Chest wall tumours of bones in childhood are rare in general. Chest wall aneurysmal bone cysts (ABC) are even rarer. If happened, they affect spine and long bone, those affect chest wall are extremely sparse. We are presenting a case of 8-year-old girl who presented with spontaneous hemothorax. We share our experience and diagnostic dilemma we encounter in emergency situation as well as challenging in the management. Aneurysmal bone cysts, despite being benign, but, rarity and unusual presentation added to atypical radiological features may lead to catastrophic consequences unless diagnosed on time.