What is ganglion cyst? Definition and Etymology
In Greek, ganglion means a ball-shaped swelling or knot under the skin . A cyst is a closed fluid-filled sac that is formed in the tissues . A ganglion cyst is a noncancerous fluid-filled sac that arises from the muscle tendon, tendon sheath, joint capsule or ligament, most commonly on the wrist or foot .
NOTE: Ganglion cysts have nothing to do with neural ganglions, which are clusters of neural cells inside the body.
Ganglion cysts grow due to an accumulation of fluid in them and not because of uncontrolled cell growth, like in benign tumors (lipoma, for example) . Ganglion cysts also do not spread and invade surrounding tissues, like cancers do. In most cases, a ganglion cyst is not dangerous but may cause stiffness or pain in the affected joint .
Picture 1. Ganglion cyst on the top of the right wrist
(source: DermNet NZ, CC license)
Ganglion cyst may also be called:
- Bible cyst or bump, because they were used to be treated by slamming with a heavy book, such as Bible  or Gideon Bible (and hence Gideon’s disease).
- Ganglionic cyst
- Mucous cyst, when it appears on the end knuckle of the finger
- Baker’s cyst or popliteal cyst, when it appears on the back of the knee
- Synovial cyst arises from the joint synovial sheath and is a true cyst (covered by epithelium on the inner side), so it is not the same as a ganglion cyst, but the appearance and treatment for both are similar [29,30,45].
- Bursal cyst arises from the bursa (a fluid-filled sac between the tendon and the joint) [11,30,38].
A ganglion cyst can develop in any joint, muscle or bone, but most common locations are shown in Picture 2 below:
Picture 2. Typical ganglion cyst locations
Wrist ganglion cysts most commonly appear on the back (top, dorsal) side, but also on the palmar (volar) side of the wrist . Wrist ganglions can arise from the muscle tendons or, rarely, from the wrist bones .
Picture 3. A ganglion cyst on the palmar (volar) side of the wrist
Picture 4. Ganglion cyst on the back (dorsal) side of the left wrist
(source: Wikipedia, CC license)
Common locations include the top of the foot  or, rarely, on the bottom of the foot (sole)  and the back of the heel in the Achilles tendon .
Picture 5. A ganglion cyst in the foot
(source: Webmedcentral, CC license)
Picture 6. A ganglion cyst in the foot
(source: Wikipedia, CC license)
Ganglion cysts can appear on the fingers or thumbs, either on the base of the finger (palm side) or on the end knuckle (back side), in which case it is called mucous cyst [3,5].
A ganglion cyst that appears at the back of the knee is called Baker’s or popliteal cyst [10,11].
Picture 7. An MRI image of a ganglion cyst behind the knee (Baker’s cyst)
(source: SciELO, CC license)
Other locations of ganglion cysts in the knee:
- Front of the knee (in the patellar tendon) [9,11] or in the anterior crucial ligament (ACL) 
- In the tendon of the quadriceps femoris muscle above the knee 
Picture 8. A ganglion cyst within the bone in the ankle
(source: faoj.org, CC license)
- Other joints, such as shoulder , elbow (inner side) , the upper joint between the two forearm bones (see picture)  hip (a cyst appears in the groin) , or ankle (inner or outer) , armpit (axilla) , jaw (a lump arises from the temporomandibular joint and appears in front of the earlobe) 
- A disc in the lumbar spine (mostly in young men), which can cause sciatic pain (sciatica) 
- The femur (the bone in the thigh)  or humerus (the bone in the upper arm) 
- The quadriceps muscle in the thigh  or the gastrocnemius muscle in the calf 
Symptoms and Signs
Some ganglion cysts are hidden within the joints (occult cysts) and are not visible or palpable and may or may not cause symptoms . An occult cyst on the wrist may show up when you bend the wrist . Common symptoms of ganglion cysts include [3,4,5,7,25,53]:
- A ganglion cyst appears as a lump, pea- to plum-sized, covered with normal skin. A cyst may become bigger with joint activity and smaller with joint rest and may rupture when you hit it accidentally.
- On palpation, a cyst can be soft or firm, movable or fixed, tender or not.
- Often a cyst causes a constant dull ache in the joint. Pain from the wrist may radiate up to the arm .
- A cyst can cause stiffness and limited motion, snapping, catching or locking of the affected joint and may affect hand gripping or walking .
- When a cyst on the palmar side of the wrist presses upon the median nerve, it may cause tingling in the thumb, index and middle finger (carpal tunnel syndrome); when it presses on the ulnar nerve, it may cause tingling in the pinky and ring finger (Guyon’s canal syndrome).
- When a cyst is attached to a tendon, it may cause muscle weakness in the affected finger or toe.
- A ganglion cyst arising from the hip joint may appear as a groin mass, which may pulsate, and when it presses upon the femoral nerve, it can cause groin pain or tingling [50,51].
Pathology and Pathophysiology
A ganglion cyst may originate from [3,4,29]:
- A tendon, which is a band of connective tissue that joins a muscle to a bone
- A tendon sheath
- A ligament, which is a band of connective tissue that connects bones in joints
- A joint capsule [3,4]
- Rarely, ganglion cysts develop within the bones, most commonly on the wrist bones , but also in the femur  or humerus , cartilaginous discs in the spine , muscles (mainly in the calf) [33,34] or nerves [17,35].
Picture 9. A ganglion cyst arising from the tendon sheath on the wrist
A ganglion cyst is like a balloon on a stalk filled with a translucent, jelly-like fluid. This fluid may originate from the synovial fluid normally present in the joint . A cyst can be rounded or oval, and it can be small, like a pea, or large, like a golf ball. You can have one or multiple cysts in one joint or in more joints at the same time . Cysts do not spread from one area to other, though .
The fluid from the joint may move into the cyst but not vice versa, so this is why a cyst can grow larger with the joint activity .
Histology and Cytology
The wall of the cyst is made of collagen (a type of protein) and fibrocytes (cells that produce collagen) . There are no epithelial cells on the inside of the cyst wall, so ganglion cysts are not true cysts but pseudocysts . The fluid within the cyst is made predominantly of water, hyaluronic acid, glucosamine, mucin and proteins [25,46]. There is usually no or only little tissue inflammation in and around the cyst . A ganglion cyst is rarely calcified [43,44].
Causes and Risk Factors
The exact cause of ganglion cysts is not known. The prevailing opinion is that ganglion cysts are caused by degeneration of the connective tissues in the joint, probably due to chronic irritation or minor trauma, such as pressure from the shoes or landing on the hand with an extended arm [7,11].
Risk factors include [3,5,7,18,25,31]:
- Age 15-40 years, especially in women (rarely in children under the age of 10) 
- Repetitive strain injury of the joints, for example in gymnasts or athletes, or repetitive wrist use in computer users  and guitar players 
- Tendon injury
- Some people believe a ganglion cyst can develop in association with the De Quervain’s tendonitis (inflammation of the tendons at the base of the thumb), which, when it occurs in mothers who take care of their newborns, is called “mother’s wrist” .
- A single trauma may result in the development of a traumatic ganglion cyst.
- Some orthopedics believe shoes with high heels increases the risk of a ganglion cyst in the foot .
A doctor observes and palpates the cyst and shines through it by using a penlight (transillumination). Most ganglion cysts are translucent, while most tumors are not (Video 1) [3,7]. In most cases, a doctor can make a diagnosis of a ganglion cyst by a physical exam alone .
Picture 10. Transillumination of a ganglion cyst (mucous cyst) on the finger
In doubtful cases, a doctor may check the content of the cyst by aspiration a small amount of fluid using a needle and syringe. When the obtained fluid is not clear as expected, it can be sent to the laboratory and investigated under the microscope (cytological investigation) .
- Ultrasound is a quick and cheap procedure, which can reliably show a ganglion cyst [3,5].
- Magnetic resonance imaging (MRI) or computed tomography (CT) can reliably show a ganglion or mucous cyst but are rarely needed [3,5,13].
- X-ray does not show a ganglion cyst but can rule out tumors and bone spurs .
Abnormalities that can resemble a ganglion cyst [11,13,31,43]:
- Benign tumor, such as neuroma, lipoma, fibroma, chondroma, schwannoma, hemangioma, osteoma
- Epidermoid cyst
- Plantar fibromatosis
- Rheumatoid nodule (in rheumatoid arthritis or systemic lupus erythematosus)
- Viral wart
- Keratinous horn
- Foreign body granuloma
- Abscess (a collection of pus)
- Xanthomas (lipid deposits in individuals with hypertriglyceridemia), which are yellow
- Bone spur or osteophyte (hard)
- Bone cyst (hard)
- Gouty tophus (in the big toe, usually very painful)
- Ulnar or radial artery aneurysm (pulsating)
- Adventitious bursa (soft)
- Calcific tendonitis
- Giant cell tumor (a noncancerous but aggressive tumor) (hard)
A lump in the neck is rarely a ganglion cyst; it is more likely an abscess (after infection in the mouth or throat), enlarged lymph node or a thyroid nodule, goiter or cancer.
Ganglion vs Cancer
Ganglion cysts are translucent when you shine a light through them, but cancers and benign tumors are not.
A ganglion cyst disappears spontaneously without treatment in up to 58% cases [3,4,25,26].
When a cyst hurts, over-the-counter (OTC) painkillers, such as aspirin or ibuprofen, may help. Holding an ice pack (wrapped in a cloth, not directly to the skin) over the cyst for 20 minutes few times a day may also provide pain relief.
Wrist Braces or Splints
Wrist brace or splint prevent wrist mobility and may reduce pain and may, eventually, lead to a reduction of the cyst size .
A doctor may press upon a soft cyst with fingers until it bursts [19,25]. Doctors rarely use this method nowadays. Do not try to pop a cyst by yourself because you may cause damage to the nearby nerves .
Puncture of the Cyst
A puncture (acupuncture) of the cyst is rarely performed nowadays; a doctor pushes a suture perpendicularly into the wrist, and the cyst is allowed to drain for several days [7,19,25].
Video 1. Puncture of the cyst
Aspiration is mainly used to treat cysts on the back of the wrist (Video 2) and in the foot . A primary doctor or orthopedic surgeon cleans the skin above the cyst, injects a local anesthetic near the cyst and drains the cyst fluid by using a needle and a syringe. After aspiration, a doctor may inject a steroid into a cyst — this is supposed to reduce the chance of the cyst recurrence, but this has not been proven . Cysts on the palmar side of the wrist may be guided by an ultrasound to avoid injury of the radial artery . A doctor will place a bandage over the puncture, and you can leave the hospital right away and continue with your activities. The procedure may require you to stay in a doctor’s office for about 30 minutes.
In about half of the cases, after aspiration, the cyst will be filled with fluid in some time . When a cyst is aspirated 3 times, in about 80% cases it will be cured permanently [4,5]. Splinting the wrist after the cyst aspiration has not been proven beneficial and may actually prolong the stiffness of the wrist . According to one study, immobilization after cyst aspiration does not reduce symptoms or prevent cyst recurrence .
Video 2. Aspiration of a dorsal wrist ganglion cyst:
local anesthesia and aspiration
Surgery — Ganglion Cyst Removal (Ganglionectomy)
Cyst excision, which is usually an outpatient procedure, which lasts about 15 minutes, involves removing the cyst, its stalk and often a part of the tendon sheath or joint capsule from which the cyst originates with the scalpel  or laser [19,56]. A surgeon will close the wound with sutures and wrap the operated area with a bandage. You can usually go home in few hours after the procedure .
- In open surgery, an orthopedic surgeon makes about 2 inches (5 cm) cut through the skin and removes the cyst (Video 3) .
- In an arthroscopic or keyhole surgery, an operator pushes a thin endoscope with a camera and instruments at the end through a small incision in the skin into the joint and removes the cyst . Arthroscopic surgery usually results in less pain after a procedure and a shorter scar than open surgery [3,36].
Surgery can be performed under local or regional anesthesia (you are awake during the procedure) or general anesthesia (you fall asleep) .
Video 3. Surgical removal of a ganglion cyst from the top of the wrist: preparation, excision, sutures, bandage.
Recovery After Wrist Ganglion Surgery
You might need to wear a sling or splint for 3-7 days after an operation to avoid an injury to a surgical wound and to give time for swelling to go away . A bruise, swelling and tenderness in the operated area may persist for few days. At around day 10 after surgery, you will need to have stitches removed. Do not lift any objects heavier than a pound before sutures are removed . Pain on the wrist may persist for several weeks . Persistent swelling or joint stiffness may require physiotherapy. The incision leaves a permanent scar, which can be thick, red and numb, and, in some individuals, a small area around the scar will also be permanently numb .
- In the first 3 days after an operation, holding an ice pack over the wound dressing (NOT directly on the skin) may reduce swelling.
- Recovery time after wrist ganglion removal may range from few days to 6 weeks, depending on how extensive the surgery was and how much you use wrists during work [3,4,23].
- You may be able to drive after 2-4 weeks .
- A doctor or physiotherapist may suggest you specific exercises to maintain the mobility of the joint and massage of the scar to prevent adhesions.
- A surgical wound may need about 2 months to heal completely.
- After removal of a cyst from the top of the foot or big toe, you may be able to walk straight away.
- After removal of a cyst from the bottom of the foot, you might need to wear an offloaded surgical shoe for 2-3 weeks.
- Do not smoke during the recovery. Nicotine causes narrowing of the blood vessels and may greatly prolong healing of the surgical wound.
The Cost of Surgery
The cost of ganglion cyst removal surgery may vary greatly and depends on the hospital, the type of anesthesia used and the difficulty of operation. In the United Kingdom, the cost (as of September 2013) may range from 1,300 to 1,750 £ (British pounds).
Prognosis and Complications During and After Surgery
Possible complications of the ganglion cyst surgery [4,7,25,26]:
- Damage to the radial artery during operation of the cyst on the palmar side of the wrist
- Damage to the median or ulnar nerve on the wrist resulting in carpal tunnel or Guyon’s canal syndrome with numbness or tingling (paresthesia) in fingers
- Infection of the joint or surgical wound
- Allergic reaction or other side effects of anesthesia
- Permanent pain and stiffness of the joint
- Decreased range of motion in the joint, decreased grip strength
- Neuroma — a benign tumor that develops from the nerve
- Recurrence of the cyst in 10-48% of cases, much more likely after the removal of the volar than dorsal wrist cysts 37. When the associated part of the synovial sheath from which the cyst arises is removed as well, the recurrence rate may be as low as 4%. According to one study, a volar wrist ganglion cyst can recur as early as in one month or as late as after 12 years .
- A surgery leaves a scar, which can be sometimes thick and red (keloid) or tender .
- Laser surgery may result in less bruising and scarring than a surgery by a scalpel .
Arthroscopic surgery results in less pain and a smaller scar than open surgery, but the recurrence rate is about the same in both types [7,36].
Natural Home Remedies
What can you do:
- If you have a cyst on foot, you can try new, more comfortable shoes.
Do not do this:
- Do not pop a cyst with a needle, since you may not be sure if it is a cyst at all, and because you can cause a cyst infection .
- Do not try to burst a cyst by slamming it with a heavy object like a book because you can cause damage to the nearby nerves .
Homeopathic and Holistic Treatment
There is a lack of scientific evidence about the effectiveness of homeopathic or holistic methods in the treatment of ganglion cysts.
The exact cause of ganglion cysts is not known, so currently, no prevention guidelines exist. If you practice yoga you should avoid certain positions with leaning on your hands. Avoiding shoes with high heels may help prevent cysts in the foot.
- A ganglion cyst often disappears spontaneously.
- Aspiration usually results in symptoms relief, but the cyst may return in up to 50% cases.
- Surgical removal is currently the most effective cure for a ganglion cyst, but it leaves a scar, stiffness and pain in the joint may persist or even worsen, and the cyst may return in 4-48% cases.
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