CRP-15

CRP-15

Clinical History

The patient is a 55 year old female with vasculitic lesions on her legs. Skin biopsy showed leukocytoclastic vasculitis. Normal renal ultrasound. Hematuria. BUN 21, creatinine clearance 86 ml/min, urinary protein 1.7 g/day. ANA negative.

Gross Description

Received in saline are two cores measuring 15 and 18 mm in length and 1 to 2 mm in diameter. Three 1-mm pieces are taken for EM. Two cores measuring 6 and 9 nun in length are submitted for immunofluorescence, and the remaining tissue is submitted for light microscopy.

Pathology

Case CRP-015 Silver

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consists of multiple small fragments of rental cortex that contain forty-five glomeruli in the three levels. Two of these are obsolete, and the remainder show moderate mesangial expansion and hypercellularity. In addition to the diffuse mesangial proliferation, however, eleven glomeruli also demonstrate segmental necrosis and neutrophilic infiltration, and five glomeruli contain cellular crescents. There are no fibrous crescents. The silver stain shows segmental rupture of the capillary basement membranes in the areas of necrosis, but there are no spikes along the loops, and no double contours are noted. The PASH and trichrome stains show very mild focal interstitial fibrosis. The tubules are quite well preserved, and there are no inflammatory infiltrates. The vasculature is well sampled and is unremarkable.

Immunofluorescence

There are thirteen glomeruli in the sections. One glomerulus has a cellular crescent. There is diffuse mesangial staining that is graded 3+ for IgA, 1+ for IgG, C3 and light chains, and trace for IgM. There is no mesangial staining for Clq. There is no staining along the capillary loops or tubular basement membranes for any reagent. Tubular epithelium contains albumin droplets. There is no staining of the vessels.

Electron Microscopy

Three thick sections containing a total of two glomeruli are available. Ultrastructural examination reveals increased matrix and mesangial hypercellularity. Occasional mesangial electron dense deposits are identified. The capillary basement membranes are focally thickened, and there is also focal fusion of the visceral epithelial cell foot processes. Most of the capillary lumina are occluded by endothelial swelling and inflammatory cells. There is focal subendothelial fibrin deposition, but no immune complex deposits are noted along the capillary loops.

Diagnosis and Comments

Kidney, needle biopsy- Henoch-Schönlein nephritis.

These features are most consistent with Henoch-Schonlein nephritis. Although the histologic features are essentially identical to IgA nephropathy, the presence of segmental necrotizing lesions and crescents is more typical of Henoch-Schonlein nephritis. Furthermore, this correlates much better with the clinical history of systemic small-vessel vasculitis. Although the glomerular lesion is quite active, there is no significant tubulointerstitial scarring.

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

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