INTERPRETATION OF RENAL BIOPSYPresented by- Dr.Biswajeeta Saha,

Moderator- Dr.A.K.Patra,

Dept. of Pathology, KIMS, BBSR.

Introduction

The kidney is a mysterious organ that makes urine

Has role in-

Excreting wastes

Regulating body fluids

Balancing soluble ions

Anatomy Kidneys-bean shape organs within peritoneum Each organ weights 125 to 170 gm in males and 115 to 150 gr in

females The renal artery divides into anterior and posterior arteries which

in turn give off segmental arteries

The main renal artery gives off- Interlobar Arcuate Interlobular arteries On the cut surface-cortex and medulla medulla is divided to 18 pyramids Each pyramid base is located at the corticomedullary junction

Nephrons-• Functional and basic unit • Composed of glomeruli,bowman’s capsule, PCT, DCT & henle’s loop.• Glomeruli-cortex• Henle’s loop-medulla• Nephrons-1 million

Glomeruli-• Malphigi first described glomerulus• Glomerulus-glomerular tuft + bowman’s capsule• Glomerulus-vascular tuft lined by endothelium,supported by mesangium• 200 μm.

Proximal tubule-• 14mm long.• Cells are cuboid/short columnar,eosinophilic cytoplasm,granular,round

nucleus in centre.with brush border• Reabsorption of majority glomerular ultrafiltrate.

Henle’s loop-

• Between proximal and distal tubules

• U-shaped unit

• Cells are flat, attenuated cytoplasm, no brush border

Distal tubule-

• Connects to ascending henle’s loop

• No brush border

Collecting duct-

• Begins near end of DCT in cortex

• Potassium secretion

HISTOLOGY GLOMERULUS

TUBULES

HISTORY OF RENAL BIOPSY Iverson and Brun (1951)- first renal biopsy description

INDICATIONS OF RENAL BIOPSY

Nephrotic syndrome:› Adult NS› Children with atypical

features Acute renal failure:

› Undiagnosed› Non resolving clinical ATN

>3-4 weeks Systemic diseases with renal

dysfunction Sub-nephrotic proteinuria

› >2g/d in DM, early MGN, FSGS, IgAN

› <2g/d needs clinicians discretion

Hematuria› Isolated› Associated with proteinuria

and abnormal urine sediment

Post transplant

CKD- generally contraindicated In moderate dysfunction-

potential reversibility and basic disease

Diabetes Mellitus Microscopic hematuria Absence of retinopathy and

neuropathy Onset of proteinuria <5years

from diagnosis Acute worsening of renal

function Systemic features

CONTRAINDICATIONS

Biopsy technique Renal biopsies taken by True-cut or biopsy gun under local anesthesia performed in prone position for native kidneys and in supine position for

transplanted kidneys It is better to use 16 or 14 guage needle optimum location for biopsy is juxtamedullary Other renal biopsy techniques include transjugular retrograde approach

by catheter, laparascopic techniques, and open laparatomic biopsy.

Procedure- Informed consent Patient in prone position with wedge or pillow below the abdomen Light sedation Local anesthesia with 1-2% lignocaine from the skin down to the capsule Stab incision can be given to ease biopsy gun entry Advance the biopsy gun, when the capsule is reached, instruct patient to

take a deep breath and fire the gun 2-3 cores can be taken from the lower pole of the left kidney Press on wound for 2-5 minutes

Post procedure- Bed rest is instructed for 18-24 hours BP and pulse are monitored in the following way-

Every 15 mins for 1 hour Every 30 mins for 1 hour Every hour for 4 hours 4 hourly for next remaining 24 hours

Save aliquots of each voided urine sample in clear specimen jars Hct monitored 6-8 hours and 18-24 hours after biopsy

Complications- Hematoma Hematuria AV fistula

Fixatives- For light microscopy, neutral buffered formaldehyde is used suitable for immunohistochemical study and also molecular

procedures For electron microscopy, 2-3% glutaraldehyde fluid is suitable. Immunofluorescence samples do not need any fixative and

should be delivered and frozen in Michel`s media for frozen sections

Specimen division- >8mm - LM/IF/EM 4-8mm - EM/IF <4mm - EM

Adequacy of the sample:› two biopsy cylinders with a minimal length of 1 cm and a

diameter of at least 1.2 mm.› 10–15 glomeruli are optimal; very often 6–10 glomeruli are

sufficient› some cases even one glomerulus is enough

Sectioning and staining-

› After histologic processing and paraffin embedding, the

tissues are sectioned by microtome

› sections are prepared as thin as 3 μm or less for light

microscopy. Thicker sections is needed in congo red and

Immunohistochemistry staining.

› Most helpful stains are-HE, PAS, Massons trichrome, JMS and

congo red.

PAS TRICHROME

SILVER

Basement membrane

red deep blue black

Mesangial matrix

red deep blue black

Interstitial collagen

------ pale blue -------

Cell cytoplasm ------- rust/orange granular

------

Immune complex deposit

-/+ bright red orange,homogenous

-----

Fibrin weakly + Bright red orange,fibrillar

----

amyloid -------- Light blue orange

----

Biopsy tissue examination

Light microscopy(L

M)

IHC-IF

Electron Microscopy

(EM)

RENAL BIOPSY EVALUATION

Glomeruli

Tubules

Interstitium

Vessels

Tissue examination

A. Injury Localization: Glomerular/Vascular/TubulointerstitialB. Category of Injury: Active Versus Fibrosing1. Active lesions a. Proliferation b. Necrosis c. Crescents d. Edema e. Active inflammation (eg, glomerulitis, tubulitis, vasculitis)2. Fibrosing a. Glomerulosclerosis b. Fibrous crescents c. Tubular atrophy d. Interstitial fibrosis e. Vascular sclerosisC. Types of Lesions 1. Determination of the nature and pathogenesis of lesions:

examination by IF, EM and LM

Systemic evaluation of renal biopsy

GLOMERULI

Focal/diffuseGlobal/segmentalNumber & sizeCellularityDepositsMesangiumFibrinoid necrosis & crescents

TUBULOINTERSTITIUM

Tubular atrophy/dilatationNecrosisInterstitial inflammationInterstiial fibrosisEMAdditional features

VESSELS

Wall thickeningHyalinosisFibrinoid necrosisEndothelitis

GLOMERULAR PATHOLOGY

Standard terminologies Focal-Involving <50% of glomeruli Diffuse-Involving 50% or more of glomeruli Segmental-Involving part of a glomerular tuft Global-Involving all of a glomerular tuft Mesangial hypercellularity-4 or more nuclei in a peripheral mesangial

segment Endocapillary hypercellularity-Increased cellularity internal to the GBM

composed of leukocytes, endothelial cells and/or mesangial cells Extracapillary hypercellularity-Increased cellularity in Bowman’s space,

i.e. > one layer of parietal or visceral epithelial cells, or monocytes/macrophages

Crescent-Extracapillary hypercellularity other than the epithelial hyperplasia of collapsing variant of FSGS

Fibrinoid necrosis-Lytic destruction of cells and matrix with deposition of acidophilic fibrin-rich material

Sclerosis-Increased collagenous extracellular matrix that is expanding the mesangium, obliterating capillary lumens or forming adhesions to Bowman’s capsule

Hyaline-Glassy acidophilic extracellular material Membranoproliferative-Combined capillary wall thickening and

endocapillary hypercellularity Lobular -Consolidated expansion of segments that are demarcated by

intervening urinary space Mesangiolysis-lysis of mesangial matrix

Patterns of glomerular injury by LM No abnormality by light microscopy:1. No glomerular disease2. Glomerular disease with no light microscopic changes (e.g.

minimal change glomerulopathy, thin basement membrane nephropathy)

3. Mild or early glomerular disease (e.g. Class I lupus nephritis, IgA nephropathy, C1q nephropathy, Alport syndrome, etc.)

Thick capillary walls without hypercellularity or mesangial expansion:

1. Membranous glomerulopathy (primary or secondary) (>Stage I)2. Thrombotic microangiopathy with expanded subendothelial zone3. Preeclampsia/eclampsia with endothelial swelling3. Fibrillary glomerulonephritis with predominance of capillary wall

deposits

Thick walls with mesangial expansion but little or no hypercellularity:

1. Diabetic glomerulosclerosis with diffuse rather than nodular sclerosis

2. Secondary membranous glomerulopathy with mesangial immune deposits

3. Amyloidosis4. Monoclonal immunoglobulin deposition disease5. Fibrillary glomerulonephritis6. Dense deposit disease (type II membranoproliferative

glomerulonephritis)

Focal segmental glomerular sclerosis without hypercellularity:

1. Focal segmental glomerulosclerosis (primary or secondary)2. Chronic sclerotic phase of a focal glomerulonephritis3. Hereditary nephritis (Alport syndrome)

Mesangial or endocapillary hypercellularity:1. Focal or diffuse mesangioproliferative glomerulonephritis*2. Focal or diffuse (endocapillary) proliferative glomerulonephritis*3. Acute (“exudative”) diffuse proliferative postinfectious

glomerulonephritis4. Membranoproliferative glomerulonephritis (type I, II or III)

Extracapillary hypercellularity:1. ANCA crescentic glomerulonephritis (paucity of immunoglobulin by IFM)2. Immune complex crescentic glomerulonephritis ((granular immunoglobulin

by IFM)3. Anti-GBM crescentic glomerulonephritis (linear immunoglobulin by IFM)4. Collapsing variant of focal segmental glomerulosclerosis (including HIV

nephropathy)

Membranoproliferative, lobular or nodular pattern:1. Membranoproliferative glomerulonephritis (type I, II/DDD, or IIIB/IIIS)2. Diabetic glomerulosclerosis with nodular mesangial expansion (KW

nodules)3. Monoclonal immunoglobulin deposition disease with nodular sclerosis4. Idiopathic (smoking associated) nodular glomerulosclerosis5. Thrombotic microangiopathy6. Fibrillary glomerulonephritis7. Immunotactoid glomerulopathy

Advanced diffuse global glomerular sclerosis1. End stage glomerular disease2. End stage vascular disease3. End stage tubulointerstitial disease

Immunohistological evaluation of glomeruli

Directed at identification of pathogenic Ig and complement. Abs used routinely-IgG, IgA, IgM, Kappa & lambda light chains,

C3, C4, C1q, fibrinogen Glomerular/extraglomerular location,intensity & pattern of

staining Glomerular staining catagorized as-mesangial, capilary wall or

both Capillary staining –granular,linear,band like

Capillary granularmesangial both

Coarse granular granular

Fine granular Band like coarsely granular

Algorithm of interpretation of glomerular IF patterns

Linear cap wall Granular mesangial Granular cap wall Diffuse smudgy mes & cap wall

•Anti GBM disease(IgG, C3)

•Monoclonal Ig deposition disease(mostly kappa chain)

•Diabetic nephropathy(IgG,albumin)

•Dense deposit disease( ribbonlike,thick C3)

•Rarely fibrillary GN (IgG)

•IgA nephropathy

•WHO Class II lupus( full house)

•C1q nephropathy

•IgM is idiopathic nephrotic syndrome

•Other mesangioproliferative GN

•Finely granular (membranous GN with/without SLE)

•Coarsely granular (MPGN, WHO Class III, or IV lupus)

•Scattered ,coarse granules (poststreptococcal GN)

•Primary amyloidosis(usually λ)

•Fibrillary GN(IgG)

•Monoclonal Ig deposition disease

Electron micrscopic evaluation of glomeruli

Detailed evaluation of cellular & extracellular contents

Assesment of thickness,contour, & integrity of GBM &

mesangial matrix

Fibrillary GN & immunotactoid GP can be diagnosed only

on EM

Mesangial dense deposit(IgA)

Mesangial & subendothelial dense deposit(lupus IV)

SUBEPITHELIAL HUMP

Subendothelial dense deposit

TUBULAR PATHOLOGY

Pathologic diagnosis of tubular diseases

Diseases primarily affecting the tubules are considered under the

following headings

Acute tubular necrosis

Tubular casts

Chronic changes/tubular atrophy

Tubulitis

Tubular basement membrane changes

Acute tubular necrosis

Charaterised morphologically by destruction/severe injury of the renal tubular epithelium

2 major causes are-toxins & ischaemia

Evidence of ATN/injury are- Degeneration & necrosis of individual tubular epithelial cells Swelling of tubular epithelium(ballooning) Detachment of tubular epithelium from underlying BM Loss of PAS positive brush border of PCT Thinning of tubular epithelium Dilatation of tubular Lumina Interstitial edema Casts ( hyaline, pigmented, eosinophilic, cellular, granular debris) Tubular lumen contains sloughed epithelial cells, leukocytes,

cellular debris Rupture of tubular BM

OTHER ACUTE RENAL TUBULAR INJURIES

Hyaline droplet change-small to large eosinophilic PAS positive droplets

Vacuolar change- Hydropic change Foam cells Fatty change Hypokalemic nephropathy

Pigmented tubular epithelium

Intranuclear inclusions

Hydropic changeFatty change

Inclusions in lead intoxication

CMV inclusions

Tubulitis

Lymphocytes or other inflammatory cells on epithelial side of tubular BM infiltrating the tubular epithelium

Marker of active tubulointerstitial inflammation.

Tubular casts

Hyaline casts

WBC casts

Epithelial / granular casts

RBC casts

Large hyaline fractured casts

Myoglobin/hemoglobin casts

Tubular atrophy

Tubules are non functioning & it is no longer capable of regenerating and resuming function.

Accompanied by thickening of tubular BM Tubular BM are thickned & wrinkled

3 types of atrophic tubules-1. Classic atrophic tubules-thick wrinkled ocassional lamellated

tubular BM ,simplified cuboidal non descript epithelium

2. Endocrine tubules-narrow/no tubular lumen. clear epithelial cells, thin/absent BM

3. Thyroidized tubules-round tubules, simplified epithelium, uniform intratubular casts that mimic thyroid

4. Super tubules-enlarged, dilated. either hypertrophic/hyperplastic

Thickened BM

THYROIDIZATION

INTERSTITIAL DISEASES

Pathological diagnosis of interstitial diseases

No abnormality on LM- No interstitial disease Interstitial disease with no change Early disease

Interstitial expansion by edema ATN Renal vein thrombosis Nephrotic syndrome(MCD) AGN (acute lupus,APSGN) Thrombotic microangiopathy(HUS)

Interstitial expansion by eosinophilic material Collagen-fibrosis Sickle cell disease Radiation nephritis amyloid

Interstitial expansion by leukocytes Polymorphs(APSGN, drug induced, sepsis) Lymphoplasmacytic(chr nephritsi, vasculitis, rejection) Eosinophils (vasculitis, drug induced, lupus) Epitheloid(TB, sarcoidosis, drug induced, malakoplakia)

Expansion by foam cells Hereditary nephritis(alports syndrome) Abundant,prolonged proteinuria or Nephrotic

syndrome(membranous GN)

Interstitial hemorrhage Acute rejection Severe GN with rupture of bowmans capsule Malignant HTN Vasculitis

Interstitial expansion by neoplastic cells- Lymphoma Leukemia Primary renal ca Metastasis

Crystals & mineral deposits Nephrocalcinosis(ca carbonate) ARF(ca oxalate) Uric acid(gout) Cholesterol(glomerular disease with nephrotic syndrome)

edema Int nephritis polymorphs

granuloma DLBCL

VASCULAR LESIONS

Vasculitis Fibrinoid necrosis Thrombosis Pseudoaneurysm Infarct

Endothelitis

Deposition of material- Amyloid Hyaline arteriolosclerosis

Toxins Thrombotic microangiopathy Peripheral hyalin

Hypertension induced changes Medial hypertrophy Intimal thickening Replication of elastic lamina

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