Fibroma of the peroneus longus tendon sheath in a child: a case report.

Tendon sheath fibromas are rare, benign soft-tissue tumours and usually involve tendons of the upper extremities, particularly the fingers. The most common presentation is a painless, slow-growing swelling. Tendon sheath fibromas are composed of dense fibrocollagenous stromas with scattered, spindle-shaped fibroblasts and narrow, slit-like vascular spaces. Ultrasonography and magnetic resonance imaging are useful diagnostic tools. We report on an 11-year-old boy with a fibroma involving the right peroneus longus tendon sheath.