A ganglion cyst is a tumor or swelling on top of a joint or the covering of a tendon (tissue that connects muscle to bone). Also known as a bible cyst, is a swelling that often appears on or around joints and tendons in the hand or foot. It looks like a sac of liquid (cyst). Inside the cyst is a thick, sticky, clear, colorless, jellylike material. Depending on the size, cysts may feel firm or spongy.

• The size of the ganglion cyst can vary over time. It is most frequently located around the dorsum of wrist and on the fingers. The term "Bible bump" comes from a common urban legend that treatment in the past consisted of hitting the cyst with a Bible or another large book
• One large cyst or many smaller ones may develop. Multiple small cysts can give the appearance of more than one cyst, but a common stalk within the deeper tissue usually connects them. This type of cyst is not harmful and accounts for about half of all soft tissue tumors of the hand.

The exact cause of ganglion cyst is not known. But the most accepted theory suggests that it is caused by trauma to the joint which leads to that trauma causes the tissue of the joint to break down forming small cysts, which then join into a larger, more obvious mass. The most likely theory involves a flaw in the joint capsule or tendon covering (sheath) that allows the joint tissue to bulge out.

Ganglion Cyst Symptoms and Signs

• The ganglion cyst usually appears as a bump (mass) that changes size. Ganglia can form around any joint, but they are most frequently found in the wrist and ankles. They are usually painless and often barely visible as localized swellings
• Most ganglion cysts cause some degree of pain, usually following acute or repetitive trauma, but up to 35% are without symptoms, except for appearance.
• The pain is usually nonstop, aching, and made worse by joint motion. When the cyst is connected to a tendon, you may feel a sense of weakness in the affected finger.