The first described joint-associated intraneural ganglion cyst.

This article describes the identification of the first known specimen in which an articular origin for an intraneural cyst was recognized. Prompted by early citations in the 20th century of a valuable 1904 tibial intraneural ganglion housed at St. Bartholomew's Hospital in London, we traveled there to research it. We fortuitously discovered a citation to an earlier joint-related specimen, one that had not previously been referenced correctly in subsequent publications on intraneural cysts for more than a century. The original anatomic description dating to 1884, summarized in 3 lines in a museum catalog, was attributed to T. Swinford Edwards. This cadaveric specimen affected the deep branch of the ulnar nerve and arose from a carpal joint. Additional information was provided in a Transactions in 1884. An original drawing of the specimen was published in a textbook written in 1889 by Anthony Bowlby, a former curator, both of which credited F. (Frederick) Swinford Edwards, a demonstrator in anatomy and surgery at St. Bartholomew's. Unfortunately, the specimen could not be located and is presumed lost. To establish this specimen as the first known example of a joint-related intraneural cyst, we completed a review of >400 other cases and confirmed this statement. The first observation of an articular origin for an intraneural cyst, made by 2 eminent surgeons, has not been properly acknowledged. Considered with a modern perspective, this historical case solidifies the articular (synovial) origin for these unusual intraneural cysts, a finding that has important treatment implications.

Intraneural ganglion cyst: a 200-year-old mystery solved.

We describe the first reported case of an intraneural ganglion cyst, an ulnar ("cubital") intraneural cyst, which, on literature review, dated to 1810. For over 80 years, its original brief description by Beauchêne was wrongly attributed to Duchenne, effectively making the reference and specimen inaccessible to scrutiny. Fortunately, the intact cyst had been safely housed in the Musée Dupuytren, Paris, France, thus permitting its examination. Although originally described as a "serous" cyst, our present understanding of the anatomy of the ulnar nerve and of peripheral nerve pathology allowed us to reinterpret it as a mucin-filled, elbow-level, ulnar intraneural ganglion cyst. In addition to its description as a fusiform cystic enlargement of the nerve, we documented similar enlargement of a lumen-bearing branch, the articular branch at the level of the elbow. Based on our assessment of the specimen and with a modern perspective, we concluded that the origin of the cyst was from the postero-medial aspect of the elbow joint and that its fluid content, having dissected through a capsular defect, followed the path of the articular branch into the parent ulnar nerve. The purpose of this report is to clarify historical misconceptions regarding the pathogenesis of this controversial entity.