This 4 week old girl presented with persistent pulmonary hypertension. She decompensated acutely due to influenza A infection.

Once the infection resolved there was persistent interlobular septal thickening consistent with an interstitial process. There were also persistent pleural effusions. These features were suggestive of lymphangiectasia.

Wedge biopsy confirmed lymphangiectasia. The effusions were not chylous and this was thought to be because in this child the lymphangiectasia was secondary to obstructed pulmonary venous return.

The narrowing of the left pulmonary vein may be part of this same process.