19-year-old male with history of T-cell lymphoma and chronic osteomyelitis. MENISCI: No significant abnormality noted.ARTICULAR CARTILAGE AND BONE: There are numerous geographic lesions with serpentine and sclerotic borders within the distal femur, proximal tibia, and proximal fibula likely representing avascular necrosis appearing similar to prior.Within the proximal tibia in an area of superimposed AVN, there is a large irregular heterogeneous area of signal abnormality consisting of decreased T1 and increased T2 signal abnormality with avid enhancement after contrast administration. This lesion breaks through cortex laterally and extends into the soft tissues where there is extensive increased T2 signal abnormality (image 14 of series 1001). There is periosteal reaction about the proximal tibia. Marked edema type signal abnormality about the subcutaneous fat of the proximal lateral lower leg.LIGAMENTS: No significant abnormality noted. EXTENSOR MECHANISM: No significant abnormality noted.ADDITIONAL
1. Large heterogeneous lesion within the proximal tibia in the background of chronic AVN. There is new cortical breakthrough laterally as well as a small soft tissue component. While osteomyelitis is a diagnostic consideration, the lesion does not appear as fluid, but actually enhancing soft tissue. Given this, a malignant lesion must be entertained. Further evaluation with nuclear medicine could be useful or consider tissue sampling.2. Avascular necrosis of the distal femur and proximal tibia/fibula appearing similar to prior.