May Be Caused by

 Common

Acromioclavicular joint osteoarthritis

Bone sarcoma

Ewing sarcoma

Fracture with callus

Langerhans cell histiocytosis

Metastasis

Osteomyelitis

Osteosarcoma

Paget disease of bone

Septic arthritis of the acromioclavicular joint

Septic arthritis of the sternoclavicular joint

Sternoclavicular joint osteoarthritis

 Uncommon

Avascular necrosis

Caffey disease

Condensing osteitis of the clavicle

Endosteal hyperostosis van Buchem type

Endosteal hyperostosis Worth type

Hodgkin disease

Hypertrophic osteoarthropathy

Hypervitaminosis A

Leukemia

Lymphoma

Osteoid osteoma

Osteoma

Sternocostoclavicular hyperostosis

Tietze syndrome