Tophus
Tophi (plural of tophus) usually appear as lumps on the skin over affected joints due to deposits of monosodium urate crystals in patients with longstanding high levels of serum uric acid (hyperuricemia). Tophi are a pathognomonic feature of gout.
Clinical presentation
Tophi are firm, yellow, painless lesions 1. In addition to being found on the skin over joints, they may also be found formed over the olecranon, prepatellar bursa, and the helix of the ear 1.
History and etymology
Tophus means "stone" in Latin.