Pneumocystis jirovecii infection in autologous hematopoietic stem cell transplantation.

Pneumocystis jirovecii pneumonia (PJP) after autologous stem cell transplantation (ASCT) remains insufficiently characterized. We retrospectively analyzed 304 ASCT recipients (2005-2024) at a single center (B-cell lymphoma n = 138; plasma cell tumor n = 126). Fourteen patients (4.6%) developed PJP at a median of 143 days (86-286) post-ASCT; none were on prophylaxis at diagnosis. The 1-year cumulative incidence was 5.2% overall, and varied by disease: 24% in follicular lymphoma (FL), 5.9% in other B-cell lymphomas, 1.9% in plasma cell tumor, and 0% in T-cell lymphomas. Prior rituximab exposure (HR 6.75; 95% CI 1.50-30.2) and FL diagnosis (HR 7.26; 95% CI 2.51-20.9) were associated with higher risk; age, purine analogs, lymphocyte count, globulin/IgG, and conditioning were not. No death was directly attributable to PJP. These data suggest, diagnosis-dependent risk after ASCT; prophylaxis may be considered for rituximab-treated patients, especially FL, while the optimal duration warrants further study.