<i>Schizophyllum</i> <i>commune</i> infection following chimeric antigen receptor T-cell therapy in a patient with lymphoma

Infectious complications are common following chimeric antigen receptor (CAR) T-cell therapy for B-cell lymphoma due to its prolonged immunosuppressive effects. Schizophyllum commune is an exceedingly rare fungal pathogen that typically affects the respiratory tract and may mimic chronic pulmonary aspergillosis. Infections caused by S. commune have been primarily reported in recipients of allogeneic hematopoietic stem cell transplantation. Here, we report the first known case of S. commune infection in a patient treated with CAR T-cell therapy. A 71-year-old woman with primary refractory large B-cell lymphoma received lisocabtagene maraleucel as second-line therapy. Six months post-treatment, computed tomography revealed right middle lobe atelectasis with high-attenuation mucus. Bronchoscopic biopsy, fungal culture, and internal transcribed spacer gene region sequencing confirmed the diagnosis of S. commune infection presenting as allergic bronchopulmonary mycosis (ABPM). Notably, serologic tests were negative for fungus-specific specific immunoglobulin G and immunoglobulin E. The patient responded favorably to 4 months of oral voriconazole therapy, with resolution of symptoms and radiologic findings. This case highlights the potential for rare fungal infections, such as S. commune, to occur following CAR T-cell therapy. Although the clinical and radiologic features were consistent with ABPM, the absence of serologic markers underscores the diagnostic challenges posed by B-cell aplasia resulting from B-cell-directed immunotherapy.