Left tibia lesion. Evaluate characteristics. There is an elongated lesion within the proximal tibial diaphysis measuring approximately 11 cm in longitudinal dimension and occupying the width of the medullary space of the bone. The lesion is of heterogeneous signal intensity on T1-weighted images, predominantly iso- or slightly hypointense to skeletal muscle, but containing small foci of signal void, likely reflecting calcification, as well as higher signal intensity foci which may reflect small islands of spared fat. On fat-suppressed T2-weighted images the lesion is predominantly hyperintense, with components of relatively low signal intensity that may reflect calcification as seen on radiographs. Following intravenous contrast administration, there is thin rim enhancement peripherally, as well as nodular and ringlike enhancement centrally. The proximal and distal margins of the lesion are slightly nodular. There may be slight thinning of the cortex from expansile remodeling, but I see no focal cortical invasion or cortical signal abnormality. The remaining marrow signal intensity of the tibia is unremarkable, and the fibula appears normal. The musculature of the leg is normal. Please refer to the knee MRI report from the same date dictated under a separate accession number for details involving the menisci and articular cartilage. Degenerative arthritic changes affect the right knee as seen on the large field of view coronal images.
Proximal tibial lesion as described above most compatible with a cartilaginous neoplasm, most likely a benign enchondroma; while I cannot exclude the possibility of a low-grade chondrosarcoma the basis of this single imaging study, I see no aggressive features to suggest malignancy. Follow-up with radiography and consultation with orthopedic oncology may be considered.