Figure 24. Guyon tunnel syndrome. Photograph (bottom right) shows the area scanned. Transverse (left) and sagittal (top right) US scans show a well-defined hypoechoic nodule (arrowheads) in the wrist, compressing the ulnar nerve (arrows) in a 48-year-old man in whom leiomyoma was diagnosed. Color Doppler image (bottom left) shows the ulnar nerve (A) located between the tumor and ulnar artery.