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Archive: July 2018

Endocapillary Hypercellularity in Thrombotic Microangiopathy

This renal biopsy performed on a 14-year-old boy shows changes diagnostic of a thrombotic microangiopathy (TMA). These changes include frequent fibrin thrombi within the arteriolar lumens and glomerular hilum, endothelial swelling, mesangiolysis and focal glomerular ischemic changes (Fig 1-3). Of note, the glomeruli frequently show marked global endocapillary hypercellularity, mostly composed of swollen endothelial cells and occasional circulating inflammatory cells (Fig 4). Immunofluorescence and electron microscopy show absence of immune complex deposition (not shown). This case illustrates that a subset of cases of TMA may show endocapillary hypercellularity and is important to avoid misdiagnosing such cases as a proliferative glomerulonephritis....

Nephronophthisis by Light Microscopy

Nephronophthisis is an autosomal recessive tubulointerstitial nephropathy that is a leading genetic etiology of end-stage renal disease in children and young adults. Approximately 60% of patients with a known genetic etiology of nephronophthisis are due to homozygous deletion of the NPHP1 gene. The histopathologic lesions associated with nephronophthisis are shown in these photomicrographs. (A) A tubular floret profile with complicated tubular branching in at least 4 directions (PAS; original magnification ×400). (B) Macula densa-like lesions (arrows) are tubular profiles in which there is a transition to a grouping of cells with crowded, hyperchromatic nuclei and a high nuclear: cytoplasmic ratio...

Anti-VEGF Effect

This biopsy was taken from an older adult man with acute kidney injury and non-nephrotic range proteinuria.  His medical history included metastatic colonic adenocarcinoma, for which he was taking bevacizumab, an anti-vascular endothelial growth factor (anti-VEGF) inhibitor.  The sampled glomeruli show changes of thrombotic microangiopathy (TMA), including double contour formation of glomerular capillaries (Fig. 1) and intracapillary red blood cell fragmentation (Fig. 2).  TMA is one of the most common adverse effects in the kidney of bevacizumab therapy, and it has been reported as early as one week after starting the drug.  Other pathologies reported in the setting of anti-VEGF...

Smoking-Related Glomerulopathy

A renal biopsy was performed on this 52-year-old male with a history of hypertension and heavy tobacco use, who is being worked up for nephrotic range proteinuria and increased creatinine. The glomeruli (Fig 1 and 2) show nodular mesangial matrix expansion without definitive proliferation, necrosis or crescents. Focal areas of segmental glomerulosclerosis are present. There is no evidence of immune complex or monoclonal immunoglobulin deposition by immunofluorescence or electron microscopy. Of note, electron microscopy does show global thickening of glomerular basement membranes (not shown). While non-specific, the most common cause of nodular glomerulosclerosis in the United States is diabetes mellitus/glucose...

Diagnose This (July 23, 2018)

What is your diagnosis?   ​   ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​   ​ ​   ​ ​     ​   ​   ​ ​...

A Board Party!

We are so excited to celebrate with Dr. Dvanajscak and Dr. Caza today.  They have both passed their pathology boards!  Cupcakes all around! 

Twitter Poll (July 18, 2018)

ANSWER: D In a case series by Boils et al. which included 49 patients with GN due to IE, 28% of them had positive ANCA antibodies. Of note, in this study it was described that only 29 out of 49 patients had serology drawn for ANCA, 21 were negative (72%) and 8 (28%) were positive. Reference: Boils CL, et al. Update on endocarditis-associated glomerulonephritis. Kidney Int 2015; 87(6): 1241-1249.

Nephronophthisis by ISH

Nephronophthisis is an autosomal recessive tubulointerstitial nephropathy that is a leading genetic etiology of end stage renal disease in children and young adults. Approximately 60% of patients with a known genetic etiology of nephronophthisis are due to homozygous deletion of the NPHP1 gene. Fluorescence In-Situ Hybridization is both sensitive and specific for the detection of NPHP1 deletion in renal biopsies suspected to represent nephronophthisis. (A) Cases without NPHP1 deletion show nuclear profiles (DAPI blue) with two probe signals for both the control centromeric probe CEP2 (FITC green) and NPHP1 (CY3 orange). An arrow indicates a nuclear profile with two signals of...

HIVAN

This biopsy is taken from a patient with HIV/AIDS who presented with an elevated serum creatinine and nephrotic range proteinuria.  Key morphologic features associated with HIV-related kidney disease include collapsing glomerular lesions, microcystic tubular dilatation and variable tubular epithelial injury, and interstitial inflammation and edema (see Fig 1-3).  In addition to these findings, other kidney diseases seen in patients with HIV include the following:  HIV immune complex kidney disease (HIVICK), various other immune complex diseases (e.g. hepatitis C virus, membranous glomerulopathy), HIV-associated lupus-like glomerulonephritis, thrombotic microangiopathy, and various renal tumors (e.g. Kaposi sarcoma, lymphoma).