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Currently filtering by tag: Congo red

ALECT2 Amyloidosis

The patient is a 75-year-old Hispanic male who presents with progressively worsening kidney function and a creatinine of 1.6 mg/dl (baseline 1.0 mg/dl). His physician called for a biopsy due to a slowly "creeping" creatinine over the last 8 months. Images 1 & 2 show "apple-green birefringence" on a Congo red stain under polarized light within the interstitium. Image 3 shows mild interstitial fibrosis. Image 4 shows a normal glomerulus on PAS stain and Image 5 shows positive immunohistochemical staining with Lect2. Leukocyte cell-derived chemotaxin 2 (ALECT2) amyloidosis preferentially affects Hispanics (particularly Mexicans) as well as Punjabis, First Nations people...

Diagnose This (April 1, 2019)

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

Step By Step

The biopsy is from a 65 year-old female who presented with acute renal failure and elevated creatinine up to 1.9 mg/dl.  She has non-ischemic cardiomyopathy and protein electrophoresis is positive for lambda light chains.  Serologies for ANA and rheumatoid factor are within normal limits.  A biopsy was performed to rule out paraprotein associated disease and there was a specific concern for amyloidosis, due to cardiac changes. The biopsy consisted of a good sample, contained multiple cores of tissue and more than 20 glomeruli.   The glomeruli were very unremarkable by light microscopy – loops were open, with regular contours, and no...

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...

Vascular-Limited AL Amyloidosis

A renal biopsy was performed on this 78 year old male with history of diabetes mellitus, hypertension and monoclonal gammopathy of undetermined significance (IgG kappa). The serum creatinine at presentation was 3.2 mg/dl and UPCR was 1.8 g/g.  The glomeruli diffusely show nodular mesangial expansion with segmental sclerosis and negative Congo red staining, consistent with diabetic glomerulosclerosis. On the other hand, the arteries and arterioles diffusely show deposition of a PAS pale, weakly argyrophilic, Congo red positive amorphous material which shows apple green birefringence upon polarization, consistent with amyloid deposits (Fig 1 and 2, Congo red). Similar deposits are not...

Light Chain Cast Nephropathy with Congo Red Staining

This biopsy was taken from a 60-year-old African American female with a history of diabetes mellitus and hypertension, who presented with acute kidney injury and a serum creatinine of 5.8 mg/dl. Workup revealed an IgA kappa monoclonal band by serum protein electrophoresis. The biopsy shows numerous PAS-pale, focally fractured tubular casts with associated cellular reaction (Fig 1). These casts frequently stained positive for Congo red (Fig 2), and focally showed apple-green birefringence upon polarization. Otherwise, Congo red stain was diffusely negative within the glomeruli, interstitium, vessels, and cytoplasm of tubular epithelium. Immunofluorescence showed kappa light chain restriction of the casts...

Pushing Glass (April 6, 2018)

A 75-year-old Hispanic male presents with a creatinine of 3. His creatinine has slowly been creeping up over the last year from 1.8 to the current level. No hematuria or proteinuria is reported. Serologies for ANA, dsDNA, rheumatoid factor, hepatitis B, hepatitis C, and ASO are negative. Complement levels are normal. SPEP and UPEP are within normal limits. What is the best diagnosis? A. Arterionephrosclerosis B. Amyloidosis, AL-Type C. Amyloidosis, AA-Type D. Amyloidosis, ALect2-Type   The best answer is D (Amyloidosis, ALect2-Type). From low power, the glomeruli have an ischemic appearance and the arteries have severe arteriosclerosis. However, the Congo...

Congo Red Stain Tutorial

Positive Congo red staining in tissue with apple-green birefringence under polarized light is diagnostic of the presence of amyloid fibrils. Image A shows a glomerulus with Congo red positive mesangial staining while image B shows a renal biopsy with diabetic nephropathy that is negative for Congo red. Accurate interpretation of this stain hinges upon proper optimization so that there is elimination of nonspecific background staining.

Fibrinogen Aα-chain Amyloidosis

A 65-year-old male, with no significant past medical history, presents with proteinuria and worsening renal function. The serum creatinine is 2.4 mg/dl and the UPCR is 2.5 g/g.  Serum and urine protein electrophoresis with immunofixation shows the absence of monoclonal immunoglobulin.  Free serum light chain ratio is within normal limits.  Remaining of serologies are also negative/normal.  A renal biopsy was performed and representative images are shown (Fig 1-5).  The glomeruli are markedly enlarged and show massive deposition of PAS-pale (Fig 1), weakly argyrophilic (Fig 2), Congo red positive (Fig 3) amorphous material which shows apple green birefringence upon polarization (Fig...

Apolipoprotein A-IV Amyloidosis

This renal biopsy from a 71-year-old female, who presented with progressively worsening renal failure, shows unremarkable glomeruli by light microscopy (Fig 1), with minimal associated tubulointerstitial chronic injury. Of note, multifocal PAS-pale, weakly argyrophilic, Congo red positive (Fig 2) deposits with apple green birefringence (Fig 3), consistent with amyloid deposits, are present exclusively within the interstitium of the renal medulla. No amyloid deposition is present within the renal cortex or involving vascular structures.  The deposits show no light chain restriction by routine or paraffin immunofluorescence (not shown), making the possibility of light chain-type amyloidosis unlikely.  Furthermore, an immunoperoxidase stain for...