Male/23 years old was presented with knee swelling on the left side.

MRI left knee showed approximately  44x50x90mm accumulated bony lesion involving upper tibial shaft extending and primal metaphysical, medial tibial condyle, intercondylar portion of tibia, lateral tibial condyle and it is causing scalloping/ pressure erosion of medial cortex of tissue, altered signal in the soft tissue around the upper tibia in medial, lateral, posterior aspect represent edema with altered signal in mid, distal portion of anterior cruciate ligament which is mildly edematous followed biopsy from left knee joint done and HPE showed round cell malignant tumor with extensive necrosis and biopsy  IHC showed primitive neuroectodermal tumor/Ewing sarcoma and PET CT  scan done showed Intense FDG avidity seen corresponding to mixed lytic sclerotic changes involving the diaphysis and metaphysis of left proximal tibia with extension into the proximal medullary cavity with multiple tiny breaches seen in the overlying periostenum and intense FDG avidity seen in the soft tissue graft seen superficial to bony lesion(SUV max- including of the bone component of the lesion 54.9g/ml; tibial component of the lesion measures 5.3×4.5×9.7cm) with few non FDG avid minimally asymmetrical full appearing lymph nodes seen in the left inquinal and external iliac region(largest measures 1.8×0.6cm) and advised for VAC alternate I+E protocol and received total 4 cycles of chemotherapy followed MRI left knee joint with proximal leg done showed a fairly large geographical altered signal area in the proximal metaphysis of left tibia and multiple hypointense foci within the lesion on T1, T2 images with small magnetic sensibility artefact around it, likely represent calcification/hemosiderin in staining due to the blood products and lesion cause erosion of anteromedial and posterior cortex of proximal tibia and lesion reveals mild extension into the adjacent medial condyle and intercondylar region of tibia and upper margin of the lesion is around 9.8mm away from the lateral condyle of tibia is detected(lesion measures 8.0×3.4×4.4cm) and X-Ray left Knee A/P and Lateral periative lytic lesion with ill defined margin noted in proximal metaphyseal region of left tibia with minimal erosion of adjacent cortex noted and superiorly lesion appears to extend into medial condyle and intercondyler region without intra-articular extension and X-ray left leg showed Large primitive lytic lesion with ill-defined margin noted in proximal metaphyseal region of the tibia with minimal erosion of adjacent cortex noted and superiorly lesion appears to extend into medial condyle and intercondyle region without intra-articular extension followed Wide resection + Megaprosthetic TKR and HPE showed no residual viable tumor(ypT0) with given chemotherapy. So it can be possible to get the maximum possible response with proper chemotherapy with the qualified medical oncologists.