CRP-29

CRP-29

Clinical History

The patient is a 24 year old black male. History of lupus with recent sharp decline in renal function. BUN 54, creatinine 5.9, albumin 2.3. Urinalysis shows moderate blood and >300 mg/dl.

Gross Description

Received in Zeus fixative are three cores measuring 3, 8 and 15 mm in length and 1 mm in diameter, which are entirely submitted for immunofluorescence. Received in Carson's fixative are three cores measuring 9, 12 and 18 mm in length. Three 1-mm pieces are taken for EM, and the remaining tissue is submitted for light microscopy.

Pathology

Case CRP-029 Trichrome

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

Sections contain five cores of renal cortex with at least forty-five glomeruli. Three are globally sclerotic, but there are no segmental sclerotic lesions. The glomeruli show moderately increased mesangial matrix with mesangial and endocapillary proliferation. Ten glomeruli contain cellular crescents. About one-third of the glomeruli exhibit ischemic thickening and wrinkling of the capillary basement membranes. The silver stain shows focal double contours as well as spikes and bubbling along the basement membranes. No wire loops are identified. Three glomeruli exhibit mesangiolysis with capillary thrombosis. PASH and trichrome stains show edema with patchy moderate severe interstitial fibrosis and tubular atrophy. There is patchy mild interstitial inflammation, and mild focal tubulitis is identified. The arterioles and small arteries are markedly thickened with obliteration of many of the lumina. There are abundant intimal and luminal deposits of glassy eosinophilic material, which is fuchsinophilic in the trichrome-stained section. The endothelium is swollen and denuded, and there is smudgy degeneration of myocytes, without inflammatory infiltration of the vessel wall. Several arterioles are occluded by fibrin thrombi, and there are red cell fragments in the swollen intima.

Immunofluorescence

fibrin thrombi, and there are red cell fragments in the swollen intima.

Immunofluorescence: There are twenty glomeruli per section. Four contain cellular crescents. There is diffuse granular staining in the mesangium and along the capillary loops that is graded 4+ for IgG and light chains and 1+ for C1q. There is focal segmental staining that is graded 1+ for IgM and C3. There is no glomerular staining for IgA or albumin. There is diffuse staining in the vessels that is graded 4+ for IgG and light chains and 1+ for C1q and C3. There is diffuse 2+ staining for IgG and light chains along the tubular basement membranes; there is also 2+ focal staining for IgM, C1q and C3.

Electron Microscopy

Three thick sections containing a total of six glomeruli are available. Three contain cellular crescents. Ultrastructural examination of three glomeruli reveals moderately increased mesangial matrix with numerous small mesangial deposits. The capillary basement membranes are moderately thickened and contain numerous subendothelial deposits. There is focal expansion of the subendothelial space with pale "fluffy" material. Rare small subepithelial deposits are also noted. The foot processes are completely effaced. Tubular basement membranes contain numerous deposits as well.

Diagnosis and Comments

Kidney, needle biopsy - Diffuse proliferative lupus nephritis with 24% crescents (WHO class IV. - Lupus vasculopathy. - Thrombotic microangiopathy.

This is an extremely active lesion, and the finding of lupus vasculopathy as well as thrombotic microangiopathy is associated with an even more ominous prognosis. Furthermore, there is already moderate tubulointerstitial scarring. However, only 6% of the glomeruli are globally sclerotic, so there is still some potential for recovery of renal function.

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

A normal PaCO2 is 35 to 45 mmHg.