Intradermal tophi in gout: A case-control study

Objective. To describe the characteristics of intradermal tophi in patients with gout and search for factors associated with their development. Methods. This is a case-control study of patients with gout: cases (Group A , n = 21) had intradermal (not subcutaneous) plaques of monosodium urate (M SU) crystals located in sites distant to articular or paraarticular structu res, and controls (Group B, n = 42) had gout but no intradermal tophi. Both Group A and Group B were paired by sex, age (+/- 5 years), and duration of the disease (+/- 3 years). Analysis included serum and urinary uric acid l evels at first visit, radiographic stage of gout, the presence of associate d diseases, and previous therapy, specifically, chronic glucocorticoid and diuretic usage, Results. Intradermal tophi were located in the legs, forearms, buttocks, th ighs, arms, and abdominal wall. Patients in Group A had a greater number of nonintradermal tophi in common sites (11.9 +/- 12.5 vs 4.2 +/- 7.9, mean /- SD; p = 0.018), decreased glomerular filtration rate (46.74 +/- 25.11 vs 70.87 +/- 30.18 ml/min, p = 0.042), advanced radiographic changes (57.2 vs 7.1%; p = 0.0001), and longterm glucocorticoid self-medication (76 vs 36%; p = 0.006). We found no differences in other associated diseases between g roups. Conclusion, Intradermal tophi were commonly found in the legs and forearms, and less frequently in the buttocks, thighs, and abdominal wall of gouty p atients, and were associated with longterm self-prescribed glucocorticoids and chronic renal failure. The occurrence of intradermal tophi in these pat ients appeared to correlate with advanced disease.