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Archive: August 2018

Twitter Post (August 30, 2018)

ANSWER: B Type II (mixed) cryoglobulinemia is characterized by immune-complexes containing a monoclonal Ig (usually IgM) that have an RF activity and polyclonal Ig (usually IgG). It’s most commonly caused by HCV, with some cases caused by lymphoproliferative or autoimmune disorders. References: Zaidan M, et al. Spectrum and prognosis of noninfectious renal mixed cryoglobulinemic GN. J Am Soc Nephrol 2016; 27:1-12. Fabrizi F, et al. Hepatitis C virus infection, mixed cryoglobulinemia, and kidney disease. Am J Kidney Dis 2013; 61(4): 623-637.  

Differential Diagnosis of Kidney Injury in CLL/SLL Patients

There are many causes of decreased kidney function in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and a renal biopsy may provide a definitive diagnosis. Prerenal etiologies include poor oral intake, sepsis, and heart failure.  Intrarenal causes include diseases of the glomeruli (e.g. minimal change disease, MPGN pattern glomerulopathy, membranous glomerulopathy), tubules (e.g. toxic or ischemic tubular injury/necrosis, light chain cast nephropathy), interstitium (e.g. acute interstitial nephritis caused by infection or drugs), and vasculature (e.g. TMA).  The biopsy shown in this image illustrates infiltration of the kidney parenchyma by the lymphoid neoplasm (characteristic immunophenotypic studies not shown).  Postrenal causes...

Proliferative Glomerulonephritis with Monoclonal IgG Deposits

This biopsy was performed on a 58-year-old female who presented with mild proteinuria. The glomeruli show diffuse and global endocapillary hypercellularity with segmental double contour formation of the capillary loops on the silver stain (Fig 1). Immunofluorescence shows mesangial and segmental capillary wall deposits positive for IgG (3+, Fig 2), C3 (3+, not shown), C1q (1+, not shown) and lambda light chain (3+, Figure 4). Staining for kappa light chain is negative in glomeruli (Fig 3). Further immunofluorescence staining for IgG subclasses proves the deposits to be IgG3 restricted. Electron microscopy shows mesangial and segmental subendothelial immune-complex type deposits. The...

Diagnose This (August 27, 2018)

What is this finding and what is the likely etiology?   ​   ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​   ​ ​   ​ ​    ...

Twitter Poll (August 22, 2018)

ANSWER: D Anti-GBM disease is a rare small vessel vasculitis that affects glomerular and pulmonary capillaries. The majority of patients develop widespread glomerular crescent formation, presenting with features of rapidly progressive GN, and 40-60% will have concurrent alveolar hemorrhage

Malpighi Glomerulus

How long have we known about glomeruli? Today’s teaching point is offered in honor of Marcello Malpighi (1628-1694), the Italian anatomist who is credited with having published the world’s first accurate description of glomerular structure (Bologna, Italy 1666). We learn from those who teach us! Bellomo G. A short history of 'glomerulus'. Clin Kidney J. 2013 Apr;6(2):250-1. PMID: 26019863 Fogazzi GB. The description of the renal glomeruli by Marcello Malpighi. Nephrol Dial Transplant. 1997 Oct;12(10):2191-2. PMID: 9351094. Image Credit (for oil painting, Malpighi): Wellcome Collection (https://wellcomecollection.org/) Podcast on Malpighi: https://www.arkanalabs.com/podcasts/malpighi/ 

Diagnose This (August 20, 2018)

What is your presumed diagnosis in the absence of immunofluorescence and electron microscopy?   ​   ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​   ​ ​   ​...

One little, two little, three little findings…

This biopsy came to us for evaluation of nephrotic syndrome. The patient is a Hispanic gentleman in his late 80s, with CKD stage IV and a history of arthritis, diabetes mellitus, coronary artery disease, and hypertension.  He had 4.9 g/g of proteinuria.  He had negative ANA, hepatitis B, and C serologies. C3 and C4 were within normal limits. Clinically, the differential diagnosis included membranous glomerulopathy and FSGS. The biopsy was a very good sample, consisting of long cores of renal tissue, mostly from cortex.  More than 20 glomeruli were present.  The glomeruli had clear features of diabetic nephropathy, as expected...

Interstitial Foam Cells

This 52-year-old female underwent a renal biopsy as part of the workup for nephrotic syndrome. The biopsy is diagnostic for PLA2R-positive membranous glomerulopathy with mild glomerular and tubulointerstitial chronic injury (not shown). Interestingly, the interstitium shows frequent clusters of interstitial foam cells (see image). While interstitial foam cells are commonly associated with Alport syndrome, they may actually be seen in a wide range of renal diseases resulting in heavy proteinuria, such as focal segmental glomerulosclerosis (FSGS), membranous glomerulopathy, IgA nephropathy and in diseases with a membranoproliferative pattern of glomerular injury. While it has been shown that interstitial foam cells contain...