Pneumothorax resulting from traumatic thoracic injury is a potentially life-threatening emergency requiring prompt recognition and management with an intercostal drain. A 34-year-old woman was brought into the emergency department after sustaining a stab injury to the right upper outer quadrant of the right breast. She described noticing a jelly-like substance from her wound, on the background of a prior cosmetic breast augmentation. On examination, it was noted that the right breast was significantly swollen. Computed tomography demonstrated a large right sided pneumothorax with associated punctured right breast implant, a ‘pneumocapsule’ and extensive subcutaneous emphysema of the breast. This case highlights that the fibrous tissue capsule around a breast implant can function as an anatomical space in continuity with the thoracic cavity, masking the diagnosis of pneumothorax in penetrating trauma.