The most frequent swelling or masses found at the hand and wrist level are ganglion cysts.
Ganglion cysts in the wrist are more frequent in women, but in the hand, ganglions form as a result of arthritis of the joints and this type of ganglion is called a mucous cyst. Ganglions are like a small balloon composed of the joint capsule, filled with a clear, colorless, gelatinous fluid that comes from the joint itself. They usually present with a single cavity but may contain multiple chambers. When ganglions occur, they usually come and go with activity but once present for more than four weeks, the likelihood of spontaneous resolution is unlikely. The reason is that the ganglion has a one way valve mechanism that allows for the fluid to come in from the joint but makes it difficult for the fluid to return to the joint. 70 % of ganglions occur between the second and fourth decades of life, while in older age groups, they may be associated with osteoarthritis and the spurs around the joint are usually responsible for their formation. Ganglions are rarely seen in children and when present is usually due to ligamentous laxity. 60-70 % of the wrist ganglions occur on the back of the wrist over the scapholunate ligament and about 20 % are found in the front or volar side of the wrist over the scaphotrapezoid joint. The differential diagnosis of the dorsal wrist mass is abnormal muscles of the hand (extensor digitorum brevis manus), synovitis of the extensor tendons (found in patients with rheumatoid arthritis) and other masses like lipomas (fat tumors), venous aneurysms, giant cell tumors, or other soft tissue tumors.
Patients complain of pain that is aggravated with repeated use of the hand, and witness a localized slow growing mass associated with mild aching and weakness about the area of its occurrence. On physical exam, cysts can be firm, smooth, rubbery, rounded, slightly fluctuant and at times tender. Cysts transmit the light of a penlight when in the dark. Usually cysts are fixed but may have slight mobility on exam and when a dorsal ganglion is present in the back of the wrist, it becomes more obvious when the wrist is bent (flexed). On occasion, patients will present with pain with maximal wrist extension, tenderness to palpation over the scapholunate joint but no obvious mass on inspection. This may represent an occult ganglion cyst and an MRI may be necessary for the diagnosis to be made. Ganglion cysts also arise from the tendon lining called tenosynovium and from the flexor or extensor sheaths by microdegeneration of this collagen substance.
When a ganglion is associated with an arthritic DIPJ(Distal InterPhalangeal Joint), it is called a Mucous Cyst, which is a pea-sized or smaller mass that is painful if struck. Individual patients and doctors without experience are sometimes tempted to drain it in the office. This is a mistake that will cause a sinus drainage and infection of the joint. When present, this is a surgical problem that needs to be addressed in the operating room. Other rigid masses in the region correspond to bony spurs of the arthritic joints and these do not have to be removed unless painful. Mucous cysts can create grooving of the nail plate (actual nail) when it extends far enough to reach the nail growth center called the germinal matrix of the nailbed.