Ganglion cyst
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A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath.<ref name=AAOS2013>Template:Cite web</ref> It most often occurs at the back of the wrist, followed by the front of the wrist.<ref name=AAOS2013/><ref name=Fer2014>Template:Cite book</ref>
The cause is unknown.<ref name=AAOS2013/> The underlying mechanism is believed to involve an outpouching of the synovial membrane.<ref name=Fer2014/> Diagnosis is typically based on examination. The ability to shine light through the bump or any past decrease in size supports the diagnosis of the bump as a ganglion cyst.<ref name=Fer2014/> Ganglion cysts are usually obvious upon observation. Medical imaging may be considered on infrequent occasions to rule out another diagnosis.<ref name=AAOS2013/><ref name=Fer2014/>
Treatment is not necessary. Options for treatment include needle aspiration or surgery.<ref name=AAOS2013/> About half the time, they resolve on their own.<ref name=Fer2014/> About three per 10,000 people develop a ganglion cyst of the wrist or hand a year.<ref name=Co2011>Template:Cite book</ref>
Presentation
The average size of these cysts is Template:Convert, but excised cysts of more than Template:Convert have been reported.<ref name="Camasta">Template:Cite web</ref> The size of the cyst may vary over time. Between 50 and 70% of all masses on the hand and wrist are ganglion cysts.<ref>Template:Cite book</ref><ref>Template:Cite book</ref><ref name=Mao12>Template:Cite journal</ref>
Wrist
They commonly are found near the wrist joint, especially at the scapholunate area.<ref name="BSSH">Template:Cite web</ref>
Common wrist ganglions include:
- dorsal wrist ganglion<ref name=Pal14>Template:Cite book</ref><ref>Template:Cite book</ref>
- volar wrist ganglion<ref name=Pal14 /><ref name=Cooper07>Template:Cite book</ref>
- extensor retinaculum ganglion<ref name=Pal14 />
- occult ganglion<ref name=Pal14 /><ref name=Cooper07 />
- intraosseous ganglion<ref name=Pal14 />
- mucous cyst<ref name=Pal14 /><ref name=Cooper07 />
Foot
In a 2007 study of patients in Glasgow whose foot lumps were removed surgically, 39 of 101 cases were ganglion cysts. The study replicated earlier findings that no ganglion cysts were found on the sole or heel. The authors wrote, "Although lumps in these areas may be ganglia, the surgeon should probably consider other diagnoses in the first instance." The researchers noted a preponderance of occurrence among females (85%) and that 11 of the other cases had been misdiagnosed as ganglion cysts before surgery.<ref>Template:Cite journal</ref>
Lower extremity
Ganglion cysts are not limited to the hands and feet. They may occur near the knee, mostly within and near the anterior cruciate ligament,<ref name=Mao12 /> but they may occur at the origins of the gastrocnemius tendon, and anteriorly on Hoffa's infrapatellar fat pad.<ref>Template:Cite book</ref> Most patients with a ganglion cyst of the knee present with both pain and a restricted range of motion, but these findings are variable, and some patients may have neither.<ref name=Mao12 />
Other
From their common origin at a joint or tendon, ganglion cysts may form in a wide range of locations. At the shoulder, they typically occur at the acromioclavicular joint or along the biceps tendon,<ref>Arend CF. Ultrasound of the Shoulder. Master Medical Books, 2013. Sample chapter available on acromioclavicular joint ganglion Template:Webarchive.</ref> and are occasionally known to cause nerve compression or bone erosion.<ref>Template:Cite book</ref> Rarely, intraosseous ganglion cysts occur, sometimes in combination with a cyst in the overlying soft tissue.<ref name=Camasta /><ref>Template:Cite journal (includes MRI images)</ref> It is possible for a cyst to be considerably displaced from the joint. In one extreme case, a ganglion cyst was observed to propagate extensively via the conduit of the common peroneal nerve sheath to a location in the thigh; in such cases surgery to the proximal joint to remove the articular connection may remove the need for a riskier, more extensive surgery in the neural tissue of the thigh.<ref>Template:Cite web</ref> The cysts may intrude into the spine, which may cause pain and dysesthesia in distant extremities.<ref name=Kim />
Cystic adventitial disease, in which a cyst occurs within the popliteal artery near the knee, has been proposed recently to occur by an articular mechanism, with a conduit leading from the joint, similar to the development of ganglion cysts, that spreads within the peroneal nerve.<ref>Template:Cite journal</ref> One uncommon location of the cysts are in the muscle tendons of the hand, such as the extensor digitorum superficialis.<ref>Template:Cite journal</ref>
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Cyst on right wrist -
Cyst on dorsum of right foot -
Cyst on a finger -
Small cyst on right index finger -
small cyst on thumb lanced with red-hot needle -
Ganglion cyst on the palmar side of the left wrist
Causes
The exact cause is unknown.<ref name=Mao12 /> The most commonly accepted probable cause of ganglion cysts is the herniation hypothesis, by which they are thought to occur as an out-pouching or distention of a weakened portion of a joint capsule or tendon sheath. This description is based on the observations that the cysts occur close to tendons and joints. The microscopic anatomy of the cyst resembles that of tenosynovial tissue. The fluid is similar in composition to synovial fluid. Dye injected into the joint frequently ends up in the cyst. Dye injected into the cyst rarely enters the joint, however, which has been attributed to the apparent formation of an effective and one-way "check valve", allowing fluid out of the joint, but not back in.<ref name=Camasta />
In synovials, post-traumatic degeneration of connective tissue and inflammation have been considered as causes. Other possible mechanisms for the development of ganglion cysts include repeated mechanical stress, facet arthrosis, myxoid degeneration of periarticular fibrous tissues and liquefaction with chronic damage, increased production of hyaluronic acid by fibroblasts, and a proliferation of mesenchymal cells.<ref name=Kim>Template:Cite journal (original source cites eight additional references for the quoted paragraph)</ref><ref>Template:Cite book</ref>
Diagnosis
Ganglion cysts are diagnosed easily, as they are visible and pliable to touch.
Ultrasonography (US) may be used to increase diagnostic confidence in clinically suspected lesions or to view smaller "occult" cysts as a cause of dorsal wrist pain with forceful extension.
Treatment
At least 33% resolve without treatment within six years, and 50% within 10 years.<ref name=Au2018>Template:Cite web</ref>
Surgical excision is the primary discretionary, elective treatment option for ganglion cysts. Alternatively, a hypodermic needle may be used to drain the fluid from the cyst (via aspiration).<ref name="gale">Template:Cite book</ref> The recurrence rate is about 50% following aspiration of a ganglion cyst.
Complications
Complications of treatment may include joint stiffness and scar formation.<ref name=gale /> Recurrence of the lesion is more common following excision of a volar ganglion cyst in the wrist. Incomplete excision that fails to include the stalk or pedicle also may lead to recurrence, as will failing to execute a layered closure of the incision.<ref>Camasta, Craig A., DPM, Excision of the Ganglion Cyst Template:Webarchive, podiatryinstitute.com, update 1993, 1993 33 pdf, pages 181–5</ref>
Prognosis
Recurrence rate is higher in aspirated cysts than in excised ones.<ref name=md>Template:Cite book</ref> Ganglion cysts have been found to recur following surgery in 12%<ref>Template:Cite journal</ref> to 41%<ref>Template:Cite journal</ref> of patients.
A six-year outcome study of the treatment of ganglion cysts on the dorsal wrist compared excision, aspiration, and no treatment. Neither excision nor aspiration provided long-term benefit better than no treatment. Of the untreated ganglion cysts, 58% resolved spontaneously; the postsurgery recurrence rate in this study was 39%.<ref name="pmid17950209">Template:Cite journal</ref> A similar study in 2003 of ganglion cysts occurring on the palmar surface of the wrist states: "At 2- and 5-year follow-up, regardless of treatment, no difference in symptoms was found, regardless of whether the palmar wrist ganglion was excised, aspirated, or left alone."<ref>Template:Cite journal</ref>
Etymology
Being a misnomer that has persisted into modern times,<ref>Template:Cite book</ref> the ganglion cyst is unrelated to the neural ganglion or ganglion cell; its etymology traces back to the ancient Greek Template:Lang, a 'knot' or 'swelling beneath the skin',<ref>Template:Cite web</ref> which extends to the neural masses by analogy. Generally, Hippocrates is credited with the description of these cysts.<ref name=Camasta /><ref>See Hippocrates' "On the Articulations" (part 40) at Wikisource</ref>
"Bible bump"
An historical method of treatment for a ganglion cyst was to strike the lump with a large, heavy book, causing the cyst to rupture and drain into the surrounding tissues. Historically, a Bible, usually the largest (or only) book in a household, was employed for this treatment. This practice led to the nickname of "Bible bumps" or "Gideon's disease" for the cysts.<ref name="E-hand.com" /><ref name="BMJ Case Reports">Template:Cite journal</ref> This treatment risks injuring the person and thus is not recommended.<ref>Template:Cite web</ref><ref name="eatonhand.com">Template:Cite web</ref>