A 23-year-old male patient consulted a doctor about pain occurring in the lower third of the thigh with weight bearing activities and unloaded. The patient denies any injuries to the region. Objectively: the skin is of normal color, deep palpation reveals pastosity and tenderness, movements of the knee joint are limited. Radiograph of the distal femoral metaepiphyseal region shows a zone of degradation and spicules. In blood: immature cells are present, there are no signs of inflammation. What is the most likely diagnosis?