CRP-22

CRP-22

Clinical History

The patient is a 20 year old female. Positive ANA; SLE clinically. BUN 40, creatinine 2.6, albumin 1.3. BP. 140/70.

Gross Description

Received in transport media are two core of renal tissue measuring 11 and 12 mm in length and 2 nun in diameter. A 1-mm fragment is taken from each core for EM. The remainder of the 11-mm fragment is submitted for immunofluorescence, and the remainder of the 12-mm fragment is submitted for light microscopy.

Pathology

Case CRP-022 Trichrome

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consist of a fragment of renal cortex with a small portion of medulla on one end. There are at least 35 glomeruli in the sections. About 40% of the glomeruli contain epithelial crescents of varying size. No fibrous crescents are present, although a few crescents are beginning to show early infiltration by fibroblasts and formation of new collagen. All of the glomeruli show varying degrees of hypercellularity. In some of the glomeruli the cellular proliferation is diffuse, while in other the lesion is more segmental. In the glomeruli with more segmental proliferation, the peripheral capillary loops are generally quite thickened and eosinophilic, suggestive of large subendothelial deposits (wire loops). A few small foci of necrosis with karyorrhexis are identified in some glomeruli. Some of the peripheral capillary loops are completely occluded by large masses of eosinophilic material, probably representing immune complex deposits. There is diffuse interstitial edema, although interstitial fibrosis appears to be mild and patchy. The interstitium contains numerous lymphocytes. Most of the tubules are well preserved, although a few show dilatation and epithelial simplification. The small arteries in the biopsy show no significant thickening, and the arterioles are unremarkable.

Immunofluorescence

There are fourteen glomeruli in the sections. Many of these contain thickened capillary basement membranes consistent with wire loop lesions. There is diffuse capillary and mesangial staining that is graded 4+ for IgM, IgA, C3 and kappa light chain. There is similar staining that is graded 2+ for IgG, Clq and lambda light chain. Tubular basement membranes show l+ granular staining for IgG, IgA, Clq, C3 and kappa light chain. There is strong nuclear staining of the tubuloepithelial cells for IgG and kappa and lambda light chains. There is no staining of the vessels.

Electron Microscopy

Two thick sections are available, but one contains no glomeruli. The other contains six glomeruli, and all are markedly abnormal. They show segmental hypercellularity and very thick capillary basement membranes. Ultrastructural examination confirms the thickening of the capillary basement membranes, and a number of examples of mesangial interposition are noted. Numerous subendothelial electron dense deposits are present in many of the peripheral loops, and some of them are massive. There is diffuse effacement of the visceral cell foot processes. Mesangial areas are markedly expanded by increased matrix and cells, and they also contain numerous electron dense deposits. Occasional small intramembranous and subepithelial deposits are identified. Tubular basement membranes contain occasional small electron dense deposits.

Diagnosis and Comments

Kidney, needle biopsy- Diffuse proliferative lupus glomerulonephritis. WHO class IV.

These findings are most consistent with diffuse proliferative lupus glomerulonephritis. This appears to be an early lesion, since there is minimal interstitial or tubular damage in this biopsy, and no glomerulosclerosis was identified.

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