Intramuscular Dissection of a Large Ganglion Cyst Into the Gastrocnemius Muscle

Full article available online at Healio.com/Orthopedics. Search: 20120621-36 Ganglion cysts are lesions resulting from the myxoid degeneration of the connective tissue associated with joint capsules and tendon sheaths. Most common around the wrist joint, ganglion cysts may be found elsewhere in the body, including in and around the knee joint. Uncommonly, ganglion cysts can present intramuscularly. Previous reports document the existence of intramuscular ganglia, often without histologic confirmation. This article describes a case of an intramuscular ganglion cyst in the medial gastrocnemius muscle of a 53-year-old woman. The patient initially presented for discomfort associated with the lesion. Examination was consistent with intramuscular cystic lesion of unknown etiology. Ultrasound and magnetic resonance imaging revealed the origin of the mass at the semimembranosus–gastrocnemius bursa. Because of its location, the mass was initially suspected to be a dissecting Baker’s cyst, an uncommon but previously reported diagnosis. The patient underwent surgical excision, and examination of the intact specimen revealed a thin, fibrous, walled cyst with no lining epithelium, which was consistent with a ganglion cyst. To the authors’ knowledge, this is the first report in the orthopedic literature of a ganglion cyst dissecting into the gastrocnemius muscle. Because ganglion cysts commonly require excision for definitive treatment and do not respond well to treatment measures implemented for Baker’s cysts, including resection of underlying meniscal tears, the authors believe it is important for orthopedic surgeons to be able to distinguish between Baker’s and other cysts associated with the knee joint, including ganglion cysts, which may require more definitive treatment. Mr Nicholson and Dr Freedman are from the Department of Orthopaedics, Tufts University School of Medicine, Boston, Massachusetts. Mr Nicholson and Dr Freedman have no relevant financial relationships to disclose. Correspondence should be addressed to: Luke T. Nicholson, BS, Department of Orthopaedics, 800 Washington St, Tufts Medical Center #306, Boston, MA 02111 (luke.nicholson@tufts.edu). doi: 10.3928/01477447-20120621-36 Intramuscular Dissection of a Large Ganglion Cyst Into the Gastrocnemius Muscle Luke T. NichoLsoN, Bs; haroLd L. FreedmaN, md e1122 Figure 2: T2-weighted axial magnetic resonance image revealing an intramuscular cyst of the medial gastrocnemius muscle. 2 Figure 3: Photograph of gross specimen. 3 Figure 1: Short T1 inversion recovery sequence coronal magnetic resonance image revealing an intramuscular cyst of the medial gastrocnemius muscle. 1