<prompt> A 10 year old boy was found to have a symmetric radiolytic lesion on the X-ray at the upper end of the right humerus after being admitted for fracture of humerus. Such a lesion is present on the left humerus as well. What is the likely pathology?Unicameral bone cystOsteosarcomaOsteoclastomaAneurysmal bone cyst  <response>: The age of the child, symmetric radiolytic lesion on the upper end of the humerus on both sides with the history of fracture are suggestive of a case of unicameral bone cyst. Ref: Textbook of Disorders and Injuries of the Musculoskeletal System By Robe Bruce Salter, Pages 398-399 ; Essentials in Bone and Soft-Tissue Pathology By Edward F. McCahy, Jasvir S. Khurana, Paul J. Zhang, 2010, Page 70 ; Musculoskeletal Imaging: A Concise Multimodality Approach By Klaus Bohndorf, Herwig Imhof, Thomas Lee Pope, 2001, Page 162 