CRP-07

CRP-07

Clinical History

The patient is a 26 year old black female.

Nephrotic syndrome. ANA 1:128, HIV negative, complements normal. Urinary protein 17 g/24 hr, creatinine 1.2.

Gross Description

Received in transport media are two cores measuring 14 and 15 mm in length and 2 mm in diameter. Three 1-mm pieces are taken for EM, and the remainder is bisected and divided equally for immunofluorescence and light microscopy.

Pathology

Case CRP-007 Silver

Microscopic Description, Immunofluorescence, and Electron Microscopy

Microscopic Description

Light Microscopy

The specimen consists of two fragments of renal cortex and medulla that contain 51 glomeruli in the three levels. None of these are obsolete. Twenty-two glomeruli demonstrate segmental or global capillary collapse with marked visceral cell hyperplasia and hypertrophy. Many of the visceral epithelial cells contain large protein droplets. The remaining glomeruli show mild mesangial expansion and hypercellularity. Silver stain does not demonstrate spike formation or double contours. Trichrome stain shows moderate diffuse interstitial fibrosis with corresponding tubular dropout, and the PASH stain demonstrates diffuse moderate atrophy as well. A number of the tubules are dilated with epithelial simplification, and they contain large casts. There are no inflammatory infiltrates in the cortex, although several collections of mononuclear inflammatory cells are present in the medulla. The arterioles and small arteries are unremarkable.

Immunofluorescence

There are thirty-one glomeruli in the sections. There is 2+ mesangial staining for IgG, Clq, C3 and kappa light chain. There is 1+ mesangial staining for IgA and lambda light chain, and there is trace mesangial staining for IgM. The staining is focal and global, although some staining is only segmental. There is no staining of the capillary loops. Tubular epithelium contains numerous protein droplets that stain for albumin. There is no staining of the tubular basement membranes or vessels.

Electron Microscopy

Three thick sections containing a total of five glomeruli are available. None of these show segmental or global collapse. Ultrastructural examination reveals focal thickening and wrinkling of the capillary basement membranes, collapse of the capillary lumina, and diffuse fusion of the epithelial cell foot processes. There is swelling and villous transformation of the visceral epithelial cells. A few small electron dense deposits are identified in paramesangial regions, but none are noted along the capillary basement membranes.

Diagnosis and Comments

Kidney, needle biopsy- Focal segmental glomerulosclerosis, collapsing variant.

The light and electron microscopic features are typical of the collapsing variant of focal segmental glomerulosclerosis, which occurs most commonly in young black patients. This form of focal segmental glomerulosclerosis generally carries a much poorer prognosis than the classic variety. The immunofluorescence microscopic findings are unusual, but I think this simply represents nonspecific trapping of large proteins in the collapsed segments. The glomeruli available for electron microscopic were examined very carefully for immune complex deposits, but no convincing deposits were identified. There has already been significant irreversible tubulointerstitial injury.

A normal partial thromboplastin time is 28 to 37 seconds.

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