Metachronous ganglion cysts: illustrative case

Area of Science:

• Orthopedics
• Neurology
• Surgical Pathology

Background:

• Ulnar neuropathy at Guyon's canal is rare but often linked to ganglion cysts.
• The exact cause of these cysts, particularly at unusual locations, is debated.
• The articular theory suggests joint connections facilitate cyst formation.

Purpose of the Study:

• To reevaluate a case of recurrent ulnar intraneural ganglion cysts challenging the articular theory.
• To investigate the pathogenesis of extraneural, intraneural, and adventitial cysts at Guyon's canal.

Main Methods:

• Reinterpretation of serial MR images from a patient with recurrent ulnar intraneural cysts.
• Surgical and imaging data review to identify potential articular connections.
• Analysis of cyst development post-treatment in relation to the wrist joint.

Main Results:

• No discrete articular branch was initially identified.
• New cysts (adventitial, soft tissue ganglion) developed sequentially from the same wrist joint.
• An unrecognized small wrist connection to the ulnar intraneural ganglion was found.

Conclusions:

• The case supports the articular theory for various cyst types (intraneural ganglion, adventitial, soft tissue).
• Scarring altered nerve pathways, leading to new cyst formation through adjacent joint capsular rents.
• Untreated joint connections are critical in the recurrence and propagation of these cysts.