals were within normal limits and physical exam was unremarkable. Labs showed negative urinalysis, influenza, COVID-19, and rapid strep antigen test. Lactic acid, magnesium, coagulation studies, TSH, and troponin were all within normal limits. BUN was elevated at 32 and Creatinine at 1.8. White blood cell count was decreased at 2.8k, hemoglobin decreased at 10.9, and hematocrit decreased at 34.2. Chest X-ray showed nodular opacifications involving the right mid to upper lung, possibly masses or mass like infiltrates. Malignancy at this point was high on the differential. CT of the chest was then obtained, which revealed a right upper lobe mass and bilateral pulmonary lymph node involvement that was concerning for metastatic disease. On admission day 2, a CT guided lung biopsy was done. Preliminary reads were suggestive of fungal etiology and no malignancy with the final report of histoplasmosis, but clinical correlation was recommended. On day 5, Cryptococcus Antigen (Ag) titer was obtained and was elevated. On day 6, bronchoscopy with cultures using MALDI-TOF revealed Cryptococcus neoformans and no malignant cells. Given concomitant cytopenia, patient was started on treatment for disseminated Cryptococcal disease with ambisome and flucytosine. However, patient developed an AKI likely from ambisone, and the regimen was switched to PO Voriconazole BID. On day 10, patient was switched to high dose fluconazole. On day 12, repeat Cryptococcal Ag titers showed an increase from 1:40 to 1:320, which was concerning for a high fungal burden. Ambisone was added back on with the fluconazole; however, due to worsening renal function ambisome was held again. Ultimately, the patient wanted to go home and she was discharged on high dose fluconazole per infectious disease recommendation with PCP and transplant service outpatient follow up. Discussion: This case demonstrates that although lobar masses in the elderly can be highly suspicious for malignancy, rarer causes such as Cryptococcus Neoformans should be considered on the differential.