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KDIGO Connections: Membranous Glomerulopathy

Welcome to the first post in our new series KDIGO Connections, a series in which we are asking our nephrologist colleagues to educate us in real-world experiences treating kidney disease. In this series, Dr. David Bourne will be kicking it off with KDIGO guidelines for a kidney disease in visual abstract form. Our hope is that these posts will foster discussion regarding these diseases and how different providers approach them. Please share any points, pearls, questions, caveats, thoughts, or experience you have on the presented disease letting us all learn from your experience!  

A tale of two cores…

Core “A” and “B” were taken from the same patient during the same biopsy procedure. The red blood cells within the tubules in core “B” represent a biopsy artifact sometimes seen when multiple passes are made during the same biopsy procedure. One confirmatory clue is the presence of red blood cells surrounding the periphery of core “B” – these are not present in core “A” which was likely the first core taken during the biopsy.    

Where is the normal kidney tissue?

This kidney biopsy shows the histologic features characteristic of malakoplakia, which includes a dense, often obliterative, inflammatory infiltrate rich in histiocytes (Fig. 1 and 2) with numerous small intracytoplasmic concretions known as Michaelis-Gutmann bodies (these are best identified using histochemical staining for calcium as in Fig. 3). Malakoplakia is thought to result from chronic bacterial infection of the urinary tract (the most common causative organism is E. coli). Many cases are associated with the formation of small plaques and/or mass lesions. The bladder is the most common site of involvement, but kidney involvement occurs in about 15% of cases. The...

Arteriole Transition

The image captures the transition of an arteriole as it loses its internal elastic lamina (black arrow).  Note that the smaller arteriole branch, while lacking this elastic layer, still retains smooth muscle cells (red arrow).  The elastic tissue adds structural integrity to arterial and larger arteriolar walls during pulsatile distension from higher intravascular pressure, and the retained muscular layer in small arterioles helps provide an important component of the pre-capillary sphincter mechanism, whereby regulation of blood flow to capillary beds occurs.    

IgA nephropathy with something extra…

The biopsy is from a 61-year-old man with a history of intermittent microscopic hematuria for many years who presents with recent 18-pound weight loss and nephrotic syndrome.  His creatinine is mildly elevated at 1.3 mg/dL.  He has 12.5 g of proteinuria and his serum albumin is 2.6 mg/dL.  The biopsy shows diffuse mild mesangial matrix expansion with no necrosis or proliferative lesions (Fig. 1).  Immunofluorescence microscopy shows extensive granular mesangial IgA deposits (3+) (Fig. 2), compatible with IgA nephropathy.  Interestingly, the Jones methenamine silver stain also shows argyrophilic spikes involving capillary loops, which are most suggestive of spicular amyloid deposits...

Infection-Associated Glomerulonephritis

This biopsy is taken from a 39-year-old woman who presents with abdominal pain, ascites, and lower extremity edema. Her serum creatinine is 3.9 mg/dL and her complete blood count shows leukocytosis (14,500). Initial serologic workup is negative. The biopsy shows a diffuse proliferative glomerulonephritis characterized by global endocapillary hypercellularity with prominent neutrophils, best visualized using methenamine silver staining (Fig. 1). No crescents, necrotizing lesions, or significant double contours are identified. By immunofluorescence, there is coarsely granular (3+) capillary wall and less prominent mesangial staining for IgG, C3, kappa, and lambda (Fig. 2). Electron microscopy shows global endocapillary proliferation and numerous...