Pneumonia in a Post-Transplant Patient: The Eosinophilic Red Herring

Introduction: Pneumonia remains a significant infectious complication post-kidney transplant with poor outcomes, such as mechanical ventilation, worsening graft function, and higher mortality. Fungal etiology has been reported as the underlying cause in 20-30% of cases. We present a case of Pneumocystis (PJP) Pneumonia masquerading as eosinophilic pneumonia. Case Description: A 47-year-old female with kidney failure due to Goodpasture syndrome, status post deceased donor kidney transplant in 2014, maintained on tacrolimus and mycophenolate mofetil (MMF) presented with two weeks of fatigue, shortness of breath, and intermittent fevers. She reported exposure to mouse droppings while cleaning and vacuuming an old house for a week. She was found to have acute kidney injury (AKI) with a creatinine of 2.7 mg/dl (up from a baseline of 2 mg/dl). Chest x-ray showed bilateral mid to lower lung zone airspace opacification with septal thickening, and CT chest showed diffuse ground glass opacities with areas of mosaicism. She was started on empiric broad-spectrum antibiotics. Extensive infectious workup remained unyielding, except for a beta-D-glucan level of >500, following which voriconazole was added. She became progressively hypoxic and septic, needing mechanical ventilation and pressors. Immunosuppression was withheld. Bronchoalveolar lavage revealed 20% eosinophils, cytology and special stains were negative for any viral cytopathic changes or fungi. Steroids were started for presumed eosinophilic pneumonia, and trimethoprim-sulfamethoxazole was added simultaneously to cover Pneumocystis Pneumonia (PJP), toxoplasma, and nocardia. Plasma microbial cell-free deoxyribonucleic acid (mcfDNA) was sent, which resulted positive for PJP (17,328 copies per 100 nL). She was managed with Atovaquone for 3 weeks. Her renal function eventually improved, and immunosuppression was resumed thereafter. Discussion: Pneumocystis pneumonia is a dreaded complication in transplant patients with a mortality of up to 20% in severe cases. Diagnosis is challenging given a nonspecific clinical presentation and imaging findings, and difficulty in culturing the organism on biological specimens. mcfDNA sequencing has improved sensitivity and specificity and favorably impacted the management of PJP Pneumonia. It remains an important differential for eosinophilic pneumonia.