On MRI, the soft tissue lesion encases the anterior aspect of the distal femoral metaphysis and associated with cortical thinning and erosion. It demonstrates isointense signal on T1 and heterogeneous signal on T2 with central component of intermediately low T2 signal intensity likely related to the dense osteoid matrix. Peripheral avid enhancement is noted. Perilesional oedema and mild diffuse intramedullary bone marrow oedema are seen. The constellation of findings are most likely representing periosteal osteosarcoma.