Study guide
5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis
ABIM Internal Medicine Exam
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1 Chapter 0: The ABIM Exam, Blueprint & Study Strategy
0.1 Exam Format, Question Types & the 2026 Blueprint 0.2 Eligibility, Registration, Fees & Exam-Day Logistics 0.3 Scoring, the Passing Standard & Score Reports 0.4 Building a Blueprint-Weighted Study Plan
2 Chapter 1: Cardiovascular Disease (14% of Exam)
1.1 Ischemic Heart Disease & Acute Coronary Syndromes 1.2 Antithrombotic Therapy, Secondary Prevention & Mechanical Complications of MI 1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention 1.4 Supraventricular Tachycardias, Ventricular Arrhythmias & Bradycardias 1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy 1.6 Device Therapy, HFpEF & the Cardiomyopathies 1.7 Valvular Heart Disease & Endocarditis Prophylaxis 1.8 Pericardial Disease & Acute Aortic Syndromes 1.9 Hypertension: Classification, Diagnosis & Secondary Causes 1.10 Hypertensive Crises & Dyslipidemia 1.11 Adult Congenital Heart Disease & Coarctation of the Aorta 1.12 Syncope: Reflex, Orthostatic & Cardiac Causes 1.13 Cardiac Physical Examination, Murmurs & Antithrombotic Selection
3 Chapter 2: Endocrinology, Diabetes & Metabolism (9% of Exam)
2.1 Diabetes Mellitus: Diagnosis, Glycemic Targets & Pharmacotherapy 2.2 Insulin Therapy, Hyperglycemic Emergencies & Chronic Complications 2.3 Thyroid Function Testing & Hypothyroidism 2.4 Thyrotoxicosis, Thyroid Storm & Thyroid Nodules 2.5 Adrenal & Pituitary Disorders 2.6 Hypercalcemia, Hypocalcemia & Disorders of Mineral Metabolism 2.7 Osteoporosis & Paget Disease of Bone 2.8 Ovarian, Testicular & Reproductive Endocrine Disorders 2.9 Hypoglycemia, Endocrine Tumors, Polyglandular Syndromes & Severe Hypertriglyceridemia
4 Chapter 3: Gastroenterology & Hepatology (9% of Exam)
3.1 Esophageal Disease 3.2 Stomach & Duodenal Disease and Gastrointestinal Hemorrhage 3.3 Inflammatory Bowel Disease 3.4 Celiac Disease & Irritable Bowel Syndrome 3.5 Diverticular Disease & Colorectal Cancer Screening 3.6 Viral Hepatitis, Steatotic & Alcohol-Associated Liver Disease 3.7 Cirrhosis & the Complications of Portal Hypertension 3.8 Acute Pancreatitis 3.9 Chronic Pancreatitis & Biliary Tract Disease 3.10 Inherited, Autoimmune & Drug-Induced Liver Disease 3.11 Small Intestinal Disease, Ischemia & Gastrointestinal Complications of HIV
5 Chapter 4: Infectious Disease (9% of Exam)
4.1 Lower Respiratory Tract Infections & Sepsis Syndromes 4.2 Viral Respiratory Pathogens & Tuberculosis 4.3 Central Nervous System Infections 4.4 Skin, Soft Tissue, Bone & Joint Infections 4.5 Infective Endocarditis & Cardiovascular Infection 4.6 Clostridioides difficile & Catheter-Related Bloodstream Infection 4.7 HIV Diagnosis, Antiretroviral Therapy & Prevention 4.8 Opportunistic Infections & Sexually Transmitted Infections 4.9 Fever of Unknown Origin, Neutropenic Fever & Toxic Shock 4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks 4.11 Infection Prevention, Nosocomial Infection & Postexposure Prophylaxis 4.12 Rheumatic Fever, Poststreptococcal Disease, Enteric & Hepatic Infections
6 Chapter 5: Pulmonary Disease (9% of Exam)
5.1 COPD: Diagnosis, GOLD Classification & Initial Pharmacotherapy 5.2 Interventions That Reduce COPD Mortality & Exacerbation Management 5.3 Asthma: Diagnosis, Stepwise Therapy & Status Asthmaticus 5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis 5.5 Sarcoidosis, Hypersensitivity Pneumonitis & Occupational Lung Disease 5.6 Pulmonary Embolism: Diagnosis, Risk Stratification & Anticoagulation 5.7 Pulmonary Hypertension & Sleep-Disordered Breathing 5.8 Acute Respiratory Distress Syndrome & Mechanical Ventilation 5.9 Pleural Disease, Empyema & Pneumothorax 5.10 Bronchiectasis, Cystic Fibrosis & Restrictive Lung Disease 5.11 Evaluation of Cough, Dyspnea, Hemoptysis & the Solitary Pulmonary Nodule
7 Chapter 6: Rheumatology & Orthopedics (9% of Exam)
6.1 Rheumatoid Arthritis: Diagnosis & Systemic Manifestations 6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies 6.3 Gout: Pathophysiology & Acute Management 6.4 Urate-Lowering Therapy & Calcium Pyrophosphate Deposition Disease 6.5 Osteoarthritis 6.6 Systemic Lupus Erythematosus 6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies 6.8 The Vasculitides 6.9 Regional Musculoskeletal Syndromes, Back Pain & Sports Injuries 6.10 Other Primary Rheumatic Disorders & Mixed Connective Tissue Disease 6.11 Osteonecrosis & Metabolic Bone Disease
8 Chapter 7: Hematology (6% of Exam)
7.1 Approach to Anemia & the Microcytic Anemias 7.2 Macrocytic, Normocytic & Hemolytic Anemias 7.3 Hemoglobinopathies, Thalassemias & Paroxysmal Nocturnal Hemoglobinuria 7.4 Platelet Disorders, Thrombocytopenia & the Bleeding Patient 7.5 Coagulation Factor Disorders, Thrombophilia & Anticoagulant Reversal 7.6 Acute Leukemias, Chronic Leukemias & Myeloproliferative Neoplasms 7.7 Lymphomas & Plasma Cell Disorders 7.8 Myelodysplastic Syndrome, Myeloproliferative Neoplasms & Porphyria 7.9 Transfusion Medicine & Late Complications of Transplantation
9 Chapter 8: Medical Oncology (6% of Exam)
8.1 Breast, Lung, Colorectal & Prostate Cancer 8.2 Oncologic Emergencies 8.3 Genitourinary & Gynecologic Malignancies 8.4 Head and Neck, Bone & Soft Tissue Cancer and Cancer of Unknown Primary 8.5 Complications of Cancer & Its Treatment 8.6 Cancer Prevention, Survivorship & Psychosocial Care
10 Chapter 9: Nephrology & Urology (6% of Exam)
9.1 Acute Kidney Injury: Staging, Etiology & Urine Microscopy 9.2 Glomerular Disorders & Nephrotic Syndrome 9.3 Nephritic Syndromes, RPGN & Indications for Renal Replacement Therapy 9.4 Chronic Kidney Disease: Staging & Progression Retardation 9.5 Complications of Chronic Kidney Disease: Anemia, CKD-MBD & Acidosis 9.6 Hyponatremia, Hypernatremia & Water Balance 9.7 Potassium Disorders & Systematic Acid-Base Analysis 9.8 Renal Tubular Acidosis & Nephrolithiasis 9.9 Prostate Disorders, Urinary Incontinence & Other Urologic Conditions 9.10 Cystic Kidney Disease, Obstructive Uropathy, Tubulointerstitial Disease & Hematuria
11 Chapter 10: Neurology (4% of Exam)
10.1 Acute Ischemic Stroke: Syndromes & Reperfusion 10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke 10.3 Headache & Facial Pain 10.4 Seizures, Epilepsy & Movement Disorders 10.5 Multiple Sclerosis & Neuromuscular Junction Disorders 10.6 Motor Neuron Disease & Acute Peripheral Neuropathy 10.7 Cranial Neuropathies & Neuro-Ophthalmology 10.8 Peripheral Neuropathies, CNS Tumors & Other Neurologic Disorders
12 Chapter 11: Psychiatry & Behavioral Health (4% of Exam)
11.1 Major Depressive Disorder & Medical Mimics 11.2 Antidepressant Pharmacotherapy & Treatment-Resistant Depression 11.3 Bipolar Disorder, Mood Stabilizers & Lithium Toxicity 11.4 Anxiety, Stress-Related & Obsessive-Compulsive Disorders 11.5 Alcohol Use Disorder & Withdrawal 11.6 Pharmacotherapy for Alcohol & Opioid Use Disorder 11.7 Toxidromes, Psychiatric Emergencies & Suicide Risk Assessment 11.8 Psychotic, Somatic Symptom, Factitious & Personality Disorders 11.9 Eating Disorders, Sleep Disorders & Sexual Health
13 Chapter 12: Dermatology (3% of Exam)
12.1 Dermatitis, Papulosquamous & Inflammatory Dermatoses 12.2 Acne, Rosacea & Cutaneous Infections 12.3 Herpes Zoster & Autoimmune Blistering Diseases 12.4 Nodules, Tumors & Cutaneous Oncology 12.5 Dermatologic Emergencies & Severe Cutaneous Adverse Reactions 12.6 Pigment Disorders, Alopecia, Nail Disease & Photosensitivity 12.7 Vascular Dermatoses, Environmental Injury & Cutaneous Signs of Systemic Disease
14 Chapter 13: Obstetrics & Gynecology / Women's Health (3% of Exam)
13.1 Contraception, Preconception Care & Teratogenicity 13.2 Hypertensive Disorders of Pregnancy & Gestational Diabetes 13.3 Thyroid Disease & Venous Thromboembolism in Pregnancy 13.4 Menopause & Menopausal Hormone Therapy 13.5 Abnormal Uterine Bleeding, Endometrial Disease & Gynecologic Cancer Screening 13.6 Breast Disorders & Diseases of the Vulva and Vagina 13.7 Menstrual Disorders, Fibroids, Endometriosis & Early Pregnancy Complications
15 Chapter 14: Geriatric Syndromes (3% of Exam)
14.1 Comprehensive Geriatric Assessment & Frailty 14.2 Falls, Gait Assessment & Polypharmacy 14.3 Urinary Incontinence & Pressure Injuries in Older Adults 14.4 Mild Cognitive Impairment, Dementia & Its Subtypes 14.5 Delirium & the Pharmacotherapy of Cognitive Disorders 14.6 Palliative Care, Hospice & Advance Care Planning 14.7 Chronic Wounds, Nutrition, Swallowing, Constipation & Hip Fracture 14.8 Sensory Impairment, Dizziness, Elder Mistreatment & Care Settings
16 Chapter 15: Allergy & Immunology (2% of Exam)
15.1 Anaphylaxis: Recognition & Emergency Management 15.2 Urticaria & Angioedema 15.3 Drug Allergy, Desensitization & Adult Immunodeficiency 15.4 Food Allergy, Insect Venom Hypersensitivity, Serum Sickness & Contrast Reactions 15.5 Rhinitis, Conjunctivitis, Eosinophilic & Mast Cell Disorders
17 Chapter 16: Preventive Medicine, Immunization & Clinical Epidemiology
16.1 The USPSTF Framework & Evidence-Based Cancer Screening 16.2 Cardiovascular & Metabolic Screening and Primary Prevention 16.3 Adult Immunization & Vaccines in Special Populations 16.4 Clinical Epidemiology, Biostatistics & Study Design
18 Chapter 17: Miscellaneous - Ethics, Patient Safety & Quality Improvement (2% of Exam)
17.1 Principles of Bioethics & Decisional Capacity 17.2 Informed Consent, Treatment Refusal & Special Scenarios 17.3 Surrogate Decision-Making, Advance Directives & Confidentiality 17.4 Patient Safety Science, Medical Error & Diagnostic Reasoning 17.5 Quality Improvement Methods, Health Disparities & Health Equity
19 Chapter 18: Perioperative Medicine & Medical Consultation
18.1 Preoperative Cardiovascular Risk Assessment 18.2 Preoperative Pulmonary Risk & Perioperative Medication Management 18.3 Perioperative Anticoagulation, Bridging & Postoperative Complications
20 Chapter 19: Ophthalmology (1% of Exam)
19.1 The Acute Red Eye & Ophthalmic Emergencies 19.2 Painless Vision Loss & Chronic Ophthalmic Disease 19.3 Uveitis, Scleritis & Orbital Disease
21 Chapter 20: Otolaryngology & Dental Medicine (1% of Exam)
20.1 Dizziness, Vertigo & Epistaxis 20.2 Ear Disorders, Hearing Loss & Upper Respiratory Infections 20.3 Oral Cavity, Salivary Gland, Laryngeal & Taste and Smell Disorders
5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis
Key Takeaways Explain This Topic AI
Idiopathic pulmonary fibrosis, sarcoidosis, radiation pneumonitis, drug-induced disease, connective tissue disease and eosinophilic pneumonia are enumerated interstitial lung disease topics.
A definite usual interstitial pneumonia pattern on high-resolution computed tomography can establish idiopathic pulmonary fibrosis without surgical lung biopsy.
Antifibrotic therapy slows decline in forced vital capacity in idiopathic pulmonary fibrosis but does not reverse fibrosis.
Immunosuppression with prednisone, azathioprine and N-acetylcysteine increases mortality in idiopathic pulmonary fibrosis and is contraindicated.
Every new interstitial lung disease evaluation requires a detailed occupational, environmental, medication and connective tissue disease history.
Last updated: August 2026
Interstitial lung diseases (ILDs) comprise a broad group of non-neoplastic disorders characterized by progressive inflammation and/or fibrosis of the pulmonary parenchyma and alveolar septa. On the ABIM exam, candidates must master the diagnostic integration of pulmonary function testing, high-resolution computed tomography (HRCT), clinical syndromic patterns, occupational exposures, and modern antifibrotic versus immunosuppressive therapeutics.
- 1. Diagnostic Approach to Interstitial Lung Disease
- Pulmonary Function Testing (PFT) Patterns in ILD
Restrictive Ventilatory Defect: Hallmark finding characterized by a reduction in Total Lung Capacity (TLC < 80% predicted) and Forced Vital Capacity (FVC < 80% predicted) .
Airflow Ratios: The FEV1/FVC ratio is normal or elevated (> 0.75–0.80) due to increased radial parenchymal traction holding airways open.
Gas Exchange Impairment: Disproportionate reduction in the Diffusing Capacity of the Lung for Carbon Monoxide (DLCO < 70% predicted) due to alveolar-capillary membrane thickening and capillary bed obliteration. DLCO reduction often precedes FVC decline and correlates with exertional oxygen desaturation.
High-Resolution CT (HRCT) Imaging Protocol
Thin-slice (<=1 mm) volumetric imaging at full inspiration, supplemented with expiratory scans (to detect mosaic attenuation and air-trapping in hypersensitivity pneumonitis or bronchiolitis) and prone imaging (to distinguish true subpleural interstitial fibrosis from dependent atelectasis).
HRCT Pattern Dominant Radiologic Features Classical Etiologies
Usual Interstitial Pneumonia (UIP) Subpleural and basilar predominance, reticular opacities, honeycombing (stacked thick-walled cysts 3–10 mm), traction bronchiectasis; absence of inconsistent features (no extensive ground-glass). Idiopathic Pulmonary Fibrosis (IPF), Chronic Hypersensitivity Pneumonitis, Rheumatoid Arthritis-ILD, Asbestosis.
Non-Specific Interstitial Pneumonia (NSIP) Symmetric, basilar-predominant ground-glass opacities with fine reticulation, traction bronchiectasis, and subpleural sparing (sparing of immediate 1–3 mm subpleural space); minimal/absent honeycombing. Systemic Sclerosis (SSc), Polymyositis/Dermatomyositis, Mixed Connective Tissue Disease (MCTD), Idiopathic NSIP.
Hypersensitivity Pneumonitis (HP) Centrilobular diffuse ground-glass nodules, mosaic perfusion, and expiratory air-trapping ( "headcheese sign" / three-density sign combining lucent air-trapping, normal lung, and ground glass). Bird fancier's lung (avian antigen), Farmer's lung ( S. rectivirgula ), Hot tub lung ( M. avium ).
Organizing Pneumonia (OP / COP) Patchy, bilateral, migratory subpleural and peribronchovascular consolidations and ground glass; reverse halo / Atoll sign (central ground-glass surrounded by a crescentic or ring-like consolidation). Cryptogenic Organizing Pneumonia (COP), post-infectious, drug toxicity (Amiodarone, Bleomycin, Nitrofurantoin), SLE.
2. Idiopathic Pulmonary Fibrosis (IPF)
IPF is a specific form of chronic, progressive, fibrosing interstitial pneumonia of unknown etiology occurring primarily in older adults and limited to the lungs.
Clinical Presentation
Demographics: Age > 60 years (rare <50 years), male-to-female ratio ~2:1, strong association with cigarette smoking (>20 pack-years).
Symptoms & Signs: Insidious onset of progressive exertional dyspnea (>6 months) and chronic dry, non-productive cough. Physical examination reveals bilateral bibasilar fine end-inspiratory "Velcro-like" crackles (present in >95%) and digital clubbing (40–50%).
Diagnosis: The Definitive UIP Pattern
When HRCT demonstrates a Definite UIP Pattern (subpleural/basilar reticular opacities, honeycombing +/- traction bronchiectasis, absence of features inconsistent with UIP) in a patient with compatible clinical features and no identifiable secondary cause (no connective tissue disease, no environmental/drug exposures), a diagnosis of IPF is established without surgical lung biopsy .
Surgical lung biopsy (VATS) is reserved exclusively for cases with indeterminate or non-diagnostic HRCT patterns in surgical candidates.
Pharmacotherapy and Contraindications
Approved Antifibrotic Therapies:
Pirfenidone: Oral pyridone agent with pleiotropic antifibrotic, antioxidant, and anti-inflammatory properties; downregulates TGF-beta and procollagen production. Adverse effects: photosensitivity rash (requires sunscreen), nausea, dyspepsia, elevated transaminases.
Nintedanib: Oral intracellular tyrosine kinase inhibitor that targets Platelet-Derived Growth Factor Receptor (PDGFR), Fibroblast Growth Factor Receptor (FGFR), and Vascular Endothelial Growth Factor Receptor (VEGFR). Proven in the INPULSIS and TOMORROW trials to slow the annual rate of FVC decline by ~50% and reduce acute IPF exacerbations. Adverse effects: diarrhea (>60%; managed with Loperamide), nausea, hepatotoxicity (monitor LFTs monthly for first 3 months).
CRITICAL CONTRAINDICATION — The PANTHER Trial:
The landmark PANTHER-IPF trial demonstrated that "triple immunosuppressive therapy" with Prednisone + Azathioprine + N-Acetylcysteine (NAC) caused a statistically significant increase in all-cause mortality, hospitalizations, and serious adverse events compared to placebo. Immunosuppression is strictly contraindicated in IPF .
Non-Pharmacologic Management: Early referral for lung transplantation evaluation (IPF carries a median untreated survival of 3–5 years), supplemental oxygen for exertional or resting hypoxemia, pulmonary rehabilitation, and management of comorbid GERD (microaspiration accelerates fibrosis).