There are many reasons a patient may get a mass on their hand. Fortunately, the vast majority of these masses or tumors are benign. Given the anatomy of the hand; however, even a very small tumor in the hand can cause severe symptoms where the same mass may not even be noticeable in another part of the body.
The most commonly seen masses in the hand are ganglion cysts. These are fluid filled sacs that can arise next to a joint or along a tendon sheath. The fluid can arise from a joint that is arthritic or alongside a tendon that is inflamed.
Giant Cell Tumor
The most common soft tissue tumor seen in the hand and fingers is the giant cell tumor. Despite the name “tumor” these masses are benign. These masses only rarely ever spread to other parts of the body. they do sometimes locally recur but can usually be removed again without difficulty. As these masses grow in size they can compress other structures and cause pain.
Most of the time these giant cell tumors occur in the soft tissue layers of the hand and fingers. Rarely giant cell tumors do occur within the substance of a bone or within a tendon sheath. These two presentations can make treatment more difficult.
An enchondroma is a benign tumor. The cells of origin are cartilage cells. Rather than growing on the outside of the bone in the joint space, the normal location of cartilage cells, these tumors grow inside the bone. They tend to grow during childhood. They are usually found incidentally when x-rays or other imaging studies are done for an unrelated issue. As an enchondroma grows it replaces the strong bone with a gelatinous substance which can weaken the bone. Experts disagree on how to best treat enchondromas. Many enchondromas can be treated non-operatively. When seen in the hand and arm, enchondromas are sometimes removed. Given the small size of the bones in the hand, wrist and arm it is easy to imagine how even a small tumor can significantly weaken the strength of the bone as it grows. Here you can see an enchondroma (black) that has replaced much of the bone in the finger and has ruptured through the cortex (outer lining) of the bone.