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Archive: December 2017

Embryonal Hyperplasia of Bowman’s Capsule Epithelium

H&E and PAS-stained sections from the kidney of an 8-year-old male with advanced nephrosclerosis of unknown etiology. An exuberant proliferation of epithelial cells with an embryonal or immature appearance, arranged in a tubular and nodular pattern, is seen surrounding globally sclerotic glomeruli.  This unusual finding termed “embryonal hyperplasia/metaplasia of Bowman’s capsule epithelium” has been described in patients with end-stage renal disease on long-term dialysis. More recently, this finding has also been associated with WT1 mutations in patients with Denys-Drash syndrome and isolated diffuse mesangial sclerosis. The clinical significance of this finding is yet to be determined. References: 1. Hughson MD,...

Arkanines: Rashad

Meet Rashad! This boy is the sweetest, even when his mom makes him pose by the Christmas tree in his new sweater. He is also very patient with his puppy sister, who loves to torture him. He belongs to Chassity, who works on our marketing team. Happy Holidays, from all of our Arkanines friends!

Anti-Brush Border Antibody Disease

Anti-LRP2 nephropathy is a form of kidney disease primarily affecting the elderly in which progressive renal tubular injury is seen in association with circulating autoantibodies to the tubular brush border protein LRP2 (aka megalin). Histopathologically, it is characterized by IgG immune complexes in the tubular basement membrane. Similar tubular basement membrane deposits can be seen in other diseases such as lupus nephritis and IgG4-related disease. However, TBM staining for LRP2 is unique to cases with anti-LPR2 nephropathy. Normally, LRP2 is restricted to the apical membrane of the proximal tubules. LRP2 staining along the tubular basement membranes is abnormal indicates the...

Crescentic Glomerulonephritis with IgA Deposits

This biopsy was taken from a 58-year-old male with no significant past medical history, who presents with gross hematuria, serum creatinine of 2.5 mg/dl and a urine protein/creatinine ratio of 1.4 g/g. The biopsy shows segmental rupture of the capillary loops associated with fibrinoid necrosis of the glomerular tuft and cellular crescent formation (Fig 1 – Jones stain). Of note, no mesangial or endocapillary proliferation is present. Immunofluorescence (Fig 2) shows mesangial granular staining for IgA (3+), C3 (1+), kappa (2+) and lambda (3+). Electron microscopy (not shown) shows scattered mesangial electron-dense deposits. The differential diagnosis in patients with necrotizing and...

Anti-Brush Border Antibody Disease IF

These photomicrographs show the classic immunofluorescence staining pattern for anti-LRP2 nephropathy, a disease that leads to severe renal tubular injury and is associated with circulating autoantibodies to the tubular brush border protein LRP2/megalin. The images show granular IgG staining along proximal tubular basement membrane, Bowman’s capsule, and segmental glomerular basement membrane staining. The presence of IgG-containing TBM immune deposits, particularly in elderly patients, should alert the clinician and pathologist to the possibility of this disorder. Similar tubular deposits can be seen in the setting of lupus nephritis and IgG4-related disease. Tubular deposits in the setting of lupus generally correlate with...

IgG4-Related Tubulointerstitial Nephritis

IgG4-related disease is a systemic inflammatory and sclerosing disorder which may affect a wide range of different organs including the pancreas, salivary glands, lacrimal glands, lungs, blood vessels, lymph nodes, thyroid and kidneys among others. Patients may have multisystemic disease at the time of presentation, or different organs may progressively become involved over time. While the renal involvement may have different histopathologic patterns of injury, by far the most common is in the form of acute or chronic tubulointerstitial nephritis (IgG4-related tubulointerstitial nephritis). The renal biopsy shown (Fig 1-4) is from a 35-year-old male with a history of lymphadenopathy and...

Cholesterol Microemboli

Cholesterol emboli involving the kidney may manifest clinically as acute kidney injury, hematuria, proteinuria (both non-nephrotic and nephrotic range), and even new-onset hypertension. This biopsy illustrates a rare example of glomerular involvement (Fig. 1). Most emboli are identified “upstream” within interlobular and/or arcuate arteries (Fig. 2). Prior to this biopsy, the patient had recently undergone an arterial catheterization procedure. Lusco MA, et al. AJKD Atlas of Renal Pathology: Cholesterol Emboli. Am J Kidney Dis. 2016 Apr; 67(4):e23-4. PMID: 27012950.

Malignant Hypertension

This renal biopsy shown here is from a 25-year-old male who presented with acute kidney injury in the setting of hypertensive emergency (260/140). He has no significant past medical history. Serum creatinine is 3.1 and proteinuria is 3.2 g. Hemoglobin is low but platelet count is normal. This photomicrograph is representative of the changes in the biopsy including vascular microangiopathic changes (arrows) such as intimal edema with associated fibrin thrombi and schistocytes. Glomeruli were ischemic in appearance but did not show involvement by fibrin thrombi. The findings are consistent with those classically described secondary to accelerated/malignant hypertension. However, given the...