Chronic tophaceous gouty arthritis mimicking rheumatoid arthritis.

OBJECTIVES: To analyze the factors which differentiate chronic tophaceous arthritis from rheumatoid arthritis.

METHODS: We describe two cases of chronic gouty arthritis masquerading as rheumatoid arthritis. The characteristic features of each of these two conditions and the diagnostic approach are discussed in light of relevant literature.

RESULTS: The correct diagnosis was reached by the combination of accurate history taking (family history of gout, alcoholism, previous diuretic therapy and renal stones), guiding clinical features (subcutaneous tophaceous deposits) and specific radiological (assymetrical erosions with sclerotic margins and overlying edges) and laboratory findings (hyperuricemia and hyperuricosuria). It was confirmed by the identification of monosodium urate (MSU) crystals in the synovial and subcutaneous tissues.

CONCLUSIONS: Gout and rheumatoid arthritis rarely coexist. Chronic gouty arthritis may mimic rheumatoid arthritis, and vice-versa. Clinical suspicion supplemented by characteristic laboratory, radiological and histologic findings help at reaching an accurate diagnosis.