Severe Occupational Hypersensitivity Pneumonitis: A Case Series of Four Patients Requiring Lung Transplantation.

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease triggered by repeated inhalation of organic or chemical antigens. Occupational exposures account for approximately 19% of all cases. Early diagnosis, identification of the responsible antigen(s), and immediate avoidance of exposure are crucial to prevent irreversible pulmonary fibrosis. However, HP often remains unrecognized or is misclassified as another respiratory disorder such as asthma, chronic obstructive pulmonary disease (COPD), or idiopathic pulmonary fibrosis. As a result, the causal link between symptoms and workplace exposure is frequently established only in advanced disease stages-or not at all. Such delays may result in chronic respiratory failure, occupational disability, prolonged oxygen therapy, and, in severe cases, lung transplantation. We report four patients in whom HP was ultimately recognized as an occupational disease or recommended for legal recognition in court. At the time of diagnosis, all cases had progressed to advanced, fibrotic HP, rendering both primary and secondary prevention impossible. In each instance, earlier identification of the occupational trigger followed by immediate antigen avoidance could likely have prevented the development of irreversible lung damage. This case series underscores the need for early and comprehensive pulmonary assessment, including detailed occupational history-taking, serologic and radiologic evaluation, and prompt referral to an occupational physician when HP is suspected. Close interdisciplinary collaboration between pulmonologists and occupational medicine specialists is essential to reduce diagnostic latency, prevent progression to end-stage lung disease, and improve clinical and socioeconomic outcomes.