Plasmacytoma is a solitary or multiple tumor involving abnormal proliferation of plasma cells in soft tissue or bone tissue. It is divided into intramedullary or extramedullary plasmacytoma according to the site of invasion. Intramedullary plasmacytoma occurs in bone tissue, including Bone solitary plasmacytoma and multiple myeloma, extramedullary plasmacytoma most occur in the upper air gastrointestinal tract, including soft tissues such as the pharynx, tonsils, and paranasal sinuses [1, 2]. Giant cell tumor of bone is a bone tumor characterized by osteolytic multinucleated osteoclast-like giant cells filled between tumor stromal cells. A case of plasmacytoma of the clavicle admitted to the Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine (our hospital) was initially misdiagnosed as giant cell tumor of the clavicle. The medical history and diagnosis and treatment process are reported as follows.