Nodular masses have developed in the periarticular tissue of the proximal and distal interphalangeal joints of the right hand of a 58-year-old man with a 10-year-history of gout. Which of the following choices best describes the characteristics of these masses?

A 58-year-old man with a 10-year history of gout and nodular masses in the periarticular tissue of the proximal and distal interphalangeal joints of his right hand has tophus formation, which is pathognomonic for chronic gout. Tophi are deposits of monosodium urate (MSU) crystals in tissue. Gouty arthritis is a heterogeneous group of disorders characterized by hyperuricemia, recurrent attacks of acute arthritis, formation of deposits of MSU (tophi), and uric acid urolithiasis. It is the most common inflammatory arthritis in men older than 30 years. Gout is a multifactorial inheritance caused by a combi­nation of genetic susceptibility and the effect of certain environmental factors (e.g., alcohol, eating red meats). Hyperuricemia is associated, but not synonymous, with gout because some patients with gout have nor­mal uric acid levels. Primary hyperuricemia with gout refers to hyperuricemia that is a consequence of a disorder in uric acid metabolism that results from (1) decreased excretion (most common mechanism), (2) increased production, or (3) a combination of the two. Secondary hyperuricemia associated with gout can be caused by the same mechanisms as primary gout. There are secondary associations with diabetes mellitus, alco­holism, polycythemia rubra vera, leukemia, multiple myeloma, diuretic therapy, and the treatment of dis­seminated carcinomas.