An 8-year-old child presented with pain at shoulder and arm. A X-ray reveals a uniform well-defined lucent lesion at the metaphysis. Most likely diagnosis is?(AIIMS 2016)

Ans. A Simple bone cystLucent geographic lesion seen in humeral metaphysis in a child is most commonly a simple bone cyst. Trapdoor signQ/Fallen fragment signQ/Hinged fragment signQ may be seen.