A hard lump has appeared on the joint of the back of the hand.

Lumps appearing on the joints of the back of the hand may be caused by joint cysts, benign lipomas, rheumatoid arthritis, polyarteritis nodosa, or soft tissue sarcomas, and can be treated through daily care or medication. Specific analyses are as follows:

1. Joint Cysts: Joint cysts are a type of cyst that develops around joints and are typically filled with fluid. They may form a firm, sac-like lump on the joints of the back of the hand. Joint cysts generally do not cause severe pain or functional impairment, but patients should avoid strenuous physical activity to prevent secondary injury.

2. Benign Lipoma: A benign lipoma is a common soft tissue tumor and is usually harmless. A hard lump on the back of the hand may result from excessive proliferation of fat cells. Benign lipomas grow slowly and typically do not cause pain or other serious symptoms.

3. Rheumatoid Arthritis: Rheumatoid arthritis may cause symptoms such as joint pain and swelling. The hard lump on the back of the hand could be one manifestation of this condition. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be used under a doctor's guidance, including medications such as meloxicam tablets or indomethacin tablets.

4. Polyarteritis Nodosa: Polyarteritis nodosa is a rare autoimmune disease that primarily affects small blood vessels. This condition may lead to symptoms such as pain, swelling, and hard nodules in areas like the fingers and wrists. Patients may be prescribed corticosteroids under medical supervision, such as hydrocortisone tablets or prednisone tablets.

5. Soft Tissue Sarcoma: Soft tissue sarcoma is a malignant tumor that may grow rapidly, causing pain, swelling, loss of function, and other systemic symptoms. A hard lump on the back of the hand could indicate a malignant tumor. Immediate medical attention is required, and treatment may involve surgery, chemotherapy, or other interventions.

Patients are advised to consult a doctor early for an accurate diagnosis and appropriate treatment.