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Currently filtering by tag: Chronic kidney disease

Twitter Poll (September 26, 2019)

ANSWER: C APOL1-risk alleles have been reported only on African-derived chromosomes, including individuals from West Africa and recently admixed individuals from the United States or the Caribbean. Approximately 13% of the US African American population carries the APOL1 high-risk genotype. Recent data suggest that this risk is strongly associated with two common variants (G1 and G2) in the last exon of APOL1 that confer resistance to Trypanosoma brucei infections. The highest G1 and G2 allelic frequencies were described in Western, sub-Saharan Africa, with frequencies >40% for G1 in Ghana and Nigeria, and 24% for G2 in Nigeria. REFERENCES: Parsa A, Kao WHL, Xie D,...

Twitter Poll (May 22, 2019)

ANSWER: C By the Oxford Classification of IgA nephropathy, the findings present are classified as "M1 E1 S1 T1 C0" (where M=Mesangial hypercellularity; E=Endocapillary proliferation; S=Segmental sclerosis; T=Tubular atrophy & interstitial fibrosis; C=Cellular/fibrocellular crescents). REFERENCE: Trimarchi H, et al. Oxford Classification of IgA Nephropathy 2016: an update from the IgA Nephropathy Classification Working Group. Kidney Int 2017; 91(5):1014-21.    

Crescentic IgA nephropathy

The patient is a 17-year-old white female who presents with 2.85 grams/24 hr proteinuria, microscopic hematuria, and a creatinine of 3.2 mg/dl. She was in her normal state of health and was incidentally found to have abnormal lab values and urinalysis at a routine sport's physical. She reports that she had noticed a little more fatigue the last few months, but had blamed this on being busy at her job after school. Figure 1 shows focal fibrinoid necrosis. Figure 2 shows moderate tubular atrophy and interstitial fibrosis. Figures 3 & 4 show a segmental cellular crescent. Figure 5 shows several...

Twitter Poll (January 16, 2019)

ANSWER: B The target of the circulating ABBA autoantibodies is LDL receptor-related protein 2 (LRP2) also known as “Megalin”. ABBA is a rare autoimmune disease associated with acute kidney injury and tubulointerstitial damage.  Histologically, IgG–positive immune deposits are found in tubular basement membranes by immunofluorescence (IF).  When indirect IF is done using patient’s serum and normal kidney controls, there is reaction of the autoantibodies with the proximal tubular brush borders. REFERENCE: Larsen CP, et al. LDL-Receptor Related Protein 2 (Megalin) as a Target Antigen in Human Kidney Anti-Brush Border Antibody Disease. J Am Soc Nephrol, 2018; 29:644-653    

Disease Week: Fibrillary Glomerulopathy

Fibrillary GN is a disease undergoing rapid change. In just ten years several clinical disease state associations have been defined, a new treatment paradigm has emerged, new diagnostic tests on renal biopsy have been discovered, and the beginnings of the molecular pathogenesis of the disease have been found. In the coming years, I hope continued research will help us answer a few important questions. First, no controlled, large scale, collaborative trials exist that prove treatment superiority in this disease and are sorely needed. Next, I hope that the discovery of DNAJB9 as a biomarker of this disease ignites a flurry...

Twitter Poll (January 9, 2019)

ANSWER: C DNAJB9 immunohistochemical (IHC) stain is a quick and inexpensive tool used to confirm the diagnosis of Fibrillary GN. DNAJB9 IHC has a sensitivity of 98% and >99% specificity.   In 2017, Dr. Nasr et al. discovered a novel proteomic biomarker for Fibrillary GN called DnaJ homolog subfamily B member 9 (DNAJB9), which is a member of the chaperone gene family. DNAJB9 immunohistochemical (IHC) stain is a quick and inexpensive tool used to confirm the diagnosis of Fibrillary GN. DNAJB9 IHC has a sensitivity of 98% and >99% specificity.   Reference: Nasr S, et al. DNAJB9 is a specific...

Art of Medicine: Uromodulin

Welcome to our first post in the Art of Medicine series! In the hustle and bustle of busy clinics, labs, and hospitals we are often focused on the practical aspects of the practice of medicine. Dr. Tiffany Caza is the content creator for this series as well as being a renal pathologist and artist. Her art focuses on her interpretations of the histologic, cellular, and sub-cellular milieu where a dazzling variety of chemical and structural forces inherent to all life exist. In this series, she will be sharing her art (and occasionally others) and providing correlates to the science represented...

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...

DNAJB9 helps uncover dual pathology…

This case illustrates the utility of immunohistochemical staining for DNAJB9, a recently described biomarker for fibrillary glomerulopathy (see reference).  The renal biopsy is taken from a 68-year-old man with a history of cirrhosis (cause unknown) who presents with mild microscopic hematuria, non-nephrotic range proteinuria, and chronic renal failure.  Glomeruli show diffuse mild mesangial matrix expansion.  Immunofluorescence shows granular mesangial IgA (2+) and smudgy mesangial and capillary wall IgG (2+) staining.  Electron microscopy (not shown) shows both immune complex-type and fibrillary deposits involving glomerular capillary basement membranes and mesangium.  Immunohistochemical staining for DNAJB9 shows mesangial staining.  Although IgA immunofluorescence staining may...