Hydropneumothorax – Rare presentation of pulmonary embolism with methylenetetrahydrofolate reductase mutation with hyperhomocysteinemia

Pulmonary embolism (PE) is a relatively common cardiovascular event with high early mortality rates. Many risk factors play a role in the causation of PE including acquired as well as inherited. Methylenetetrahydrofolate reductase (MTHFR) gene mutation is one of the inherited etiologies for PE which cause hyperhomocysteinemia which can lead to PE. This in turn can result in secondary complications such as pneumothorax or hydropneumothorax, which are rare presentations of PE. Hereby, we present this unique case of a 17-year-old boy who presented with a hydropneumothorax which on further evaluation was found to be a complication of bilateral PE which was due to hyperhomocysteinemia with MTHFR A1298C mutation. Hence, we present this unique case with rare presentation as well as rare etiology for PE. This shows the significance for considering PE as one of the differentials in situations such as cavitations, pneumo or hydropneumothoraces, and hyperhomocysteinemias.