Forearm soft tissue mass caused by an accessory muscle

Abstract

We present a case of forearm soft tissue mass caused by an accessory muscle, distal and deep to flexor carpi ulnaris muscle. Imaging studies, mainly magnetic resonance and ultrasound, allow a specific diagnosis, and obviate unnecessary surgery. In this case, the symptoms associated with ulnar compression led to surgery and confirmed the preoperative diagnosis.

Accessory flexor carpi ulnaris: case report and review of the literature

“…With regards to the imaging literature, there are several MRI illustrations of the accessory FCU in papers by Lemon et al 10 and Milena at al. 5 Milena et al 5 demonstrated a similar accessory muscle on ultrasound and MRI which also had an insertion to pisiform, as in our case. However, the accessory muscle in their case originated more proximally at the lateral edge of the elbow, blending with the ulnar attachment of pronator quadratus.…”

“…Given the position and location of the accessory muscle, there is potential for ulnar nerve entrapment syndrome with several reports of accessory FCU causing ulnar nerve symptoms that responded well to neurolysis and re-attachment of the distal tendon. 5,8 In the current case, there were no clinical symptoms of ulnar nerve entrapment. When considering ulnar nerve entrapment syndromes of the upper limb, it should be noted that the accessory anconeus epitrochlearis muscle can cause more proximal ulnar nerve compression in the cubital tunnel, having its origin at the medial epicondyle with insertion to the olecranon.…”

“…There are approximately 14 reported cases of Type III FCU anomaly in the anatomy and surgical literature. [2][3][4][5][6][7][8][9][10][11][12][13][14] The embryological basis of the anomaly is thought to be due to the anomalous separation of the flexor blastemal based on the morphology of the reported cases. 4 Based on the previous case reports and proposed embryological hypothesis, there are other potential anomalies associated with the Type III accessory FCU that include an absent PL, duplication of PL and flexor carpi radialis brevis, in addition to variations of the PL such as insertion onto the flexor retinaculum or median nerve innervation.…”

“…To the best of the authors' knowledge, this is only the second combined ultrasound and MRI description of an accessory flexor carpi ulnaris (FCU) muscle, and the first since 2001. 5…”

Ulnar and Humeral Heads Forming Separate Bellies: A Rare Case of Digastric Flexor Carpi Ulnaris Muscle

“…The ulnar slip of the tendon was inserted into the pisiform bone and the radial slip into the proximal phalanx of the ring finger. Lopez Milena et al (2001) have observed an anomalous DISCUSSION Not many variations of FCU are reported in the literature. Grechenig et al (2000) have conducted an Fig.…”