The cause of a hand or wrist mass can be determined by the appearance of the mass, examination findings, and possibly by imaging studies, including x-ray or MRI. Definitive diagnosis requires examination of the mass by a pathologist, either after a biopsy or removal of the mass. The treatment your doctor recommends will depend on the cause of the mass.
The Most Common Hand and Wrist MassesGanglion Cysts
A ganglion cyst is the most common type of mass, representing about 50% of all hand and wrist lumps and bumps. The tough lining of the small joints of the wrist forms a small pouch, and joint fluid collects within it. Ganglion cysts can also form as pouches off a tendon sheath or a knuckle joint; these are called mucous cysts.
Giant Cell Tumor of Tendon Sheath
A giant cell tumor of tendon sheath is not a true tumor, but rather a firm mass. These masses can arise from a tendon sheath or from joint lining (synovium). Giant cell tumors of tendon sheath tend to grow slowly and can become painful. The problem with these masses is that, while they are usually easily removable, they often come back.
An inclusion cyst occurs after an injury to the hand or finger, often years later. When a penetrating injury occurs, such as a deep cut, surface cells can be pushed into the deep layers of the palm or finger. This may cause the formation of a cyst in this area. Patients often do not even remember the initial trauma that eventually leads to the inclusion cyst.
A carpal boss isn't a tumor, but an overgrowth of bone on the back of the hand that's similar to a bone spur. It may be misdiagnosed as a ganglion cyst, but a carpal boss is more firm and unable to be moved. Patients with a carpal boss often notice a bump, but they are seldom bothered by it. If the bump does become problematic, removal of the bone is possible.
An enchondroma occurs when cartilage grows inside the bone. This is a noncancerous tumor. An enchondroma becomes a problem when the tumor weakens the bone, which may lead to a pathologic fracture. Very rarely (about 1%) of enchondromas develop into a cancerous tumor over time.
Could it be cancer?The most common types of cancer of the hand and wrist are skin cancers including:
When a cancer does occur under the skin in the hand or wrist, it can also be due to a metastasis (cancer that has traveled from elsewhere in the body). The most common type of cancer to metastasize to the hand or wrist is lung cancer.
DeGroot, H "Initial Evaluation of Tumors of the Hand" BoneTumor.Org.