Telangiectatic osteosarcoma

An ovoid poorly defined expansile lytic lesion is seen involving the central medullary cavity of proximal shaft of ulna. There is wide zone of transition with no clear demarcation/sclerosis. No matrix calcification is seen. There is cortical breach with interrupted periosteal reaction posteriorly. Mild overlying soft tissue swelling is present. There is no pathological fracture.

A heterogeneous predominantly cystic mass involving proximal ulna. There is evidence of cortical breach posteriorly. Multiple internal small internal locules noted separated by thin echogenic internal septae. Cyst fluid shows bright internal echoes. Vascularity is seen at the periphery of the mass.

A large lytic soft tissue mass is seen involving the central medullary cavity of proximal shaft of the ulna. The soft tissue mass is eroding the posterior cortex and extending into the overlying soft tissues. The mass consists of multiple cystic spaces of varying signal intensities separated by thin hypointense septae. The cystic spaces are mostly hyperintense on T1 as well as T2-weighted images indicating internal hemorrhage. Extensive fluid-fluid levels are seen. Relatively narrow zone of transition is seen in the ulna with no marrow edema in the adjoining segments. Mild edema in the surrounding muscles is noted. On post contrast scans, moderate heterogeneous enhancement of the mass is seen, mainly at the periphery and in the septae. Prominent enhancement of the surrounding muscles is also noted.