A 6-year-old boy with long-standing right knee pain was initially investigated by x-ray depicting a lytic lesion involving the proximal tibia. A biopsy of the lesion was done and the results were shown below.

Histopathology report:

Biopsy of the right upper tibia bone lesion shows a lobulated tumor formed of hypo and hypercellular areas with myxochondroid islands alternating with cellular fibrous areas containing many osteoclastic giant cells. Scanty mitotic figures are seen. No tumor necrosis is seen. Features are consistent with chondromyxoid fibroma. Radiopathological correlation is recommended.

As the histopathology report recommended further evaluation of the bone lesion. MRI was done and show findings compatible with Chondromyxoid fibroma.