CRP-14

CRP-14

Clinical History

The patient is a 62 year old male. Acute renal failure, abnormal chest x-ray, and 4 to 5 month history of "sinusitis." Creatinine was 1.0 on 8/15/01 and has risen to 4.5 with BUN of 150. Nondiagnostic skin biopsy, nondiagnostic open lung biopsy and nondiagnostic sinus biopsy. C-ANCA 1:320, ANA 1:40 speckled. Anti-GBM pending.

Gross Description

Received in transport medium is one wedge-shaped fragment measuring 17 x 5 mm in greatest dimension. An 8-mm fragment is taken for immunofluorescence, seven 1-mm pieces are taken for EM, and the remaining tissue is submitted for light microscopy.

Pathology

Case CRP-014 Trichrome

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consists of two fragments of superficial renal cortex that contain eighty-one glomeruli in the three levels. Four of these are globally sclerotic, but none show segmental sclerosis. About 70% of the glomeruli contain segmental necrotizing lesions, and fifty-one glomeruli (63%) contain cellular crescents. Some of these crescents have ruptured through Bowman's space and are associated with periglomerular inflammation. The remaining uninvolved glomeruli show minimal mesangial expansion and no significant proliferation. The capillary basement membranes in these glomeruli are unremarkable with the silver stain. The PASH and trichrome stains show diffuse interstitial edema and at least mild interstitial fibrosis. However, there is only mild focal tubular atrophy. Occasional small collections of lymphocytes are present in the interstitium, and some of these are associated with mild tubulitis. The vasculature is well sampled. There is mild medial thickening and focal intimal fibrosis in the small arteries. There is no vasculitis, and no thrombosis is identified.

Immunofluorescence

There are twelve glomeruli in the sections. At least two of these contain cellular crescents. There is 2+ focal and segmental staining for C3, and there is trace focal and segmental staining for IgG, IgA and kappa. There is no glomerular staining for IgM, Clq, albumin or lambda. There is 2+ staining for C3 in the vessels. There is no staining of tubular basement membranes.

Electron Microscopy

Three thick sections containing a total of four glomeruli are available. One is obsolete, and two contain cellular crescents. Ultrastructural examination reveals compression of the glomerular tufts with marked segmental wrinkling of the capillary basement membranes. The foot processes over these loops are completely effaced. There is fibrin deposition in Bowman's space in association with the crescent. The uninvolved capillary loops show no significant thickening, and the foot processes are intact. No immune complex deposits are identified in the mesangium or along the capillary basement membranes.

Diagnosis and Comments

Kidney, needle biopsy. Pauci-immune crescentic glomerulonephritis, consistent with Wegener's granulomatosis.

This pattern of pauci-immune crescentic glomerulonephritis is very typical of Wegener's granulomatosis, although an identical pattern may be seen in microscopic polyangiitis. The positive C-ANCA, as well as the clinical history of sinus involvement, is much more consistent with Wegener's than microscopic polyangiitis. Although there is mild tubulointerstitial scarring, significant recovery of renal function appears possible if the glomerular injury can be controlled.

Renal failure is the severe reduction of renal function and often leads to reduced urinary output.

Blood urea nitrogen (BUN) is used as a measure of the glomerular filtration rate and is increased in renal failure.