20217              MEDULLARY SPONGE KIDNEY

No clinical information is available.

The specimen is a slice of kidney which measures 13 cms in length.  The surface is grossly irregular and shows wide shallow depressions.  The cut surface shows a wide and irregular cortex not well demarcated from the medulla.  The calyces are moderately dilated and there are a few small calculi in the lower calyx.  Immediately adjacent to this area the renal papillae are pale and many small cysts about 1 mm in diameter are visible.  The mucosa of the pelvis and lower calyx is velvety and is chronically inflamed.  The papillae in the upper pole appear essentially normal.  There are streaks of haemorrhage with interposed pyogenic inflammation between the medullary rays at all levels.  Histology shows in the pyramids large cystic dilations of tubules lines by columnar or cuboidal epithelium.  Some contain irregular calcific concretions.  There is very great surrounding irregular and diffuse proliferation of smooth muscle.  Outside this zone the tubules are small, narrow and sparse, and there is marked diffuse acute inflammatory reaction, with some foci of chronic inflammatory cells.  Glomeruli are lobulated and congested.  There is a wide zone of diffuse subcapsular fibrosis in which the scanty tubules contain pus.  Small arteries are somewhat thickened.