Bone Pathology Database

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2nd image
MRI with Gd enhancement
On plain X ray (previous page) calcification anterior to the ankle joint can be seen. The MRI image shows a mass anterior to, and extending into the anterior lip of the ankle joint. The ankle had already been biopsied at the time this MRI was taken. It suggests that he biopsy was incomplete and that some tumour tissue remained.
Most tumors display heterogeneous intermediate signal-intensity on T1-weighted images. Lesions smaller than 5 cm are more likely (40%) to have predominantly homogeneous signal intensity similar to that of adjacent muscle. Larger lesions are most often heterogeneous secondary to extensive areas of hemorrhage and necrosis.

On T2-weighted images, lesions are usually hyperintense, with signal intensity similar to or lower than that of fatty tissue. Considerable inhomogeneity is demonstrated in 82% of lesions, with cystic components seen in 77% . Cystic components with striking fluid-fluid levels are demonstrated in 18% of tumors. Approximately one third of lesions demonstrate the so-called triple signal pattern on T2-weighted images.

This pattern consists of the following:

  1. Mixtures of hyperintense fluid with or without fluid levels,
  2. Intermediate signal similar to muscle,
  3. Slightly hypointense signal similar to that of fibrous tissue.

Apposition to bone surfaces without a clear plane of separation is seen in 50-59% of cases as was seen in this case with clear bone erosion or destruction in 22% . Calcifications are not easily seen on MRIs, and they are usually hypointense on images obtained with all sequences. The straight x ray on the previous page shows these calcifications.

The straight x ray on the previous page shows these calcifications.
Approximately 30% of patients have calcifications that are detectable radiographically



Record 86