CRP-11

CRP-11

Clinical History

The patient is a 30 year old white woman with congenital hydrocephalus and a ventriculo-atrial shunt. The past medical history is notable for multiple urinary tract infections. The patient now has nephrotic syndrome with an active urine sediment. Creatinine - 10.7; creatinine clearance - 3 cc/min; 24 hour protein - 3.5 grams.

Gross Description

Received in transport medium are three needle cores that measure 15.0, 20.0 and 3.0 mm in length and 1.0 - 2.0 mm in diameter. Three 1.0 mm pieces are separated for ultrastructural studies, and the remainder is divided for light and immunofluorescence microscopy.

Pathology

Case CRP-011 Silver

Microscopic Description, Immunofluorescence, and Electron Microscopy.

Microscopic Description

Light Microscopy

Sections are of four needle core fragments of renal cortex. There are at least 72 glomeruli in the various levels, 47 of which are obsolete. The viable glomeruli show diffuse hypercellularity and accentuated lobularity of the glomerular capillary tufts. The increased cellularity is due to both proliferation of endogenous cells as well as infiltrating monocytes and neutrophils. There is prominent reduplication of the glomerular basement membranes on special stains. No necrotizing lesions and no crescents are evident. The tubulointerstitium shows advanced interstitial fibrosis and tubular atrophy, involving an estimated 80% of the tubulointerstitial mass, and there are diffuse, mixed inflammatory cell infiltrates. Some of the viable tubules contain free red cells; no red cell casts are evident. The vasculature is remarkable for thrombotic microangiopathy-type lesions involving the intralobular and arterioles. Few of the vessels have active thrombi, but many show marked swelling of the endothelium, with focal necrosis of the muscularis and/or mucoid degeneration. No vasculitic lesions are evident.

Immunofluorescence

Twenty-eight glomeruli are available for study, 9 of which a.re obsolete. There is diffuse, granular staining in a mixed mesangial and capillary loop pattern that grades: IgG, l+; IgM, 1-2+; Clq, trace-1+, C3, 1-2+; and kappa and lambda light chains, 1-2+ and trace, respectively. IgA is negative. The vasculature demonstrates focal and segmental C3 deposition. The tubules are unremarkable.

Electron Microscopy

Two glomeruli are present in the three tissue pieces processed for EM. They demonstrate marked proliferation of both mesangial cells and endocapillary cells, with multiple infiltrating monocytes and neutrophils. Mesangial regions are markedly expanded with increased matrix and cells and there are numerous, mesangial immune complex-type deposits. Glomerular basement membranes are markedly distorted and there is significant mesangial interposition and new deposition basement membrane material generating "reduplication". Subendothelial deposits are present in abundance. The visceral epithelium is in disarray and shows broad stretches of foot process effacement. Only rare small subepithelial deposits are identified.

Diagnosis and Comments

Kidney, site not specified, needle biopsy - Shunt nephritis with advanced nephrosclerosis

This biopsy demonstrates classical features of a shunt nephritis, marked by a diffuse proliferative, MPGN-type pattern of glomerular injury with subendothelial and mesangial immune complexes. There is advanced nephrosclerosis, with preservation of less than 20% of the tubulointerstitial mass. Notably, the glomerular and tubular interstitial changes are complicated by a thrombotic microangiopathy, the etiology of which is unclear.

An infiltrate is an accumulation of cells in the lung parenchyma--this is a sign of pneumonia.