ICL is a rare condition defined as a CD4+ T-cell count of <300 cells mm–3 or <20% of total lymphocytes measured at least 6 weeks apart in the absence of disease or treatment associated with immunodeficiency.4 This patient was initially diagnosed with ICL by the infectious diseases team, when he presented with presumptive Pneumocystis jirovecii pneumonia. This evidence concerns the gene CD4 and pneumocystosis.