SECTION 1: INTRODUCTION AND OVERVIEW 4 Introduction to Renal Pathology Robert B. Colvin, MD 24 Normal Kidney Structure Neeraja Kambham, MD and Anthony Chang, MD 36 Normal Kidney Development Sanjay Jain, MD, PhD 46 Kidney Biopsy Reports Surya V. Seshan, MD, Anthony Chang, MD, and Lynn D. Cornell, MD 48 Needle Biopsy: Evaluation for Adequacy Lynn D. Cornell, MD 52 Harmonized Nephropathology Terminology and Reporting Mark Haas, MD, PhD 54 Consensus Definitions of Light and Electron Microscopy Lesions Mark Haas, MD, PhD 58 Common Artifacts and Pitfalls Lynn D. Cornell, MD SECTION 2: GLOMERULAR DISEASES PODOCYTOPATHIES 66 Minimal Change Disease (Diffuse Podocytopathy) A. Brad Farris, III, MD, MBA and Astrid Weins, MD, PhD 74 Classification of Focal Segmental Glomerulosclerosis A. Brad Farris, III, MD, MBA and Astrid Weins, MD, PhD 78 Etiologic Classification of Focal Segmental Glomerulosclerosis Robert B. Colvin, MD 80 Focal Segmental Glomerulosclerosis, Primary A. Brad Farris, III, MD, MBA and Astrid Weins, MD, PhD 88 Focal Segmental Glomerulosclerosis, Adaptive (Secondary) A. Brad Farris, III, MD, MBA and Astrid Weins, MD, PhD 94 Collapsing Glomerulopathy A. Brad Farris, III, MD, MBA and Astrid Weins, MD, PhD MEMBRANOUS NEPHROPATHY AND VARIANTS 104 Introduction to Membranous Nephropathy Robert B. Colvin, MD and Anthony Chang, MD 112 Etiologies of Membranous Nephropathy Anthony Chang, MD and Robert B. Colvin, MD 114 Membranous Nephropathy Due to PLA2R1 Autoantibodies Anthony Chang, MD and Sanjeev Sethi, MD 120 Membranous Nephropathy Due to Non-PLA2R1 Autoantibodies Anthony Chang, MD and Sanjeev Sethi, MD 126 Membranous Nephropathy Associated With Systemic Disease Anthony Chang, MD 130 Membranous Nephropathy With Anti-TBM Antibodies Robert B. Colvin, MD 132 Podocyte Infolding Glomerulopathy Shane Meehan, MB, BCh IGA-RELATED GLOMERULONEPHRITIDES 134 Overview of IgA-Related Glomerular Diseases Shane Meehan, MB, BCh 138 IgA Nephropathy Lynn D. Cornell, MD, Robert B. Colvin, MD, and Ian Roberts, MBChB, FRCPath 152 IgA Vasculitis (Henoch-Schoenlein Purpura) Anthony Chang, MD and Ian Roberts, MBChB, FRCPath 158 IgA Acute Glomerulonephritis Associated With Staphylococcus aureus Robert B. Colvin, MD and Ian Roberts, MBChB, FRCPath 162 Hepatic Disease With IgA Deposition Robert B. Colvin, MD SLE AND RELATED AUTOANTIBODYMEDIATED DISEASES 164 Systemic Lupus Erythematosus Shane Meehan, MB, BCh, Robert B. Colvin, MD, and Ingeborg M. Bajema, MD, PhD 182 Mixed Connective Tissue Disease A. Brad Farris, III, MD, MBA 184 Idiopathic Nonlupus Full-House Nephropathy Ingeborg M. Bajema, MD, PhD and Emilie Rijnink, MD, PhD 186 Mixed Cryoglobulinemic Glomerulonephritis A. Brad Farris, III, MD, MBA and Charles E. Alpers, MD ANTI-GBM DISEASES 192 Anti-GBM Glomerulonephritis Anthony Chang, MD 200 Atypical Anti-GBM Disease Lynn D. Cornell, MD COMPLEMENT-RELATED GLOMERULONEPHRITIDES 204 Classification of MPGN and Complement-Related Diseases Jean Hou, MD, Robert B. Colvin, MD, and Mark Haas, MD, PhD 210 Dense Deposit Disease Jean Hou, MD, Mark Haas, MD, PhD, and A. Brad Farris, III, MD, MBA 218 C3 Glomerulonephritis Jean Hou, MD, Lynn D. Cornell, MD, and Mark Haas, MD, PhD 226 C1q Nephropathy Neeraja Kambham, MD 232 C4 Glomerulopathy Sanjeev Sethi, MD and Lynn D. Cornell, MD 234 Immune Complex Membranoproliferative Glomerulonephritis Jean Hou, MD, A. Brad Farris, III, MD, MBA, and Mark Haas, MD, PhD MONOCLONAL IMMUNOGLOBULIN GLOMERULAR DISEASES 242 Introduction to Diseases With Monoclonal Immunoglobulin Deposits Robert B. Colvin, MD 246 Monoclonal Immunoglobulin Deposition Disease Lynn D. Cornell, MD 254 Proliferative Glomerulonephritis With Monoclonal IgG Deposits Lynn D. Cornell, MD 258 Membranous Nephropathy With Masked IgG-Kappa Deposits Christopher P. Larsen, MD and Tiffany Caza, MD, PhD 262 Type I Cryoglobulinemic Glomerulonephritis Evan Farkash, MD, PhD and Robert B. Colvin, MD 266 Waldenstroem Macroglobulinemia Anthony Chang, MD 268 Crystalglobulin Glomerulonephritis Mariam Priya Alexander, MD 270 Light Chain Crystalline Podocytopathy Lynn D. Cornell, MD AMYLOIDOSIS 272 Amyloidosis Classification A. Brad Farris, III, MD, MBA and Sanjeev Sethi, MD 278 AL/AH Amyloidosis A. Brad Farris, III, MD, MBA and Sanjeev Sethi, MD 284 AA Amyloidosis A. Brad Farris, III, MD, MBA and Sanjeev Sethi, MD 288 AFib Amyloidosis A. Brad Farris, III, MD, MBA and Sanjeev Sethi, MD 290 AGel Amyloidosis Sanjeev Sethi, MD 292 ALECT2 Amyloidosis Christopher P. Larsen, MD, Sanjeev Sethi, MD, and Tiffany Caza, MD, PhD 294 AApoAI Amyloidosis A. Brad Farris, III, MD, MBA and Sanjeev Sethi, MD 295 AApoAII Amyloidosis Robert B. Colvin, MD and Sanjeev Sethi, MD 296 AApoAIV Amyloidosis Sanjeev Sethi, MD 297 AApoCII Amyloidosis Sanjeev Sethi, MD 298 ATTR Amyloidosis A. Brad Farris, III, MD, MBA and Sanjeev Sethi, MD IDIOPATHIC FIBRILLARY GLOMERULOPATHIES 300 Diseases With Organized Deposits Robert B. Colvin, MD 304 Fibrillary Glomerulopathy Anthony Chang, MD and Mariam Priya Alexander, MD 310 Immunotactoid Glomerulopathy Anthony Chang, MD and Charles E. Alpers, MD 314 Fibronectin Glomerulopathy Neeraja Kambham, MD DIABETIC AND RELATED RENAL DISEASES 318 Diabetic Nephropathy Neeraja Kambham, MD and Ian Roberts, MBChB, FRCPath 328 Metabolic Syndrome/Obesity-Related Glomerular Disease Shane Meehan, MB, BCh 332 Idiopathic Nodular Glomerulopathy A. Brad Farris, III, MD, MBA and Ian Roberts, MBChB, FRCPath INFECTION-RELATED GLOMERULAR DISEASES 336 Overview of Infection-Related Glomerular Disease Shane Meehan, MB, BCh 340 Acute Poststreptococcal Glomerulonephritis A. Brad Farris, III, MD, MBA 348 Postinfectious Glomerulonephritis, Nonstreptococcal A. Brad Farris, III, MD, MBA 354 Glomerulonephritis of Chronic Infection, Including Shunt Nephritis A. Brad Farris, III, MD, MBA 356 Endocarditis A. Brad Farris, III, MD, MBA and Christie L. Boils, MD 360 Syphilis Shane Meehan, MB, BCh 362 Lyme Disease Neeraja Kambham, MD 364 COVID-19 Nephropathies Lynn D. Cornell, MD, Mariam Priya Alexander, MD, and Robert B. Colvin, MD 372 Hepatitis B Virus Anthony Chang, MD 376 Hepatitis C Virus Anthony Chang, MD and Charles E. Alpers, MD 382 HIV-Associated Nephropathy A. Brad Farris, III, MD, MBA 388 Miscellaneous HIV-Associated Renal Diseases A. Brad Farris, III, MD, MBA 394 Schistosomiasis Neeraja Kambham, MD 396 Filariasis Christie L. Boils, MD 397 Leishmaniasis Kerstin Amann, MD and Robert B. Colvin, MD DRUG-INDUCED GLOMERULAR DISEASES 398 Drug-Induced Minimal Change Disease Anthony Chang, MD and Astrid Weins, MD, PhD 400 Bisphosphonate-Induced Collapsing Glomerulopathy A. Brad Farris, III, MD, MBA and Astrid Weins, MD, PhD 401 Chloroquine Toxicity Shane Meehan, MB, BCh 402 Antihepatitis C Virus Drugs Ivy A. Rosales, MD 406 Anti-EGFR Drugs Kammi J. Henriksen, MD GENETIC GLOMERULAR DISEASES 408 Classification of Glomerular Genetic Diseases Sanjay Jain, MD, PhD 410 Genetic Causes of Nephrotic Syndrome Joseph P. Gaut, MD, PhD GENETIC DISEASES OF GBM COLLAGEN 414 Alport Syndrome Joseph P. Gaut, MD, PhD, Helen Liapis, MD, and Robert B. Colvin, MD 426 Thin Basement Membrane Disease Joseph P. Gaut, MD, PhD and Helen Liapis, MD GENETIC PODOCYTE DISEASES 428 Congenital Nephrotic Syndrome of Finnish Type Joseph P. Gaut, MD, PhD and Helen Liapis, MD 432 Pierson Syndrome Nidia Messias, MD, Joseph P. Gaut, MD, PhD, and Helen Liapis, MD 434 Galloway-Mowat Syndrome Carrie L. Phillips, MD and Stephen M. Bonsib, MD 436 Denys-Drash Syndrome Kammi J. Henriksen, MD and Stephen M. Bonsib, MD 440 Frasier Syndrome Carrie L. Phillips, MD and Stephen M. Bonsib, MD 442 Podocin Deficiency Joseph P. Gaut, MD, PhD and Helen Liapis, MD 444 a-Actinin-4 Deficiency Joseph P. Gaut, MD, PhD and Helen Liapis, MD 446 Autosomal Dominant FSGS Due to INF2 Mutations Robert B. Colvin, MD 448 APOL1-Related Glomerular Disease Christopher P. Larsen, MD and Tiffany Caza, MD, PhD 452 Schimke Immunoosseous Dysplasia Shane Meehan, MB, BCh GENETIC STORAGE AND LIPID DISEASES 454 Fabry Disease Robert B. Colvin, MD and Laura Barisoni, MD 462 Alagille Syndrome Anthony Chang, MD 464 Lecithin Cholesterol Acyltransferase Deficiency Carrie L. Phillips, MD and Stephen M. Bonsib, MD 468 APOE Lipoprotein Glomerulopathy Joseph P. Gaut, MD, PhD and Helen Liapis, MD 470 Type III Hyperlipoproteinemia Nidia Messias, MD, Joseph P. Gaut, MD, PhD, and Helen Liapis, MD 472 I-Cell Disease (Mucolipidosis II) Carrie L. Phillips, MD and Stephen M. Bonsib, MD 474 Gaucher Glomerulopathy A. Brad Farris, III, MD, MBA OTHER GENETIC GLOMERULAR DISEASES 476 Type III Collagen Glomerulopathy Nidia Messias, MD, L. Nicholas Cossey, MD, and Helen Liapis, MD 480 Nail-Patella Syndrome Nidia Messias, MD and Helen Liapis, MD 482 Glomerulopathy of Hereditary Multiple Exostoses Robert B. Colvin, MD and Ian Roberts, MBChB, FRCPath MISCELLANEOUS GLOMERULAR DISEASES 484 Cryofibrinogenic Glomerulopathy Lynn D. Cornell, MD and Mariam Priya Alexander, MD 488 IgM Nephropathy Neeraja Kambham, MD 490 Kidney Disease Associated With COVID-19 Immunization Astrid Weins, MD, PhD and Robert B. Colvin, MD 494 Renal Disease in Rheumatoid Arthritis Neeraja Kambham, MD 500 Hemophagocytic Glomerulopathy Lynn D. Cornell, MD 504 Coenzyme-Q Nephropathies Laura Barisoni, MD 506 Hepatic Glomerulosclerosis Robert B. Colvin, MD 507 Intravascular Large B-Cell Lymphoma Anthony Chang, MD SECTION 3: VASCULAR DISEASES 510 Overview and Classification of Systemic Vasculitides Surya V. Seshan, MD and Ingeborg M. Bajema, MD, PhD ANCA DISEASES 520 ANCA-Related Glomerulonephritis Surya V. Seshan, MD and Ingeborg M. Bajema, MD, PhD 526 Microscopic Polyangiitis Surya V. Seshan, MD and Ingeborg M. Bajema, MD, PhD 534 Granulomatosis With Polyangiitis Surya V. Seshan, MD and Ingeborg M. Bajema, MD, PhD 544 Eosinophilic Granulomatosis With Polyangiitis (Churg-Strauss) Surya V. Seshan, MD and Ingeborg M. Bajema, MD, PhD 550 Drug-Induced ANCA Vasculitis Surya V. Seshan, MD and Ingeborg M. Bajema, MD, PhD NON-ANCA DISEASES 554 Polyarteritis Nodosa Surya V. Seshan, MD 560 Kawasaki Disease Surya V. Seshan, MD and Yael K. Heher, MD, MPH, FRCP(C) 562 Giant Cell Arteritis Surya V. Seshan, MD 566 Takayasu Arteritis Surya V. Seshan, MD 570 Hypocomplementemic Urticarial Vasculitis (Anti-C1q Vasculitis) Robert B. Colvin, MD THROMBOTIC MICROANGIOPATHIES 572 Introduction to Thrombotic Microangiopathies Neeraja Kambham, MD and Ivy A. Rosales, MD 578 Infection-Related Hemolytic Uremic Syndrome Neeraja Kambham, MD and Ivy A. Rosales, MD 584 Genetic Thrombotic Microangiopathy Neeraja Kambham, MD and Ivy A. Rosales, MD 588 Autoimmune Thrombotic Microangiopathy Neeraja Kambham, MD and Ivy A. Rosales, MD 592 Drug-Induced Thrombotic Microangiopathy Neeraja Kambham, MD and Ivy A. Rosales, MD 596 Postpartum Hemolytic Uremic Syndrome Neeraja Kambham, MD and Ivy A. Rosales, MD 600 Scleroderma Renal Disease Neeraja Kambham, MD and Ivy A. Rosales, MD 606 Multicentric Castleman Disease Lynn D. Cornell, MD OTHER DISEASES AFFECTING ENDOTHELIUM 608 Preeclampsia, Eclampsia, and HELLP Syndrome Anthony Chang, MD 610 Radiation Nephropathy Anthony Chang, MD 612 Sickle Cell Nephropathy Anthony Chang, MD 616 Retinal Vasculopathy and Cerebral Leukodystrophy Robert B. Colvin, MD HYPERTENSIVE RENAL DISEASES 618 Hypertensive Renovascular Diseases A. Brad Farris, III, MD, MBA 626 Renal Artery Stenosis A. Brad Farris, III, MD, MBA 630 Fibromuscular Dysplasia A. Brad Farris, III, MD, MBA 636 Neurofibromatosis Kammi J. Henriksen, MD and Stephen M. Bonsib, MD THROMBOTIC AND EMBOLIC DISEASES 640 Renal Vein Thrombosis Anthony Chang, MD and Yael K. Heher, MD, MPH, FRCP(C) 642 Renal Artery Thrombosis Anthony Chang, MD 644 Atheromatous Emboli Anthony Chang, MD 646 Hydrophilic Polymer Emboli Kammi J. Henriksen, MD SECTION 4: TUBULOINTERSTITIAL DISEASES 650 Overview and Classification of Tubulointerstitial Diseases Robert B. Colvin, MD 652 Differential Diagnosis of Acute Interstitial Nephritis Lynn D. Cornell, MD 658 Granulomatous Interstitial Nephritis Ivy A. Rosales, MD 662 Guide to Crystal Nephropathies L. Nicholas Cossey, MD ISCHEMIC INJURIES 668 Acute Tubular Injury Shane Meehan, MB, BCh 674 Renal Cortical Necrosis Shane Meehan, MB, BCh 676 Sepsis/Shock Joseph P. Gaut, MD, PhD IMMUNOLOGIC TUBULAR DISEASES 678 IgG4-Related Disease Lynn D. Cornell, MD 688 Sjoegren Syndrome Josephine M. Ambruzs, MD, MPH 692 Tubulointerstitial Nephritis and Uveitis A. Brad Farris, III, MD, MBA 696 Sarcoidosis Josephine M. Ambruzs, MD, MPH 700 Antibrush Border Autoantibody Tubulointerstitial Nephritis Ivy A. Rosales, MD and Robert B. Colvin, MD 702 Anti-TBM Disease Robert B. Colvin, MD 704 Tubulointerstitial Nephritis With IgM(+) Plasma Cells Lynn D. Cornell, MD MONOCLONAL IMMUNOGLOBULIN TUBULOINTERSTITIAL DISEASES 706 Light Chain Cast Nephropathy Anthony Chang, MD and Kammi J. Henriksen, MD 712 Light Chain Proximal Tubulopathy With Crystals Lynn D. Cornell, MD 716 Light Chain Proximal Tubulopathy Without Crystals Christopher P. Larsen, MD and Tiffany Caza, MD, PhD 720 Crystal-Storing Histiocytosis Mariam Priya Alexander, MD DRUG-INDUCED TUBULOINTERSTITIAL DISEASES 724 Drug-Induced Acute Interstitial Nephritis Lynn D. Cornell, MD and Robert B. Colvin, MD 730 Drugs That Cause Tubulointerstitial Nephritis Robert B. Colvin, MD and Lynn D. Cornell, MD 732 Checkpoint Inhibitor-Induced Kidney Diseases Ivy A. Rosales, MD 736 Papillary Necrosis Neeraja Kambham, MD 740 Cisplatin Nephrotoxicity Shane Meehan, MB, BCh 742 Osmotic Tubulopathy Shane Meehan, MB, BCh and Evan Farkash, MD, PhD 746 Antiviral Drug Nephrotoxicity Shane Meehan, MB, BCh 752 Acute Phosphate Nephropathy Lynn D. Cornell, MD 754 Lithium-Induced Renal Disease Anthony Chang, MD and Yael K. Heher, MD, MPH, FRCP(C) 756 Calcineurin Inhibitor Toxicity Shane Meehan, MB, BCh 762 mTOR Inhibitor Toxicity Lynn D. Cornell, MD 764 Vancomycin-Induced Cast Nephropathy Kammi J. Henriksen, MD 766 Anticoagulant-Related Nephropathy Christopher P. Larsen, MD and Tiffany Caza, MD, PhD 768 Illicit Drugs and Opioids Kammi J. Henriksen, MD TOXIC TUBULOPATHIES 770 Myoglobinuria/Rhabdomyolysis/Hemoglobinuria Neeraja Kambham, MD 772 Bile Cast Nephropathy Anthony Chang, MD 774 Lead and Other Heavy Metal Toxins Shane Meehan, MB, BCh 778 Ethylene Glycol Toxicity Shane Meehan, MB, BCh 780 Aristolochic Acid Nephropathy Shane Meehan, MB, BCh 782 Balkan Endemic Nephropathy Shane Meehan, MB, BCh 784 Argyria Robert B. Colvin, MD AUTOSOMAL DOMINANT TUBULOINTERSTITIAL KIDNEY DISEASES 786 MUC1-Related Autosomal Dominant Tubulointerstitial Kidney Disease Joseph P. Gaut, MD, PhD and Helen Liapis, MD 788 UMOD-Related Autosomal Dominant Tubulointerstitial Kidney Disease Shane Meehan, MB, BCh 790 REN-Related Autosomal Dominant Tubulointerstitial Kidney Disease Lynn D. Cornell, MD 792 HNF1B-Related Autosomal Dominant Tubulointerstitial Kidney Disease Robert B. Colvin, MD and Marie Claire Gubler, MD GENETIC CRYSTAL DEPOSITION DISEASES 794 Uric Acid Nephropathy/Gout Shane Meehan, MB, BCh 798 Primary Hyperoxaluria Shane Meehan, MB, BCh 800 2,8-Dihydroxyadeninuria Lynn D. Cornell, MD 802 Cystinosis Nidia Messias, MD, Joseph P. Gaut, MD, PhD, and Helen Liapis, MD GENETIC TRANSPORT DISEASES 804 Bartter Syndrome Shane Meehan, MB, BCh 806 Dent Disease Lynn D. Cornell, MD 808 Oculocerebrorenal Syndrome of Lowe Josephine M. Ambruzs, MD, MPH OTHER GENETIC TUBULAR DISEASES 810 Mitochondriopathies Surya V. Seshan, MD 814 Systemic Karyomegaly Robert B. Colvin, MD 816 Methylmalonic Acidemia Lynn D. Cornell, MD and Linda Hasadsri, MD, PhD MISCELLANEOUS TUBULOINTERSTITIAL DISEASES 820 Nephrocalcinosis Lynn D. Cornell, MD 822 Lysozyme Nephropathy Tiffany Caza, MD, PhD and Christopher P. Larsen, MD 824 Secondary Oxalosis Lynn D. Cornell, MD 826 Chronic Interstitial Nephritis in Agricultural Communities Lynn D. Cornell, MD 828 Extramedullary Hematopoiesis Lynn D. Cornell, MD SECTION 5: KIDNEY INFECTIONS BACTERIAL INFECTIONS 834 Acute Pyelonephritis Neeraja Kambham, MD 842 Chronic Pyelonephritis Neeraja Kambham, MD 846 Xanthogranulomatous Pyelonephritis Neeraja Kambham, MD and Ivy A. Rosales, MD 850 Malakoplakia Neeraja Kambham, MD 854 Tuberculosis Neeraja Kambham, MD 856 BCG Granulomatous Interstitial Nephritis Neeraja Kambham, MD 858 Leprosy Neeraja Kambham, MD 859 Megalocytic Interstitial Nephritis Neeraja Kambham, MD 860 Nocardiosis Neeraja Kambham, MD 862 Leptospirosis Shane Meehan, MB, BCh 864 Whipple Disease Carrie L. Phillips, MD FUNGAL, RICKETTSIAL, AND PARASITIC INFECTIONS 866 Mucormycosis Anthony Chang, MD 868 Candidiasis Anthony Chang, MD 869 Histoplasmosis Anthony Chang, MD 870 Coccidioidomycosis Anthony Chang, MD 871 Blastomycosis Anthony Chang, MD 872 Paracoccidioidomycosis Anthony Chang, MD 873 Aspergillosis Anthony Chang, MD 874 Cryptococcosis Anthony Chang, MD 875 Microsporidiosis Robert B. Colvin, MD 876 Rickettsial Infections Shane Meehan, MB, BCh 878 Toxoplasmosis Neeraja Kambham, MD 880 Hydatidosis Carrie L. Phillips, MD and Stephen M. Bonsib, MD VIRAL INFECTIONS 882 Polyomavirus Nephritis Anthony Chang, MD and Evan Farkash, MD, PhD 890 Cytomegalovirus Infection Anthony Chang, MD and R. Neal Smith, MD, PhD 892 Adenovirus Infection Anthony Chang, MD and R. Neal Smith, MD, PhD 894 Epstein-Barr Virus Nephritis Anthony Chang, MD and R. Neal Smith, MD, PhD 896 Herpes Simplex Acute Nephritis Anthony Chang, MD and R. Neal Smith, MD, PhD 898 Hantavirus Nephropathy A. Brad Farris, III, MD, MBA SECTION 6: DEVELOPMENTAL DISEASES 902 Overview of Congenital Anomalies of Kidney and Urinary Tract Sanjay Jain, MD, PhD 906 Dysplasia/Hypoplasia/Agenesis Sanjay Jain, MD, PhD 912 Oligomeganephronia Robert B. Colvin, MD and Yael K. Heher, MD, MPH, FRCP(C) 914 Ectopia, Malrotation, Duplication, Fusion, Supernumerary Kidney Sanjay Jain, MD, PhD 918 Ask-Upmark Kidney Lynn D. Cornell, MD 920 Renal Tubular Dysgenesis Carrie L. Phillips, MD and Stephen M. Bonsib, MD SECTION 7: CYSTIC DISEASES 926 Overview of Cystic Diseases Nidia Messias, MD, Joseph P. Gaut, MD, PhD, and Helen Liapis, MD CILIOPATHIES 932 Autosomal Dominant Polycystic Kidney Disease Anthony Chang, MD, Robert B. Colvin, MD, and Yael K. Heher, MD, MPH, FRCP(C) 938 Autosomal Recessive Polycystic Kidney Disease Carrie L. Phillips, MD and Stephen M. Bonsib, MD 944 Nephronophthisis and Related Ciliopathies Kerstin Amann, MD, Helen Liapis, MD, and Robert B. Colvin, MD OTHER GENETIC CYSTIC DISEASES 950 von Hippel-Lindau Disease Carrie L. Phillips, MD and Stephen M. Bonsib, MD 956 Tuberous Sclerosis Complex Christie L. Boils, MD 962 Zellweger Syndrome Carrie L. Phillips, MD and Stephen M. Bonsib, MD MISCELLANEOUS CYSTIC DISEASES 964 Medullary Sponge Kidney Lynn D. Cornell, MD 966 Mixed Epithelial and Stromal Tumor Family Carrie L. Phillips, MD and Stephen M. Bonsib, MD 972 Pediatric Cystic Nephroma Angelica R. Putnam, MD and Carrie L. Phillips, MD 976 Acquired Cystic Disease Carrie L. Phillips, MD and Stephen M. Bonsib, MD 980 Simple and Miscellaneous Cysts Anthony Chang, MD 982 Renal Lymphangioma/Lymphangiectasia Carrie L. Phillips, MD and Stephen M. Bonsib, MD SECTION 8: COLLECTING SYSTEM DISEASES 988 Introduction to Impediments to Urine Flow Sanjay Jain, MD, PhD 992 Reflux Nephropathy Sanjay Jain, MD, PhD 996 Obstructive Uropathy Sanjay Jain, MD, PhD 1000 Nephrolithiasis Shane Meehan, MB, BCh 1006 Loin Pain Hematuria Syndrome Carrie L. Phillips, MD and Stephen M. Bonsib, MD SECTION 9: RENAL ALLOGRAFT DISEASES 1010 Pathologic Classification of Renal Allograft Diseases Robert B. Colvin, MD INTRODUCTION 1012 Evaluation of Allograft Kidneys Lynn D. Cornell, MD and Evan Farkash, MD, PhD 1018 Evaluation of Donor Kidneys Lynn D. Cornell, MD and Evan Farkash, MD, PhD REJECTION 1024 Acute T-Cell-Mediated Rejection Lynn D. Cornell, MD and Michael Mengel, MD 1034 Chronic T-Cell-Mediated Rejection Lynn D. Cornell, MD and Michael Mengel, MD 1038 Hyperacute Rejection Lynn D. Cornell, MD and Michael Mengel, MD 1042 Acute Antibody-Mediated Rejection Lynn D. Cornell, MD and Michael Mengel, MD 1050 Chronic Antibody-Mediated Rejection Lynn D. Cornell, MD and Michael Mengel, MD 1062 Transcript Analysis of Renal Transplant Biopsies Michael Mengel, MD and R. Neal Smith, MD, PhD RECURRENT AND DE NOVO DISEASES 1066 Diseases That Recur in Allografts Anthony Chang, MD, Lynn D. Cornell, MD, and R. Neal Smith, MD, PhD 1072 De Novo Focal Segmental Glomerulosclerosis Anthony Chang, MD and Astrid Weins, MD, PhD 1074 De Novo Membranous Nephropathy Anthony Chang, MD 1078 Anti-GBM Disease in Alport Syndrome Anthony Chang, MD and R. Neal Smith, MD, PhD 1080 Chimerism Transition Syndrome A. Brad Farris, III, MD, MBA 1082 Late Posttransplant Histology Lynn D. Cornell, MD OTHER ALLOGRAFT DISEASES 1084 Acute Allograft Ischemia A. Brad Farris, III, MD, MBA 1088 Size Mismatch Allograft Injury Anthony Chang, MD and Yael K. Heher, MD, MPH, FRCP(C) 1090 Lymphocele A. Brad Farris, III, MD, MBA 1091 Transplant Renal Artery Stenosis A. Brad Farris, III, MD, MBA 1092 Transplant Renal Artery or Vein Thrombosis A. Brad Farris, III, MD, MBA 1094 Posttransplant Lymphoproliferative Diseases A. Brad Farris, III, MD, MBA 1104 BK Polyomavirus Neoplasia Evan Farkash, MD, PhD 1106 Protocol Biopsies Lynn D. Cornell, MD and Evan Farkash, MD, PhD 1110 Tolerance Robert B. Colvin, MD 1114 Kidney Xenografts Ivy A. Rosales, MD KIDNEY PATHOLOGY IN RECIPIENTS OF OTHER TRANSPLANTS 1118 Kidney Diseases in Nonrenal Transplant Recipients Robert B. Colvin, MD 1122 Graft-vs.-Host Glomerulopathies Anthony Chang, MD and Yael K. Heher, MD, MPH, FRCP(C) SECTION 10: KIDNEY EXAMINATION 1126 Examination of End-Stage Kidneys Shane Meehan, MB, BCh 1132 Examination of Tumor Nephrectomy Specimens for Nonneoplastic Diseases Kammi J. Henriksen, MD and Stephen M. Bonsib, MD 1136 Evaluation of Transplant Nephrectomies Shane Meehan, MB, BCh and Evan Farkash, MD, PhD 1140 Evaluation of Autopsy Kidneys Kammi J. Henriksen, MD and Mariam Priya Alexander, MD SECTION 11: TECHNIQUES 1146 Basic Concepts for Computational Image Analysis Laura Barisoni, MD and Andrew Janowczyk, PhD 1150 Artificial Intelligence and Digital Pathology Analysis of Kidneys A. Brad Farris, III, MD, MBA 1154 Evaluation of Fibrosis A. Brad Farris, III, MD, MBA 1158 Immunofluorescence on Paraffin Tissue Sections Nidia Messias, MD 1162 EM Processing From Paraffin Tissue A. Brad Farris, III, MD, MBA 1164 Detection of Autoantigens in Membranous Nephropathy Christopher P. Larsen, MD and A. Bernard Collins, BS 1168 Alport Collagen IV Immunofluorescence A. Bernard Collins, BS, Christopher P. Larsen, MD, and Robert B. Colvin, MD 1170 C4d Immunohistochemistry/Immunofluorescence Robert B. Colvin, MD and A. Bernard Collins, BS 1174 Polyomavirus Detection in Tissue Robert B. Colvin, MD 1176 Mass Spectrometry Sanjeev Sethi, MD and Mariam Priya Alexander, MD 1178 Diagnostic Genetics of Kidney Diseases Sanjay Jain, MD, PhD and Yasar Caliskan, MD