Knuckle pads, also known as heloderma, meaning similar to the skin of the Gila monster lizard for which it is named, are circumscribed, keratotic, fibrous growths over the dorsa of the interphalangeal joints.

[6][7][8] From a clinical perspective, these are well-defined, non-compressible, freely moveable lesions that resemble warts and primarily affect the dorsal portion of the proximal interphalangeal (PIP) and, less frequently, the metacarpophalangeal (MCP) joints.

The differential diagnosis includes retained foreign objects, neurofibromas, rheumatoid nodules, gouty tophi, warts, xanthomas, synovial cysts, and Bouchards and Heberdens nodes.

[7] When a diagnosis is unclear, plain radiographs, histology (if sonography is not conclusive), and ultrasound improve the information-gathering process and lower the possibility of a misdiagnosis.

[18][19] A small number of treatments have shown promise recently, but they are frequently moderately to highly invasive and are primarily based on case reports.