Severe Pneumocystis jirovecii Pneumonia Revealing an Underlying Telomere Maintenance Defect: A Clinical Case Study

Pneumocystis jirovecii pneumonia (PJP) is typically associated with immunocompromised states, yet its occurrence as the initial manifestation of an underlying genetic disorder remains uncommon. This case study describes a patient presenting with severe PJP who was subsequently diagnosed with a telomere maintenance defect. The patient exhibited progressive respiratory distress, hypoxemia, and diffuse interstitial infiltrates on imaging. Initial management included antimicrobial therapy targeting Pneumocystis jirovecii , alongside supportive respiratory care. Despite standard treatment, the clinical course was complicated, prompting further investigation into potential underlying immunodeficiency. Advanced genetic testing revealed abnormalities in telomere-associated genes, confirming a telomere biology disorder. This finding provided a unifying explanation for the patient’s susceptibility to opportunistic infection and highlighted the role of impaired cellular senescence and immune dysfunction in disease progression. The case underscores the importance of considering inherited telomere disorders in patients with atypical or severe presentations of opportunistic infections, particularly in the absence of classical risk factors. Early recognition of such conditions is essential for guiding long-term management, genetic counseling, and surveillance for associated complications, including bone marrow failure and pulmonary fibrosis. This report contributes to the growing body of evidence linking telomere dysfunction with infectious vulnerability and emphasizes the need for a multidisciplinary diagnostic approach.