Radiologic and pathologic findings were analyzed in four patients with parosteal osteosarcomas, three with periosteal osteosarcomas and one with a high-grade surface osteosarcoma. Plain film and histologic findings considered together are usually distinctive and permit differentiation of these tumors from each other and from other lesions with which they are frequently confused. Prognosis and management are determined by tumor extent and histologic grade. Computed tomography is more accurate than conventional tomography, angiography, and bone scintigraphy for preoperative determination of tumor extent and for assessing tumor relationships to the bone cortex and medullary cavity. Histologically, parosteal osteosarcomas are usually low-grade, while periosteal and high-grade surface osteosarcomas are generally high-grade tumors and have worse prognoses. High-grade surface osteosarcoma, which is indistinguishable in behavior and histology from classical medullary osteosarcoma, requires more aggressive surgical management than parosteal and periosteal osteosarcomas.

A 70-year-old man presented with increasing swelling of 2 years’ duration, on the dorsal aspect of the forefoot. Imaging studies revealed a heavily calcified surface lesion of bone with early invasion of the underlying second metatarsal. Both imaging findings and the subsequent resection histology were consistent with a parosteal osteosarcoma, which is particularly rare at this site and at this age. The differential diagnosis of a mineralizing surface lesion of bone arising in the foot is discussed.

This article presents a case of juxtacortical (paraosteal) osteosarcoma in a 43-year-old female, which is rare malignant mesenchymal tumor. As per the literature, it accounts for less than 4% of all osteosarcomas. Due to its rare variety, this tumor can cause diagnostic dilemma and clinicians should be aware of it. Due to its clinical picture, it can be confused with peripheral fibro-osseous lesions. Success rate of treatment are good if the tumor is detected early and resected with wide margins giving a negligible chance for recurrence.

The authors report a rare case of juxtacortical osteosarcoma of the radius in a child. The diagnosis and treatment were delayed because of misleading and wrongly reassuring radiological and histological aspects. The 12-year-old boy was admitted for a tumefaction of the proximal extremity of the right radius noticed after trauma. Physical examination showed a hard and slightly painful swelling. Xrays showed an irregular osseous mass developed from the superior metaphysis of the radius and encircling it. MRI showed a juxtacortical tumor with medullary involvement. A biopsy concluded to a fracture callus. Ten months later, the tumor became painful and homogeneous, regular and well defined on Xrays. A repeat biopsy showed juxtacortical osteosarcoma. Enbloc resection of the tumor was done. After a follow-up of 2 years, the child is alive without recurrence and metastasis and with a satisfactory function of the upper limb.