Development of the gout tophus. An hypothesis.

Sequential stages have been demonstrated in the development of individual focal deposits of crystalline urate and associated cell infiltrates within subcutaneous gout tophi. The findings suggest that acini of macrophages are formed and that active cellular transport of urate from the interstitial fluid into the central zones of these structures accounts for the focal nature of crystallization within the tophus. This process seems to account for the formation of focal urate deposits up to some 1.5-2 mm in diameter. The corona then commonly disappears and adjacent deposits may fuse. These events may lessen the consequences of hyperuricemia.