Gout is a metabolic disease of hyperuricemia in which crystals of monosodium urate are deposited in tissues. When deposited cutaneously, they are called tophi. Common locations of tophi include acral joints, extensor surfaces, and the helix of the ear. Less commonly, they can involve the finger pads and nails. Gouty tophi in the nail matrix or nail bed may cause onychodystrophy including longitudinal ridging and grooves in the nail plate. Hyperkeratotic lesions mimicking squamous cell carcinomas have also been reported. It is rare for tophi to involve the nails without evidence of additional tophi in more classic locations.

Individuals who are immunocompromised (such as from chronic kidney disease, diabetes mellitus, autoimmune disorders, and malignancies, including leukemia or lymphoma) may have an altered presentation of gout and an increased risk of complications, including bacterial infections complicating ulcerated tophi.