Opportunistic Fungal Pneumonia Leading to the Diagnosis of a Telomere Biology Disorder: Clinical Features and Diagnostic Challenges

Telomere biology disorders (TBDs) are a heterogeneous group of inherited conditions characterized by defective telomere maintenance, leading to premature cellular senescence and multisystem involvement. Although pulmonary fibrosis and bone marrow failure are well-recognized manifestations, infectious presentations may be the first clinical clue, particularly in individuals with unrecognized immunologic impairment. We report a case of opportunistic fungal pneumonia that prompted the diagnosis of an underlying TBD, highlighting the diagnostic complexity and clinical implications. A previously healthy adult presented with progressive dyspnea, nonproductive cough, and hypoxemia. Radiologic evaluation demonstrated diffuse bilateral ground-glass opacities, raising suspicion for opportunistic infection. Microbiological investigations confirmed fungal pneumonia, while laboratory studies revealed cytopenias and subtle immunodeficiency. Given the atypical severity of infection in the absence of known risk factors, further evaluation was undertaken. Telomere length analysis demonstrated critically shortened telomeres, and genetic testing identified a pathogenic variant consistent with a telomere biology disorder. This case underscores the importance of considering underlying genetic and immunologic conditions in patients presenting with severe or unusual infections. Opportunistic fungal pneumonia may serve as an initial manifestation of TBDs, particularly in adults lacking classic phenotypic features. Early recognition is crucial, as it influences management strategies, including infection prophylaxis, avoidance of toxic therapies, and consideration of hematopoietic stem cell transplantation. In conclusion, clinicians should maintain a high index of suspicion for telomere-related disorders in patients with unexplained opportunistic infections and hematologic abnormalities. A multidisciplinary approach integrating clinical, radiologic, and genetic data is essential for timely diagnosis and improved patient outcomes.