A surface lesion of bone may arise within the cortex, between the cortex and the periosteum, within the periosteum, or in the tissues immediately adjacent to the periosteum including tendinous and ligamentous attachments. While these lesions generally reflect the spectrum of more common intramedullary lesions and have an appearance similar to that of their intramedullary counterparts, their unusual surface origin often renders diagnosis difficult. Surface sarcomas are usually of a lower grade than that of the intramedullary tumor, and often they have a more favorable prognosis. Traumatic lesions of the bone surface are common and should be considered in the differential diagnosis of a surface lesion, especially in the young or athletic individual. An elevated peripheral white blood cell count and erythrocyte sedimentation rate may herald an infection of the bone surface.