Pneumocystis Jirovecii Pneumonia Associated with Prolonged CD4-positive T-cell Depletion after Bendamustine-Rituximab Therapy: A Case Report.

A 71-year-old man with Waldenström's macroglobulinemia developed probable Pneumocystis jirovecii pneumonia (PCP) 10 months after completing bendamustine-rituximab (BR) therapy and 7 months after discontinuing trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis. His CD4-positive T-cell count was 37 cells/μL, and no other apparent risk factors, including human immunodeficiency virus infection, were identified. While his condition improved with TMP-SMX, his CD4-positive T-cell count had only recovered to 183 cells/μL by 18 months after completing BR therapy. This case suggests that prolonged CD4-positive T-cell depletion after BR therapy may contribute to late-onset PCP and it highlights the importance of an individualized assessment of immune recovery and PCP prophylaxis.