Bilateral erosion or absence of the lateral ends of the clavicles may be seen in hyperparathyroidism, rheumatoid arthritis, scleroderma and cleidocranial dysostosis. The smooth tapered appearance in this case favours rheumatoid arthritis or scleroderma. Other causes are post-traumatic osteolysis, myeloma, metastases and infection which are usually unilateral.

Reference: Dahnert W. Radiology Review Manual, 5th edition. Lippincott, Williams and Wilkins 2003
Credit: Dr Donna D’Souza