Rapidly progressive silicon nephropathy.

Rapidly progressive renal failure developed in four patients with silica exposure. Three presented with manifestations of a connective tissue disorders. All had abnormal proteinuria, hypoalbuminemia and active urinary sediments. Histologically, a distinct constellation of findings was present, consisting of glomerular hypercellularity and sclerosis, crescents, interstitial cellular infiltrates and tubular necrosis with red cell casts as seen on light microscopy. On electron microscopy there was foot process obliteration, characteristic cytoplasmic dense lysosomes, microtubules and dense deposits. Despite vigorous treatment, two patients died of the systemic illness and one is on hemodialysis. The fourth is improved after pulse methylprednisolone therapy. We propose that silica induced this multisystem disease through activation of the immune system and a direct tissue toxic effect.