Capillarosclerosis of the lower urinary tract in analgesic (phenacetin) abuse. An electron-microscopic study.

The ultrastructural appearances in capillarosclerosis of the lower urinary tract in analgesic abuse are reported. The capillaries show thickened basement membranes consisting of numerous thin basement membrane lamellae. Between the newly formed basement membrane lamellae, masses of empty vacuoles (fat vacuoles) and a variety of membranous and vesicular structures are present. The pathogenesis of this alteration in the basement membrane is unknown. A common pathogenetic mechanism may be operative in the discoloration of renal papillae and mucous membranes of lower urinary tract on the one hand and capillarosclerosis on the other.