[Dyspnea, pulmonary mosaic sign and pulmonary hypertension].

This case report presents a young female patient whose chief complaint was exertional dyspnea. Right heart catheterization confirmed severe pulmonary hypertension. Concurrently, chest CT showed atypical pulmonary parenchymal and interstitial lesions, and pulmonary function tests indicated severe impairment of diffusion capacity. To clarify whether an association existed between the lung disease and pulmonary hypertension, transbronchial lung cryobiopsy was performed, which revealed multinucleated giant cell aggregates within the alveolar spaces, with cholesterol clefts in the cytoplasm of some of them. Together with a 1-year history of pigeon exposure, the final pulmonary diagnosis was extrinsic allergic alveolitis (hypersensitivity pneumonitis).With respect to the pulmonary hypertension, genetic testing showed no significant abnormalities, thereby ruling out heritable pulmonary hypertension. After oral imatinib combined with macitentan was administered, the patient's pulmonary artery pressure gradually decreased and her symptoms recovered well; however, follow-up chest CT and pulmonary function tests showed no apparent improvement. Because the elevated pulmonary artery pressure was inconsistent with the pulmonary disease, the patient was ultimately diagnosed with idiopathic pulmonary hypertension complicated by allergic alveolitis.