Case ReportIntraneural ganglion cyst of the ulnar nerve in an unusual location: A case report

- Intraneural ganglion cysts are benign, mucinous, non-neoplastic lesions of the peripheral nerves that arise from the epineurium.
- An intraneural ganglion cyst involving the superficial branch of the ulnar nerve is a unique presentation.
- Regarding etiopathogenesis of the intraneural ganglion cysts, the latest and most affirmed theory is the unifying articular (synovial) theory.
- It is important to realize a related articular branch, otherwise the origin of cyst formation remains, and this may cause other para-articular cysts.
- Use of new 3-dimensional fast-spin echo-extended echo train MRI sequences may provide better visualization of the intraneural ganglions.

IntroductionIntraneural ganglion cysts are benign, mucinous, non-neoplastic lesions of the peripheral nerves. While the most common location of intraneural ganglion cysts is the ulnar nerve and its branches, intraneural ganglion cyst involving the superficial branch of the ulnar nerve has not yet been reported.Presentation of caseA-25-year-old woman presented with pain and a palpable mass in the hypothenar region of the volar side of her right hand. Her neuromuscular examination was normal. The pain was unresponsive to nonsurgical treatments. After confirming with imaging modalities, the initial diagnosis was considered as an intraneural ganglion cyst arising from superficial ulnar nerve. Excision of the ganglion and exploration of the articular branch (if seen in operation) decision was undertaken by the senior author. Whether MRI or intraoperative exploration, not identified an articular branch.DiscussionIntraneural ganglion cysts of peripheral nerves may be seen in miscellaneous locations in the body. However, to our knowledge, an intraneural ganglion cyst involving the superficial branch of the ulnar nerve is unique. While a variety of theories have been proposed to enlighten the etiopathogenesis of intraneural ganglia, the latest and most affirmed is the unifying articular (synovial) theory.ConclusionIntraneural ganglion cysts may be seen on the hypothenar side of the palm. The etiology and treatment of choice are closely associated with each other in this rare disorder. It is important to realize a related articular branch, otherwise the origin of cyst formation remains, and this may cause other para-articular cysts.