Figure 16c. Synovial hemangioma of the knee. (a) Axial T1-weighted MR image shows an intermediate-signal-intensity lesion in the suprapatellar pouch (arrow) containing areas of high signal intensity. (b) On a corresponding axial fat-suppressed T2-weighted MR image, the lesion demonstrates the characteristic circular-linear pattern (arrow). (c) Photomicrograph (original magnification, x200; H-E stain) depicts the synovial membrane with vascular proliferation (arrows) and vacuoles in the subjacent tissue (arrowheads).