Renal medulla in severe gout: typical findings on ultrasonography and dual-energy CT study in two patients

Monosodium urate (MSU) crystal deposition in renal medulla, described as early as the 1800s,1 was documented by autopsy studies in the 1950s to 1970s,2 3 and later by renal biopsies.4 Renal deposits have been reported mainly in patients with gout and rarely in non-gout patients with renal failure.4 Deposits appeared to be surrounded by inflammatory granulomas and medullary fibrosis. These observations led to the description of microcrystalline gouty nephropathy, a concept that was later challenged and even denied.5 Here, we report on two patients with severe gout and the use of modern imaging modalities to reveal widespread crystal deposition in the renal medulla. Patient 1 was a French 54-year-old man with Lesch–Nyhan syndrome; the gene defect was previously reported.6 The patient experienced several episodes of renal colic and had severe tophaceous gout, frequent flares, urate arthropathies and worsening dystonia. He was poorly adherent to urate-lowering drugs, and the uricaemia fluctuated over the years from rarely normal to frequently high (10–15 mg/dL). The patient took a beta-blocker for hypertension; the body mass …