Anomalous Extensor Indicis Proprius Muscle

79 Anatomic variations in the musculotendinous structure of the hand and wrist are particularly important in repairing or reconstruction of hand injuries. We report here an extensor indicis proprius (EIP) tendon with an unusual appearance, which is associated with dorsal wrist pain. A 30-year-old man who worked as a cook presented with a painful mass-like lesion on the dorsum of the right hand (Fig. 1). The pain had been aggravated recently by forceful movement of the wrist over the previous 2 months, especially during cooking. At first, it was thought to be a ganglion. However, because the aspiration test was negative, it was clinically considered to be tenosynovitis. Because conservative management failed to relieve his symptoms, a sonographic examination was performed (Fig. 2). Anomalous muscle was identified, and the patient underwent surgical treatment. Anomalous Extensor Indicis Proprius Muscle