In general, patients with active cGvHD taking immunosuppressive treatment (especially multimodal treatment including steroids) and/or with neutropenia and/or with CD4+ T cells <200 × 109/L may be at risk of Pneumocystis jirovecii infection, taking into account that the initially HIV-derived CD4+ T-cell threshold has been not evaluated in the cGvHD setting and Pneumocystis jirovecii infections have been observed in patients above the proposed threshold. This evidence concerns the gene CD4 and neutropenia.