Magnetic resonance imaging of hereditary hernias of the peroneus longus muscle.

Herniation of the left peroneus longus muscle was present in three male members of the same family, being the first reported case of this condition in a familial setting. The hernias were differentiated from other mass lesions and varices by magnetic resonance imaging. The images demonstrated a fascial defect originating in the area where vessels and nerves penetrate the fascia, suggesting that the three men had a congenital weakness in the fascia.