Renal and Urinary Tract Pathology - Part 1

Question 1

Horseshoe Kidney - Location of Trapping

Answer 1

Inferior Mesenteric Artery

Question 2

Unilateral Renal Agenesis - Results (2)

Answer 2

1) Hyperfiltration + Hypertrophy of remaining kidney

2) Increased Risk of Renal Failure

Question 3

Bilateral Renal Agenesis - Pathophysiology + Results (2)

Answer 3

Path - Oligohydramnios (Low Amniotic Fluid from failure of fetus to urinate
Results
1) Not Compatible with LIfe
2) Potter Sequence

Question 4

Potter Sequence Mnemonic

Answer 4

1) P - Pulmonary Hypoplasia
2) O - Oligohydramnios (Cause)
3) T - Twisted Face
4) T - Twisted Skin
5) E - Extremity Defects
6) R - Renal Agenesis

Question 5

Dysplatic Kidney - Keys (3)

Answer 5

1) Non-inherited congenital malformation of the renal parenchyma
2) Characterized by cysts and abnormal tissue
3) Usually unilateral without enlargement (bilateral think polycystic kidney disease)

Question 6

Polycystic Kidney Disease (PKD) - Autosomal Recessive - 3 Keys

Answer 6

1) Bilateral + Associated with Congenital Hepatic Fibrosis
2) Failure can mimic agenesis and lead to symptoms similar to Potter
3) Presents in infancy

Question 7

Polycystic Kidney Disease (PKD) - Autosomal Dominant - 3 Keys

Answer 7

1) Bilateral + Associated with 3 “Cysts” - Kidney + Liver (Portal HTN) + Brain (Berry Aneurism)
2) Mutation in the APKD1 and APKD2 Gene
3) Presents in young adults

Question 8

Medullary Cystic Kidney Disease - Keys (2)

Answer 8

1) Autosomal dominant defect in the medullary collecting ducts
2) Results in shrunken kidney

Question 9

Types of Acute Renal Injury (3) + Alternative Name

Answer 9

1) Prerenal - Reduced Flow
2) Intrarenal - Renal Paranchyma
3) Postrenal - Obstruction

Azotemia (Accumulation of Nitrogenous Waste Products - BUN/Cr) + Oligouria (lack of urine)

Question 10

Major Types of Intrarenal Azotemia (3)

Answer 10

1) Acute Tubular Necrosis (ATN)
2) Acute Interstital Nephritis (AIN)
3) Renal Papillary Necrosis

Question 11

Pre-Renal Azotemia - Cause + Findings (5)

Answer 11

Cause - Reduced blood flow to the kidney

1) Oligouria
2) Decreased GFR
3) Elevated BUN/Cr (Azotemia)
4) BUN/Cr Ratio > 15 - Issue is no flow which triggers aldosterone release - Aldosterone release increases in H2O re-absorption and with in BUN - Cr is not reabsorbed so it is not impacted
5) Fractional Excretion of Na (FENa) > 1% indicated the tubule can still reabsorb Na

Question 12

Post-Renal Azotemia - Cause + Findings (5)

Answer 12

Obstruction - Causes back pressure reducing GFR

1) Oligouria
2) Decreased GFR
3) Elevated BUN/Cr (Azotemia)
4) Changes in BUN/Cr Ratio (Early > 15 //// Late < 15)
5) Changes in FENa (Early < 1% ////// Late > 2%)

Question 13

Post-Renal Azotemia - Early vs. Late Stage Findings - 2 Each

Answer 13

Early

1) BUN/Cr - Elevated ( > 15) - Increased tubular pressure “pushes” more BUN re-absorption
2) Functioning Tubule = FENa < 1%

Late

1) BUN/Cr - Reduced ( < 15) - Long term obstruction leads to tubular damage - which reduces the number of receptors for BUN re-absorption
2) Loss of Function = FENa > 2%

Question 14

Acute Tubular Necrosis - Cause + Findings (6)

Answer 14

Cause - Necrosis of Tubular Epithelial Cells

1) Muddy Brown Granular Casts
2) Oliguria
3) Azotemia
4) Hyperkalemia (decreased renal excretion) + metabolic acidosis (decreased organic acid secretion) - Anion Gap
5) BUN/Cr Ratio < 15 (Loss of BUN Re-absorption)
6) FENa > 2% + Inability to Concentrate Urine (Osm < 500)

Question 15

Acute Tubular Necrosis - Major Types (2)

Answer 15

1) Ischemia - Usually preceeded by pre-renal azotemia - Proximal Tubule + Thick Ascending Limb Hit Worst
2) Nephrotoxic - Toxic agents damage the proximal tubules

Question 16

Acute Tubular Necrosis - Nephrotoxic Causes (5)

Answer 16

1) Aminoglycosides (most common - Gentamicin)
2) Heavy Metal (Lead)
3) Myoglobuinuria (Crush Injury)
4) Ethylene Glycol (Oxalate Crystals)
5) Tumor Lysis Syndrome (Leukemia treatment massive cell death + increase in uric acid)

Question 17

Acute Interstitial Nephritis - Pathophysiology

Answer 17

Inflammation of Renal Connective Tissue - Hypersensitivity Reaction with Eosinophils

Question 18

Acute Interstitial Nephritis - Causes (3) + Findings (4)

Answer 18

Causes

1) NSAIDs
2) Penicllin
3) Diuretics

Findings

1) Eosinophils
2) Oliguria
3) Fever
4) Rash

Question 19

Renal Papillary Necrosis - Presentating S/Sx (2) + Causes (4)

Answer 19

S/Sx

1) Gross Hematuria
2) Flank Pain

Causes

1) Sickle Cell Trait
2) Diabetes
3) Chronic Analgesic Abuse
4) Severe Acute Pyelonephritis

Question 20

Nephrotic Syndrome - Basic Findings (5)

Answer 20

1) Proteinuria ( > 3.5g/day)
2) Hypoalbuminemia (Pitting Edema)
3) Hyperlipidemia (Fatty Casts in Liver)
4) Hypogammaglobulinemia - (Loss of Ig) - Increased risk for Infection
5) Hypercoaguable (Loss of Antithrombin III)

Question 21

Nephritic Syndrome - Basic Findings (5)

Answer 21

1) RBCs (Dysmorphic) and RBC Casts in Urine (Hematuria
2) Low Urine Volume (Oliguria)
3) Only Mild Proteinuria
4) Salt Retention + HTN
5) Hypercellular Glomerulus (Inflammation) with swelling into the Bowman’s Space on H&E

Question 22

Major Classes of Nephrotic Syndromes (6)

Answer 22

1) Minimal Change
2) Focal Segmental Glomerulosclerosis (FSGS)
3) Memranous Nephropathy
4) Membranoproliferative Glomerulonephritis
5) Diabetes Meleitus
6) Systemic Amyloidosis

Question 23

Minimal Change Disease - Cause + Key Findings (5)

Answer 23

Cause - Effacement of podocyte foot processes by cytokine storms (T-Cell Based)

Findings

1) Effacement on EM with normal H&E
2) Excellent Response to Steroids
3) Selective Alubmin proteinuria
4) No immune complex deposits (or IF)
5) Most common in children + Hodgkin’s

Question 24

Focal Segmental Glomerulosclerosis (FSGS) - Cause + Findings (4)

Answer 24

Cause - segmental sclerosis of glomerular filtration units with effacement of foot processes (collagen deposits)

Findings

1) Focal Segmental Sclerosis on H&E
2) EM Effacement of Podocytes
3) No immune complex deposits (or IF)
4) Non-response to steroids

Question 25

Focal Segmental Glomerulosclerosis (FSGS) - Key Populations (4)

Answer 25

1) African + Hispanic Adults
2) HIV
3) Heroin Use
4) Sickle Cell

Question 26

Membranous Nephropathy - Cause + Findings (4)

Answer 26

1) Subepithelial (podocyte) deposits of immune complex with a spike and dome appearance on EM

Findings

1) Spike and Dome on EM - podocytes deposits new BM over-top the immune deposits
2) Thick Basement membrane on H&E
3) Poor response to steroids
4) Immune complex deposition that lights up on IF

Question 27

Membranous Nephropathy - Key Populations (5)

Answer 27

1) Caucasian Males
2) Hepatitis B/C
3) SLE
4) Tumors
5) Drugs (NSAIDs + Penicillin)

Question 28

Three Locations of Immune Deposition in Nephrotic Syndromes

Answer 28

1) Sub-Epithelial (Podocyte) - Membranous Nephropathy
2) Sub-Endothelial - Membranoproliferative Type I
3) Basement Membrane - Membranoproliferative Type II

Question 29

Membranoproliferative Glomerulonephritis - Cause + Types

Answer 29

Nephitic/Nephrotic Syndrome - Immune Complex Deposition

Type I - Subendothelial deposit
Type II - Dense Deposit Disease - BM Deposits due to C3 Convertase - Change in C3 Convertase prevents it from being turned off –> Overactivation of compliment (low circulating C3)

Question 30

Membranoproliferative Glomerulonephritis - Findings (4)

Answer 30

1) Tram Track Appearance on H&E due to the mesangeal cells spliting the BM
2) Immune Complex Deposition with IF Granules
3) Type II - Low Circulating C3
4) Poor Steroid Response

Question 31

Diabetes Induced Nephrotic Syndrome - Pathophysiology

Answer 31

High Serum Glucose - Non-Enzymatic Gycosylation of vascular BM - Efferent more affected than afferent - Leads to high GFR and Pressure leading to injury and albumin leak

Question 32

Diabetes Induced Nephrotic Syndrome - Key Finding + Key Treatment

Answer 32

1) Kimmelstiel Wilson Nodules - Mesangium sclerosis of “white” areas on the glomerulus on H&E - Patho-neumonic
2) Treat with ACE Inhibitors - slow progression of the damage + also hit AII which reduces efferent constriction

Question 33

Systemic Amyloidosis Induced Nephrotic Syndrome - Pathophysiology + Key Finding

Answer 33

Amyloid deposits in the mesangium resulting in apple green birefringence under polarized light with Congo Red Stain

Question 34

Basic Findings of Nephritic Syndrome

Answer 34

1) RBCs (Dysmorphic) and RBC Casts in Urine (Hematuria
2) Low Urine Volume (Oliguria)
3) Only Mild Proteinuria
4) Salt Retention + HTN
5) Hypercellular Glomerulus (Inflammation) with swelling into the Bowman’s Space on H&E

Question 35

Major Nephritic Syndromes (5)

Answer 35

1) Post-Strep Glomerulonephritis
2) Rapidly Progressing Glomerulonephritis
3) IgA Nephropathy
4) Alport Syndrome
5) Membranoproliferative Glomerulonephritis

Question 36

Post-Streptococcal Glomerulonephritis (PSGN) - Cause + Findings (6)

Answer 36

Cause - 2-3 Weeks after Group A B-Hemolytic Streptococcal Infection - with M-Protein Virulence Factor

Findings

1) Hematuria (Cola-Colored Urine)
2) Oliguria
3) HTN
4) Periorbital Edema
5) Hypercellular inflamed glomeruli on H&E
6) Sub-epithelial humps on EM due to complement mediated immune comple

Question 37

Rapidly Progressing Glomerulonephritis (RPGN) - Pathophysiology + Key Findings

Answer 37

Class of diseases - rapidly progressing complement mediated nephritis

Key Findings

1) Crescent shapes in the Bowman’s made of macrophages and fibrin
2) IF Patterns unique to each major cause

Question 38

Linear Immune Fluorescence in RPGN - Disease

Answer 38

Goodpasture Syndrome

Question 39

Granular Immune Fluorescence in RPGN - Disease (2)

Answer 39

1) Post-Strep GN with Progression

2) Diffuse Proliferative GN

Question 40

Negative Immune Fluorescence in RPGN - Disease (3) + Alternative Name

Answer 40

Pauci-Immune

1) Wegener Granulomatosis - cANCA
2) Microscopic Polyangiitis
3) Churg-Strauss - pANCA

Question 41

Goodpasture Syndrome - IF Pattern + Key Points (3)

Answer 41

Linear (Anti-BM Collagen Antibody) IF

Key Points

1) Usually with hemoptysis + hematuria
2) Young Males
3) Different from Wegner’s in that it doesn’t have sinus issues

Question 42

Diffuse Proliferative GN - IF Pattern + Key Points (2)

Answer 42

Granular Pattern (Like Post-Strep GN)

Key Points

1) Antigen-Antibody deposit (sub-endothelial)
2) Common in SLE

Question 43

Wegener’s Granulomatosis - IF Pattern + Key Points (2)

Answer 43

Negative IF with Positive c-ANCA

Key Points

1) Accompanying Lung Disease + Nasopharynx Disease
2) Different from Goodpasture in that it has nasopharyxn involvement

Question 44

Churg-Strauss - IF Pattern + Key Points (2)

Answer 44

Negative IF with Positive p-ANCA

Key Points

1) Triad - Granulomatous Inflammation + Eosinophilia + Asthma
2) Triad is key difference vs. Microscopic polyangiitis

Question 45

Microscopic Polyangitis - IF Pattern + Key Points (2)

Answer 45

Negative IF with Positive p-ANCA

Key Points
1) Missing triad is key difference vs. Churg-Strauss

Question 46

IgA Nephropathy - Cause + Key Findings (3)

Answer 46

Nephritic Syndrome - IgA Immune complex deposition in the mesangium of glomeruli

Findings

1) Presents during childhood with hematuria
2) Usually follows mucosal infection (e.g. gastroenteritis - IgA produced to fight mucosal infection)
3) Slow progression to renal failure

Question 47

Alport Syndrome - Cause + Key Findings (5)

Answer 47

Nephritic Syndrome - X-Linked Defect in Type IV Collagen

Findings

1) X-Linked
2) Thinning and Splitting of Glomerular BM
3) Isolated Hematuria
4) Hearing Loss + Ocular Disturbance (Affects Membranes)