De Novo Pneumocystis jirovecii Pneumonia as the Initial Manifestation of Short Telomere Syndrome: A Case Report

Short telomere syndromes are inherited disorders characterized by premature cellular aging, impaired tissue regeneration, and susceptibility to bone marrow failure, pulmonary fibrosis, and immune dysfunction. Although infectious complications are recognized in advanced disease, opportunistic infections as the initial clinical presentation remain uncommon. This case report describes a patient who developed de novo Pneumocystis jirovecii pneumonia (PJP) as the first manifestation of an underlying short telomere syndrome. The patient presented with progressive dyspnea, nonproductive cough, and hypoxemia, without a prior history of immunosuppression or chronic lung disease. Radiologic findings demonstrated bilateral ground-glass opacities, and microbiological analysis confirmed Pneumocystis jirovecii infection. Further evaluation, prompted by unexplained cytopenias and clinical suspicion, revealed critically shortened telomere length consistent with a telomere biology disorder. The patient responded to targeted antimicrobial therapy, alongside supportive care, but required long-term monitoring for multisystem complications. This case underscores the importance of considering inherited telomere disorders in patients presenting with atypical or unexplained opportunistic infections, even in the absence of known immunodeficiency. Early recognition is essential for appropriate management, genetic counseling, and risk stratification, particularly in preventing disease progression and guiding transplant-related decisions. The report contributes to the growing body of evidence linking telomere dysfunction with impaired host defense and highlights the need for heightened clinical awareness in similar presentations.