Renal Pathology

Renal Pathology Virtual Microscopy Study Set

Renal Pathology Cases. These renal pathology cases were collected by William Cook, M.D., PhD as a teaching set for use by UAB pathology residents interested in renal pathology. Virtual Microscopy slides were curated and made available on PEIR by Dr. Peter Anderson and Bade Iriabho.

Clinical History

The patient is a 76 year old female.

Recently detected renal insufficiency, proteinuria and hypertension. BUN 50, creatinine 2.6, creatinine clearance 36 ml/min, urinary protein 3.5 g/24 hr. BP 150/90.

Gross Description:

Received in Zeus fixative is one core of renal tissue measuring 1.1 cm in length. This is entirely submitted for immunofluorescence. Received in Carson's fixative are two cores of tissue measuring 8 mm each. Two 1-mm fragments are taken for EM, and the remaining tissue is processed for light microscopy.

Pathology

Case RP-001 Silver

Microscopic Description, Immunofluorescence, and Electron Microscopy.

Microscopic Description:

LIGHT MICROSCOPY:

The specimen consists of two fragments of renal cortex that contain at least 36 glomeruli. Four of these are obsolete. The remaining glomeruli are all similar and show striking diffuse proliferation with accentuation of the normal lobular pattern. Many of the extra cells in the glomeruli are polymorphonuclear leukocytes. Because of the marked mesangial and endocapillary proliferation, Very few capillary loops are still patent. Silver and PASH stains show thickening of the capillary basement membranes, and examples of double contours consistent with mesangial interposition are identified with the silver stain. The trichrome stain shows reddish-orange subendothelial deposits in some of the loops, which probably represent immune complex deposits. No segmental sclerosis or necrosis is identified, and there are no epithelial crescents. There is diffuse mild interstitial fibrosis, and there is focal mild tubular atrophy. However, many of the tubules still show very good preservation. Occasional lymphocytes and plasma cells are scattered throughout the interstitium, but no large collections of inflammatory cells are present. There is no tubulitis. The small arteries in the biopsy show minimal intimal fibrosis, and there is no evidence of vasculitis.

Immunofluorescence:

There are sixteen glomeruli in the sections. None contain epithelial crescents or foci of segmental sclerosis. There is diffuse, coarse, granular staining along the capillary loops that is graded 4+ for C3, 2+ for IgG and light chains, and l+ for IgA. There is also focal and segmental l+ staining of the capillary loops for Clq. There is staining of similar intensity in the mesangial regions for all of these reagents. There is no staining in the glomeruli for IgM. Tubular epithelium contains occasional albumin droplets. There is no staining of the tubular basement membranes. There is no staining of the vessels

Electron Microscopy:

Two thick sections are available. One contains two glomeruli, but the other contains only a portion of a glomerulus on one edge. These are similar to those described under light microscopy and show striking diffuse hypercellularity with compromise of the capillary lumina. Many of the capillary lumina are completely ·filled with polymorphonuclear leukocytes. Capillary basement membranes are generally of normal thickness, but there is focal thickening with mesangial cell interposition. There is diffuse effacement of the visceral epithelial foot processes. Numerous subendothelial electron dense deposits are identified, and occasional small mesangial electron dense deposits are also noted. Subepithelial deposits are easily identified, and some are extremely large ("humps").

This pattern of diffuse proliferative glomerulonephritis is not specific and may occur in association with a number of systemic diseases, including autoimmune diseases, infections, and chronic liver disease. The presence of so many neutrophils in conjunction with large subepithelial deposits is most consistent with acute postinfectious glomerulonephritis. Although acute postinfectious glomerulonephritis is most typically associated with streptococcal infections, the MPGN-like features of the lesion (focal mesangial interposition, subendothelial deposits) suggests a chronic infection. The most common chronic infections associated with this type of glomerulonephritis include hepatitis B or C, visceral abscess, and mycoplasma.

Diagnosis and Comments

Kidney, needle biopsy · Diffuse proliferative glomerulonephritis, consistent with acute postinfectious glomerulonephritis (see description).

T71000 KIDNEY, P11430 BIOPSY, NEEDLE, M46812 GLOMERULONEPHRJTIS, PROLIFERATIVE, DIFFUSE M40000 GLOMERULONEPHRITIS, T71200 GLOMERULUS

Aortic insufficiency refers to the inability of the aortic valve to close properly, thus allowing regurgitation of blood into the left ventricle during diastole -- i.e., volume overload. Disease of the aortic valve leaflets is a common cause of insufficiency.

Protein in the urine is indicative of glomerular dysfunction.

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

The normal fibrinogen level is 184 to 412 mg/dL.

Autoimmune disorders involve an immune response directed at the host's own cells.

An abscess is a collection of pus (white blood cells) within a cavity formed by disintegrated tissue.