Atheromatous emboli in renal biopsies. An ultrastructural study

In a series of 755 renal biopsies atheromatous emboli were found in biopsies of 8 men from 49 to 72 yr of age. Unexplained recent deterioration of renal function was present in each. This previously unreported incidence of 8/755 biopsies is ascribed to the selection for biopsy of patients with unexplained decrease in renal function. Hypertension was a major feature in 6, hyperlipidemia in 2, a leaking aortic aneurysm in 1, carcinoma of the pancreas in 1, and chronic glomerulonephritis in 1 patient. Toluidine blue stained epoxy sections proved to be more effective in recognizing small emboli than paraffin sections. Ultrastructural observation concerned early lesions (eg, fresh emboli with endothelial distortion or injury), intermediate lesions (eg, histiocytic or giant cell reaction and intimal proliferation), and later lesions (eg, extraluminalization of the crystals eventually resulting in inert location in intimal stroma). Osmiophilic deposits on the crystal surfaces were myelin form in structure and were felt to result from lysosomal action.