logo logo
Search: Organ site Search: Tumor / Syndrome
or
WHO Classification of Tumours
Parosteal osteosarcoma
Bone


Definition

Parosteal osteosarcoma is a low grade osteosarcoma arising from the surface of bone. Approximately 70% of cases affect the distal posterior femur; other common sites are the proximal tibia and the proximal humerus. The tumour presents as a heavily mineralized, lobulated mass attached to the underlying cortex and shows a tendency to wrap around the involved bone. Histologically, parosteal osteosarcoma consists of parallel bony trabeculae in a hypocellular stroma. About 50% of the tumours show cartilaginous differentiation
Click for details
Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
3rd Edition
IARC Press: Lyon 2002



.
Parosteal osteosarcoma predominantly affects young adults, with a slight predilection for females. The prognosis after complete excision is usually excellent; marrow invasion and moderate cytological atypia do not predict a worse outcome. If incompletly excised, the tumour may reccur and dedifferentiate; such dedifferentiation is associated with a prognosis similar to that of conventional osteosarcoma

Click for details
Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
3rd Edition
IARC Press: Lyon 2002



.