CRP-06

CRP-06

Clinical History

The patient is a 57 year old female.

Nephrotic syndrome of unknown etiology. Negative ANA, negative ANCA. Urinary protein 4 g/24 hr. Creatinine 0.9.

Gross Description

Received in transport media are two cores; each measures 11 mm in length and 2 mm in diameter. Two 1-mm pieces are taken for EM, and the remainder is bisected and equally divided for light and immunofluorescence microscopy.

Pathology

Case CRP-006 Silver

Microscopic Description, Immunofluorescence, and Electron Microscopy.

Microscopic Description

Light Microscopy

The specimen consists of two fragments of renal cortex and medulla. Each fragment contains cortex and medulla, although cortex is present in one fragment only in the first level. There are 23 glomeruli in the three levels examined. Five of these are completely obsolete, and four others show segmental sclerosis with intracapillary foam cells, hypertrophied visceral epithelial cells, and focal adhesions to Bowman's capsule. The remaining glomeruli generally showed diffuse mild mesangial expansion and mild mesangial cell proliferation. The capillary basement membranes are unremarkable with the silver and PASH stains. The trichrome stain shows mild patchy interstitial fibrosis, but there is minimal focal tubular atrophy. There are no inflammatory infiltrates. Arterioles and small arteries show only mild intimal thickening.

Immunofluorescence

There are seven glomeruli in the sections. There is 2+ focal and segmental mesangial staining for IgM and C3. This appears to represent segmentally collapsed areas primarily, although one glomerulus shows diffuse staining. There is no glomerular staining for IgG, IgA, Clq or light chains. There is no staining of the tubular basement membranes or vessels. Tubular epithelium contains protein droplets that stain for albumin and light chains.

Electron Microscopy

Two thick sections containing a total of three glomeruli are available. These are similar to those described above and show diffuse mild mesangial expansion and very mild hypercellularity. None of these glomeruli show segmental collapse. Ultrastructural examination confirms mild increase in mesangial matrix, and the capillary basement membranes are generally mildly thickened. There is diffuse fusion of the epithelial cell foot processes. No electron dense deposits are identified in the glomeruli.

Diagnosis and Comments

Kidney, needle biopsy - Focal segmental glomerulosclerosis.

These findings are most consistent with primary focal segmental glomerulosclerosis. Secondary focal segmental glomerulosclerosis due to vascular disease appears unlikely, since the degree of vascular disease in this biopsy is relatively mild. Furthermore, there is very little tubulointerstitial scarring. There is no evidence for an immune complex-mediated glomerulopathy. There is no evidence for a systemic disease process such as amyloidosis.

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