This patient present with sudden onset of chest pain, with the initial chest x-ray demonstrating a right hydropneumothorax. A right intercostal catheter was inserted with approximately 1 L of fresh blood draining initially with another liter draining over the next 2 hours. 

CTA demonstrated active bleeding in the upper intercostal region with this confirmed on DSA with subsequent successful embolization. 

No cause was identified with no proceeding trauma or infection, and no past medical history. No mass or vascular malformation identified on imaging.

Spontaneous hemopneumothorax is rare, with a few mechanisms proposed ^1,2:

• torn adhesion between the parietal and visceral pleura after a spontaneous pneumothorax
• rupture of a bulla resulting in damage to underlying vascularized lung parenchyma​