CRP-25

CRP-25

Clinical History

The patient is a 34 year old female. BUN 8, creatinine 0.7, creatinine clearance 125 ml/min, and urinary protein 6.5 g/24 hr. BP: 116/75. Clinical Impression: Lupus nephritis.

Gross Description

Received in Zeus fixative is one core measuring 8 mm in length and 1 mm in diameter. It is entirely submitted for immunofluorescence. Received in Carson's fixative are two cores measuring 10 x 1 mm and 8 x 0.5 mm. Three 1-mm pieces are taken for EM, and the remainder is submitted for light microscopy.

Pathology

Case CRP-025 Trichrome

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consists of two small fragments of renal cortex that contain forty-five glomeruli in the three levels. One of these is obsolete, but none show segmental sclerosis. All of the glomeruli show moderate mesangial expansion and proliferation, and 11 of the glomeruli also show segmental endocapillary proliferation, focal necrosis, and occlusion of the capillary loops. There is one epithelial crescent, and one fibrous crescent is also noted. No definite wire loops are identified in the glomeruli. There is mild patchy interstitial fibrosis, and there is focal mild tubular atrophy. There are no inflammatory infiltrates. The arterioles and small arteries show mild focal thickening, but they are otherwise unremarkable.

Immunofluorescence

There are two to six glomeruli in the sections. There is diffuse coarse granular staining along the capillary basement membranes that is graded 4+ for IgG, IgA and light chains, and 2+ for Clq and C3. There is diffuse mesangial staining that is graded l+ for IgG, IgM, IgA, Clq, C3 and light chains. There are numerous albumin droplets in the tubular epithelium. There is no staining of the tubular basement membranes or vessels.

Electron Microscopy

Three thick sections containing a total of five glomeruli are available. These are similar to those described above and show moderate mesangial expansion and proliferation as well as marked thickening of the capillary basement membranes. There is also segmental endocapillary proliferation in three of the glomeruli, but there are no crescents. Ultrastructural examination reveals numerous large subepithelial and intramembranous electron dense deposits throughout the glomeruli. This is accompanied by diffuse effacement of the epithelial cell foot processes. Several small subendothelial deposits are also identified in one peripheral capillary loop. The mesangial regions are expanded by increased matrix and cells, and they also contain numerous large mesangial and paramesangial deposits.

Diagnosis and Comments

Kidney, needle biopsy - Focal proliferative and membranous lupus glomerulonephritis, WHO Class III + V.

These findings are most consistent with a mixed pattern of lupus nephritis. There appears to be long-standing membranous lupus glomerulonephritis, but there is now an additional much more proliferative component. The proliferation is still largely focal and segmental, rather than diffuse, which places this proliferative lesion in the WHO Class III category. Although the glomerular lesion is becoming much more active, there is only minimal tubulointerstitial scarring, and the vessels are still quite well preserved.

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

A normal gamma-glutamyl transpeptidase (GGT) is 0 to 65 U/L.

An occlusion is a blockage.

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