CRP-17

CRP-017

Clinical History

The patient is a 72 year old male. Acute renal failure of unknown etiology. Creatinine 5.5, BUN 75, urinary protein 371 mg/day. Normal complements, ANA, RA and SPEP. Patient has recently taken some Advil, but exact amount is unknown. Urinalysis shows 10 to 15 RBCs per high powered field, broad granular casts and no cellular casts.

Gross Description

Received in saline are six cores measuring 6, 7, 12, 14, 10 and 14 mm in length and 1 mm in diameter. Four 1-mm pieces are taken for electron microscopy. Three cores measuring 12, 13 and 8 mm in length are submitted for immunofluorescence, and the remaining tissue is submitted for light microscopy.

Pathology

Case CRP-017 Silver

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consists of three fragments of renal cortex that contain fifteen glomeruli in the three levels. None of these are obsolete, and none show segmental sclerosis. The glomeruli generally appear atrophic with thickened and wrinkled capillary basement membranes. However, two glomeruli demonstrate segmental necrosis ac the vascular pole, probably representing vasculitis of the afferent arteriole. There are no cellular or fibrous crescents. The PASH and trichrome stains show diffuse moderately severe interstitial fibrosis and tubular atrophy. There is tremendous acute interstitial inflammation. Most of the cells are polymorphonuclear leukocytes with a small percentage of eosinophils. This is associated with numerous examples of mild tubulitis. The most striking feature of the biopsy is the large vessels. Several show transmural inflammation with severe fibrinoid necrosis. Some of the vessels show rupture into the adjacent parenchyma, which is accompanied by severe interstitial inflammation. The arterioles are mildly thickened but are otherwise unremarkable.

Immunofluorescence

There are eleven glomeruli in the sections. None of these contain crescents. There is 1+ focal and segmental mesangial staining for IgM, Clq and C3. There is no glomerular staining for IgG, IgA, albumin or light chains. There is no staining of the tubular basement membranes or vessels. There is focal staining for C3 in Bowman's capsule.

Electron Microscopy

Three thick sections containing a total of two glomeruli are available. Ultrastructural examination of these two glomeruli reveals focal thickening and wrinkling of the glomerular basement membranes. The subendothelial space is widened and filled with pale, loose granular material. There is mild increase in mesangial matrix. The epithelial cell foot processes are completely effaced. No electron dense deposits are identified.

Diagnosis and Comments

Kidney, needle biopsy - Polyarteritis nodosa.

These features are most consistent with polyarteritis nodosa (macroscopic polyarteritis). This lesion is distinctly different from microscopic polyangiitis. In particular, ANCA serology is rarely positive in polyarteritis nodosa, and glomerulonephritis is rare. On the other hand, there are typically ischemic glomerular lesions, such as those described in this biopsy. Unfortunately, there is already moderately severe tubulointerstitial scarring. This scarring, in association with the severe necrotizing vasculitis, suggests that significant recovery of renal function is very unlikely.

Renal failure is the severe reduction of renal function and often leads to reduced urinary output.

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