Fibular osteosarcoma-Imaging

29 year old adult with pain in his leg. case submitted by Dr MGK Murthy, Mr Hari Om and Mr Sahadev.

Plain Film: There is large  ill defined , diffuse , grossly destructive , predominantly  bone forming  lesion seen involving the metadiaphyseal regions of fibula with wide zone of transition, large soft tissue swelling.  Possibility of primary bone tumor of malignant etiology at this stage.

Next most cost effective  investigation: Today MRI (preferably  with contrast)  combined with Fluorine (F18) bone scan is considered as the Platinum standard in Clinical Practice , as it would give us bone(CT in it), Chest (F18bone scan being whole body)(for excluding secondaries/infective focus), MR for Soft tissue evaluation, contrast for showing  soft tissue invasion of the tumor tissue

MRI findings:  It shows large, ill defined, mildly expansile and grossly destructive metadiaphyseal  lesion of fibula upperend with complete loss of Soft tissue  differentiation(suggesting involvement), with areas of new bone formation , and loss of periosteal definition.

MR is supposed to show non-mineralized tissue as intermediate on T1 and bright on T2, new bone formation as persistently low on all sequences, loss of tissue interfaces including intermuscular fat planes and presence of blood as varying heterogenous signals , along with sunburst appearance/codman’s triangle for periosteal contact etc. Other relevant features expected to helpfor surgery are vessel encasement and extension across the knee  joint  surface, and tibiofibular syndesmosis

Follow up: Chest X ray in this case was negative and bone Biopsy revealed Primary-bone forming malignant neoplasm – osteosarcoma  of possibly intramedullary variety .