CRP-56
CRP-56
Clinical History
The patient is a 50 year old male. Urinary protein 11 g/24 hr. Serum creatinine ranges from 1.0 to 1.2. ANA negative. No history of systemic illnesses.
Gross Description
Received in transport media are two cores measuring 10 mm and 12 mm in length and 1 mm in diameter. Three 1-mm pieces are taken for EM. The remaining 9-mm piece is submitted for immunofluorescence, and the remaining 10-mm piece is submitted for light microscopy.
Pathology
Case CRP-056 H&E
Case CRP-056 PASH
Case CRP-056 Silver
Microscopic Description
Light Microscopy
The specimen consists of a fragment of renal cortex that contains twenty-four glomeruli in the three levels. None of these are obsolete, and none show segmental sclerosis. However, all the glomeruli show varying degrees of mesangial expansion by acellular eosinophilic material. This material occasionally extends out along the capillary basement membranes. There is also striking thickening of the afferent arterioles by the same material. There is no hypercellularity. The silver stain shows long, thin, delicate spikes projecting from the mesangial surfaces as well as occasionally along the basement membranes. There is minimal patchy interstitial fibrosis, and there is no significant tubular atrophy. There are no inflammatory infiltrates. Most of the arterioles show small eosinophilic deposits within the walls. There is no significant intimal fibrosis or medial hypertrophy. A Congo red stain is positive in the glomeruli and most of the arterioles and small arteries.
Immunofluorescence
There are seven glomeruli in the sections. There is 2+ amorphous staining for lambda light chain in the expanded mesangial areas. There is trace amorphous mesangia1 staining for IgM and Clq. There is no staining for IgG, IgA, C3 or kappa light chain in the glomeruli. The tubular epithelium contains numerous protein droplets that stain for immunoglobulin, C3, albumin and light chains. There is no staining of the tubular basement membranes. There is focal C3 staining in the vessel walls.
Electron Microscopy
Three thick sections containing a total of six glomeruli are available. One is obsolete, but the other five are similar to those described above and show mesangial expansion by homogeneous acellular material. Ultrastructural examination reveals large fibrillary deposits within the mesangium and occasionally extending out along the endothelial surfaces of the capillary basement membranes. These fibrils are of indeterminate length and are randomly arranged. No immune complex deposits are identified in the glomeruli. The arterioles show similar fibrillary deposits.