It is essential to exclude periosteal osteosarcoma from central osteosarcoma with periosteal extension, high-grade surface osteosarcoma and parosteal
More recently, a parosteal
osteoliposarcoma was reported , also defined by WDL and LGO coexistence, but arising from the cortex of the underlying bone just like parosteal
osteosarcoma, which in our case could not be proven by radiology, gross examination, or histology.
Surface osteosarcomas occur on the cortical surface within or deep to the periosteum and may largely protrude from (parosteal
) or extend circumferentially along the surface (periosteal) of the host bone; high-grade surface osteosarcoma may invade the medullary canal.
In the refracture due to periosteal, endosteal and parosteal
calluses the subcutaneous hematoma absent because periosteum closely attaches to the callus.
the ossification is found near or against bone 2.
Other new information relates to chondroblastoma, osteoblastoma, and parosteal
osteosarcoma, and the section on neoplasm simulators has been expanded to include conditions like neuropathic joint that may present as a neoplasm.
A contrast-enhanced magnetic resonace image (MRI) established the typical findings of parosteal
lipomas (PL) (Figure 3).
Similarly in series of periosteal and high-grade surface osteosarcomas [9-11] and parosteal
osteosarcomas [12,13], there was no reported association with radiation treatment.
Surface osteosarcomas include parosteal
("juxtacortical"), periosteal and high-grade surface subtypes.
 and Campanacci and Giunti  where the authors made the case for this being recognized as a distinct entity on the grounds of the unique radiographic and histologic features with a clinical behavior distinct from other surface-based osteosarcomas such as parosteal
osteosarcoma  and high-grade surface osteosarcoma .
It is noteworthy that conventional osteosarcoma (~10%), parosteal
osteosarcoma (>85%), and undifferentiated high-grade pleomorphic sarcoma of bone (~17%) may be positive for mouse double minute 2 homolog (MDM2) by fluorescence in situ hybridization
The common differential diagnosis of melorheostosis includes myositis ossificans, synovial osteochondromatosis, osteoma, parosteal
osteosarcoma, focal scleroderma, and Caffey disease.