Differential Diagnosis for a Small Nodule on the Thumb Side of the Wrist
Single Most Likely Diagnosis
- Ganglion cyst: This is the most common benign lump found on the wrist, often appearing on the thumb side. It is a fluid-filled sac that can cause discomfort or pain, especially when it presses on nearby nerves.
Other Likely Diagnoses
- Wart or other skin lesion: A small nodule on the wrist could be a wart, a benign growth caused by the human papillomavirus (HPV), or other types of skin lesions like a keratoacanthoma or a seborrheic keratosis.
- Lipoma: A lipoma is a benign tumor composed of fat tissue. It can appear as a small, movable nodule under the skin and can occur almost anywhere on the body, including the wrist.
- Benign bony growth: Such as an osteochondroma, which is a type of benign bone tumor that can cause a lump on the wrist.
Do Not Miss Diagnoses
- Gout or pseudogout: Although less common, deposits of uric acid crystals (gout) or calcium pyrophosphate dihydrate crystals (pseudogout) can cause nodules or lumps around the joints, including the wrist. Missing these diagnoses could lead to inadequate treatment of a potentially debilitating condition.
- Rheumatoid nodule: In patients with rheumatoid arthritis, nodules can form over bony prominences, including the wrist. These are significant because they indicate active disease and may require adjustment of treatment.
- Infection or abscess: A small nodule could be the sign of an underlying infection, including an abscess or a felon (an infection of the fingertip pad), which requires prompt antibiotic treatment or drainage.
Rare Diagnoses
- Sarcoma: A rare type of cancer that can appear as a lump under the skin. While extremely uncommon, sarcomas (such as a soft tissue sarcoma) are critical to diagnose early for effective treatment.
- Neurofibroma: A benign nerve sheath tumor that can occur as a solitary nodule. It's part of neurofibromatosis type 1 (NF1) in some cases, a genetic disorder that affects 1 in 3,000 people.
- Glomus tumor: A rare, benign tumor of the glomus body, a specialized form of blood vessel. It can occur under the fingernail or on the wrist and is known for causing significant pain disproportionate to its size.