CT confirms the plain film appearance of the previous image, revealing a sharply demarcated epiphyseal lucent lesion but with faintly sclerotic margins. It transgresses the growth plate into the anterior part of the metaphysis. There is no periosteal reaction, however there does appear to be a cortical breach anterosuperiorly into the knee joint. No matrix calcification or extra-osseous soft tissue component can be demonstrated. Case produced with permission, courtesy of Dr. Frank Gaillard. Radiopaedia. Complete case is here.