Vasoreactive pulmonary artery hypertension in non-fibrotic hypersensitive pneumonitis.

Group III pulmonary hypertension (PH) is common in patients with hypersensitivity pneumonitis (HSP). Group I PH and vasoreactivity in HSP have not been reported. We describe a case of an elderly veterinarian woman who presented with progressive shortness of breath and desaturation on exertion. The patient was diagnosed with non-fibrotic HSP after consistent findings on chest CT, transbronchial biopsy and a positive HSP serological panel. The patient relocated her birds, and prednisone was started. Due to persistent symptoms, she underwent a right heart catheterisation, which showed PH with vasoreactivity; subsequently, nifedipine was started. Over a 9-month follow-up, there was an improvement in symptoms and a complete resolution of PH and CT scan changes. Our case highlights the rare possibility of group I PH in HSP. It illustrates the importance of confirming the aetiology of PH and initiating treatment early to resolve symptoms.