An unexpected and unusual cause of pulmonary hypertension in a patient with hypersensitivity pneumonitis: a partial anomalous pulmonary venous connection causing pulmonary artery hypertension.

Partial anomalous pulmonary venous connection (PAPVC) occurs when any pulmonary vein, but not all, drains directly into the right atrium or its venous tributaries. PAPVC can very rarely present as an individual cause of pulmonary artery hypertension. Here we are presenting the case of a 41-year-old farmer with a history of exertional dyspnea for the past 3 years, which increased over 6 months. Chest high-resolution computed tomography was suggestive of non-fibrotic hypersensitivity pneumonitis. Hence, the patient was started on systemic steroids, with which the patient's oxygen saturation improved. On 2D echocardiography, the right ventricle systolic pressure was 48 + right atrial pressure. Right heart catheterization showed a mean pulmonary artery pressure of 73 mmHg and pulmonary vascular resistance of 8.7. On further evaluation, a computed tomography pulmonary angiogram was done, which surprisingly revealed the left superior pulmonary vein draining into the left brachiocephalic vein.