Primary Epiphyseal Aneurysmal Bone Cyst Of Distal Ulna

Aneurysmal Bone Cyst (ABC) is a benign expansile cystic blood filled reactive lesion of the bone, most common in the first 2 decades of life. Though it can involve any bone in the body but tibia, humerus, femur and posterior elements of spine are most commonly affected. They most commonly involve metaphysis or metaphysio-diaphyseal part of the bone. Primary involvement of epiphysis is rarely reported. Here we present a case of 6 year old male child with an epiphyseal ABC of distal ulna. Its diagnosis, surgical management, clinical outcome with review of literature is discussed.