CRP-48

CRP-48

Clinical History

The patient is a 76 year old female. History of bloody diarrhea and dehydration. No history of radiocontrast agents or aminoglycosides. Creatinine has recently risen to 7.6, and BUN is 39.

Gross Description

Received in Zeus fixative are two cores measuring 4 and 5 mm in length and 0.5 mm in diameter. These are entirely submitted for immunofluorescence. Received in Carson's fixative are two cores measuring 4 and 5 mm in length and 0.5 mm in diameter. Two 1-mm fragments are taken for EM, and the remainder is submitted for light microscopy.

Pathology

Case CRP-048 PASH

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consists of two fragments of renal cortex that contain twenty glomeruli in the three levels. Five of these are obsolete, but none show segmental sclerosis. There is no significant mesangial expansion or proliferation. Capillary basement membranes are unremarkable with the silver and PASH stains. There is only mild patchy interstitial fibrosis, but there is moderate interstitial edema. There is no significant tubular atrophy. However, many of the tubules are dilated, and there is epithelial simplification, vacuolation and focal necrosis. The PASH stain shows loss of the brush border in many of the proximal tubules. Occasional mononuclear inflammatory cells are noted in the interstitium, but there is no tubulitis. Arterioles show mild thickening but otherwise are unremarkable.

Immunofluorescence

There are only one to three glomeruli in the sections. All of these show normal morphology by light microscopy. There is no staining in the glomeruli for IgG, IgM, IgA, Clq, C3 or light chains. There is strong antinuclear staining for C1q in the tubular epithelium. There is no staining of the tubular basement membranes or vessels.

Electron Microscopy

Two thick sections are available, and each contains one glomerulus. These are similar to those described above and show essentially normal morphology. Ultrastructural examination reveals no significant thickening of the capillary basement membranes, and the foot processes are well preserved. No deposits are identified in the glomeruli. Tubular epithelium shows focal vacuolation, degenerative changes and loss of the brush border.

Diagnosis and Comments

Kidney, needle biopsy - Acute tubular necrosis.

These findings are most consistent with acute tubular necrosis. There is no evidence for any type of vasculitis or primarily glomerulopathy. The minimal amount of interstitial fibrosis, as well as the lack of significant tubular atrophy, suggests that significant recovery may be possible in the kidney.

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