Abstract
Polymelia is an extremely rare congenital anomaly where an individual is born with an abnormally developed extra or supernumerary limb which is generally shrunken and functionless. A case of thoracomelia (a type of polymelia) was observed macroscopically and confirmed radiologically in 1.5 years old boy born in Nepal with an abnormal supernumerary upper limb attached to his back in the thoracic region. The limb was successfully amputated, and the boy had a favorable outcome after surgical treatment, without any adverse effects or impairment. Understanding the embryogenesis of thoracomelia is essential for unraveling the complex mechanisms underlying this condition and potentially aiding in early diagnosis and intervention. This case report and review aims to shed light on the intricate processes governing forelimb formation and their perturbations leading to thoracomelia.