n Case Report

Intramuscular Dissection of a Large Ganglion Into the Gastrocnemius Muscle

Luke T. Nicholson, BS; Harold L. Freedman, MD

abstract Full article available online at Healio.com/Orthopedics. Search: 20120621-36

Ganglion are lesions resulting from the myxoid degeneration of the connec- tive tissue associated with capsules and tendon sheaths. Most common around the joint, ganglion cysts may be found elsewhere in the body, including in and around the joint. Uncommonly, ganglion cysts can present intramuscularly. Previous reports document the existence of intramuscular ganglia, often without his- tologic confirmation. 1 Figure 1: Short T1 inversion recovery sequence This article describes a case of an intramuscular in the medial gastrocne- coronal magnetic resonance image revealing an mius muscle of a 53-year-old woman. The patient initially presented for discomfort as- intramuscular cyst of the medial gastrocnemius sociated with the lesion. Examination was consistent with intramuscular cystic lesion muscle. 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 previ- ously 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 gan- glion cyst dissecting into the gastrocnemius muscle. Because ganglion cysts common- 2 ly require excision for definitive treatment and do not respond well to treatment mea- Figure 2: T2-weighted axial magnetic resonance sures implemented for Baker’s cysts, including resection of underlying meniscal tears, image revealing an intramuscular cyst of the me- the authors believe it is important for orthopedic surgeons to be able to distinguish dial gastrocnemius muscle. 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 3 Washington St, Tufts Medical Center #306, Boston, MA 02111 ([email protected]). doi: 10.3928/01477447-20120621-36 Figure 3: Photograph of gross specimen.

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he of juxta- neurovasculature distally and full knee articular cysts of the knee joint joint range of motion. No joint-line ten- Tincludes Baker’s cysts, meniscal derness existed, and no joint effusion was cysts, and ganglion cysts. Baker’s cysts appreciated. are common in with internal de- Because of the size, location, and rangement. They typically remain in the symptoms of the lesion, the patient un- popliteal fossa but have been reported to derwent surgical excision. The cyst was dissect intramuscularly.1,2 Meniscal cysts adherent to the gastrocnemius and are small cystic lesions associated with was dissected proximally in the muscle to meniscal tears that may present clinically a narrow neck, which was suture ligated as palpable masses in the joint line but have (Figure 3). Pathology revealed a thin, fi- not been reported to dissect intramuscular- brous, walled cyst with no lining epithe- ly. Ganglion cysts are commonly found in lium consistent with a ganglion cyst. 1 the wrist but occur elsewhere in the body, Figure 1: Short T1 inversion recovery sequence coronal magnetic resonance image revealing an including the knee joint, where they have Discussion intramuscular cyst of the medial gastrocnemius been described in intra- and extra-articular Ganglion cysts are thought to arise muscle. locations.3-6 To the authors’ knowledge, no from the myxoid degeneration of con- cases of intramuscular ganglion cysts of the nective tissue associated with a joint gastrocnemius muscle have been reported capsule or tendon sheath and, therefore, in the orthopedic literature. This article de- lack a true cell lining.7 The current article scribes a case of a patient who presented describes a histologically proven gan- with a large cystic medial calf mass that glion cyst arising at the gastrocnemius– was an intramuscular ganglion cyst. semimembranosus junction and dissect- ing into the belly of the medial gastroc- Case Report nemius muscle. The only other report of A 53-year-old woman presented with ganglia originating near this location is a 6-month history of a right proximal a series of 10 magnetic resonance imag- 2 medial calf mass that she reported to be ing-suspected ganglia appearing at the Figure 2: T2-weighted axial magnetic resonance increasing in size. The mass was painless head of the gastrocnemius, none of which image revealing an intramuscular cyst of the me- at rest but caused the patient significant were mentioned to dissect intramuscu- dial gastrocnemius muscle. discomfort with activities of daily living larly.4 The ganglia measured an average and prolonged standing. She reported no of 24 mm, and none were histologically history of trauma but had a history of ar- proven to be ganglion cysts.4 The current throscopic right anterior article is unique because of the intramus- (ACL) cyst removal 11 years previously; cular dissection of the large ganglion and no meniscal pathology was found at the its origination at the semimembranosus– time. gastrocnemius junction. On magnetic res- The patient initially presented to her onance imaging, this made the distinction 3 primary care physician 1 month previ- between Baker’s cyst and ganglion cyst Figure 3: Photograph of gross specimen. ously, where an ultrasound demonstrated difficult because Baker’s cysts are known an 833-cm septated cyst in the medial to originate at the semimembranosus– refer to Baker’s cysts and ganglion cysts gastrocnemius. A 1.5-T magnetic reso- gastrocnemius bursa. Previous literature interchangeably. However, they are patho- nance image with contrast revealed an has suggested that the origination of a cys- logically distinct entities with different 8.732.231.8-cm septated cystic mass tic lesion at this location excludes gangli- treatment options. It has been reported originating from the popliteal bursa and on cysts from the differential diagnosis.8 that 82% of synovial cysts are associated dissecting into the medial gastrocnemius The current report contradicts this notion. with a meniscal tear, the most common muscle with no edema or muscle enhance- This finding is important because the involving the posterior horn of the me- ment (Figures 1, 2). Physical examination potential exists to mistake a ganglion cyst dial meniscus9; thus, treatment is often revealed a firm, nontender cystic mass in of the knee joint for the more common aimed at treating the underlying menis- the right proximal medial calf with intact Baker’s cyst. Orthopedists commonly cal damage. If they are large enough to

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be symptomatic, Baker’s cysts may be as- References joint: a report of 85 cases and review of the literature. Knee Surg Sports Traumatol pirated; however, they are rarely excised. 1. Fang CS, McCarthy CL, McNally EG. Arthrosc. 2004; 12(2):123-129. Ganglion cysts have no underlying treat- Intramuscular dissection of Baker’s cysts: report on three cases. Skeletal Radiol. 2004; 7. Kumar V, Abbas A, Fausto N, Aster J. Bones, able pathology and have a high recurrence 33(6):367-371. , and soft-tissue tumors. In: Kumar V, rate when aspirated. Therefore, surgical Abbas A, Fausto N, Aster J, eds. Robbins 2. Chan YS, Wang CJ, Shin CH. Two-stage op- and Cotran Pathologic Basis of Disease. 8th excision is the gold standard for manage- eration for treatment of a large dissecting pop- ed. Philadelphia, PA: Saunders, Elsevier; ment should a patient’s symptoms warrant liteal cyst after failed total knee arthroplasty. J 2010:1247. Arthroplasty. 2000; 15(8):1068-1072. intervention.10,11 8. Torreggiani WC, Al-Ismail K, Munk PL, et 3. Jackson L, Namey TC. Ganglion cyst within al. The imaging spectrum of Baker’s (pop- the quadriceps muscle: evaluation with com- liteal) cysts. Clin Radiol. 2002; 57(8):681- Conclusion puted tomography and ultrasound. A case re- 691. port. Orthopedics. 1987; 10(8):1179-1180. This article describes the previously 9. Fielding JR, Franklin PD, Kustan J. Popliteal unreported intramuscular dissection of a 4. James SL, Connell DA, Bell J, Saifuddin A. cysts: a reassessment using magnetic reso- Ganglion cysts at the gastrocnemius origin: popliteal ganglion cyst into the gastrocne- nance imaging. Skeletal Radiol. 1991; a series of ten cases. Skeletal Radiol. 2007; 20:433-435. mius muscle. Given the possibility of mis- 36(2):139-143. 10. Gude W, Morelli V. Ganglion cysts of the diagnosis in similar cases, it is important 5. Kim JY, Jung SA, Sung MS, Park YH, Kang wrist: pathophysiology, clinical picture, and for orthopedists to understand the distinc- YK. Extra-articular ganglion cyst management. Curr Rev Musculoskelet Med. around the knee: focus on the associated 2008; 1(3-4):205-211. tion between cystic lesions of the poplite- findings. Eur Radiol. 2004; 14(1):106-111. al fossa because of their different treat- 11. Thornburg LE. Ganglions of the hand 6. Krudwig WK, Schulte KK, Heinemann C. and wrist. J Am Acad Orthop Surg. 1999; ment options. Intra-articular ganglion cysts of the knee 7(4):231-238.

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