Ethosuximide-induced lupus-like syndrome with renal involvement.

A 20-year-old man developed fever and urinary abnormalities with positive antinuclear antibody (ANA) two months after the start of ethosuximide. A renal biopsy showed mild mesangial cell proliferation and cellular crescents predominantly occupying a vascular pole in 7 out of 80 (8.8%) glomeruli. In the arteriole, mainly in close proximity to the glomerulus, proliferation of smooth muscle cells and luminal narrowing were observed. Discontinuation of ethosuximide led to the disappearance of fever, ANA and urinary abnormalities. These findings are strongly suggestive of a causal relationship between ethosuximide and a lupus-like syndrome with peculiar renal involvement.