Study guide
6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies
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
6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies
Key Takeaways Explain This Topic AI
Ankylosing spondylitis, reactive arthritis, psoriatic arthritis and enteropathic arthritis are enumerated under spondyloarthropathies.
Methotrexate is the anchor disease-modifying drug and requires folic acid supplementation with monitoring of blood counts and liver enzymes.
Latent tuberculosis and hepatitis B screening are mandatory before tumor necrosis factor inhibitor therapy.
Non-steroidal anti-inflammatory drugs plus exercise are first-line in axial spondyloarthritis, with tumor necrosis factor or interleukin-17 inhibitors for inadequate response.
Conventional disease-modifying drugs such as methotrexate are ineffective for axial disease although they help peripheral arthritis.
Last updated: August 2026
1. Pharmacotherapy for Rheumatoid Arthritis
The modern management of RA employs an aggressive Treat-to-Target (T2T) strategy aiming for clinical remission (e.g., Clinical Disease Activity Index [CDAI] <=2.8) or low disease activity (CDAI <=10). Disease-Modifying Antirheumatic Drugs (DMARDs) should be initiated immediately upon diagnosis to prevent irreversible joint destruction.
1. Conventional Synthetic DMARDs (csDMARDs)
Methotrexate (Anchor csDMARD):
Dose: 15 mg weekly PO/SC, rapidly titrated to 20–25 mg weekly. Subcutaneous administration improves bioavailability and reduces gastrointestinal adverse effects.
Mandatory Co-Prescription: Folic Acid 1 mg daily (or 5 mg weekly) to mitigate mucosal ulcers, nausea, alopecia, and hematologic toxicity without diminishing efficacy.
Mechanism: Inhibits dihydrofolate reductase and aminoimidazole carboxamide ribonucleotide (AICAR) transformylase, leading to extracellular adenosine accumulation and anti-inflammatory signaling.
Monitoring: Baseline CBC, LFTs, serum creatinine, viral hepatitis serologies, and chest radiograph. Repeat CBC and LFTs every 8 to 12 weeks.
Contraindications: Pregnancy ( absolute teratogen; must stop >=3 months prior to conception in women and men ), severe renal impairment (eGFR <30 mL/min/1.73m2), chronic liver disease / cirrhosis, heavy alcohol consumption, active pulmonary fibrosis / preexisting severe lung disease.
Key Toxicities: Hepatotoxicity (transaminitis, hepatic fibrosis), myelosuppression (leukopenia, megaloblastic anemia, thrombocytopenia), oral stomatitis/aphthous ulcers, acute hypersensitivity pneumonitis (dry cough, fever, dyspnea, bilateral infiltrates; requires immediate drug discontinuation and high-dose steroids).
Hydroxychloroquine (Plaquenil):
Dose: 200–400 mg daily (maximum safe dose <= 5.0 mg/kg actual body weight/day ).
Clinical Role: Used as monotherapy in mild, non-erosive seronegative RA, or as part of "triple therapy" (Methotrexate + Sulfasalazine + Hydroxychloroquine). Safe in pregnancy.
Toxicity & Screening: Retinal toxicity (bull's-eye maculopathy) resulting in irreversible central visual field loss. Baseline ophthalmologic evaluation (fundoscopy, visual fields 10-2, spectral-domain OCT) within the first year of therapy, followed by annual screening starting after 5 years of use (or earlier in high-risk patients with renal impairment, tamoxifen use, or concurrent retinal disease).
Sulfasalazine:
Dose: 1,000 mg PO BID (titrated from 500 mg daily).
Mechanism: Cleaved by colonic bacteria into 5-aminosalicylic acid (5-ASA) and sulfapyridine.
Toxicity: Hemolytic anemia (screen for G6PD deficiency prior to initiation), leukopenia, agranulocytosis, reversible oligospermia in men, transaminitis, hypersensitivity rash.
Leflunomide (Arava):
Dose: 10–20 mg PO daily (loading dose 100 mg daily x 3 days is generally avoided due to GI intolerance).
Mechanism: Inhibits dihydroorotate dehydrogenase (DHODH) , blocking de novo pyrimidine synthesis in rapidly proliferating T and B lymphocytes.
Toxicity & Elimination: Hepatotoxicity, hypertension, peripheral neuropathy, diarrhea, teratogenicity. Enterohepatic recirculation confers an extremely long elimination half-life (~2 years). For planned pregnancy or severe toxicity, execute an accelerated drug elimination procedure with Cholestyramine 8 g PO TID for 11 days , verifying plasma leflunomide metabolite levels <0.02 mg/L on two occasions 14 days apart.
2. Biologic DMARDs (bDMARDs)
Biologic DMARDs are indicated when disease activity remains moderate-to-high despite maximally tolerated methotrexate or in patients with poor prognostic markers (high anti-CCP/RF titers, early marginal erosions).
Biologic Class Generic Name (Brand) Mechanism of Action Specific Indications & High-Yield Pearls
Anti-TNF Agents Adalimumab (Humira); Infliximab (Remicade); Etanercept (Enbrel); Golimumab (Simponi); Certolizumab pegol (Cimzia) Infliximab/Adalimumab/Golimumab: Monoclonal anti-TNF IgG.; Etanercept: Recombinant TNF receptor-Fc fusion protein.; Certolizumab: Pegylated Fab fragment (no Fc portion -> does not cross placenta; preferred anti-TNF in pregnancy ). Pre-Treatment Screening: MANDATORY screening for Latent Tuberculosis (IGRA / TST) and Hepatitis B Virus (HBsAg, anti-HBc) .; Contraindications: Active serious infections, NYHA Class III or IV Congestive Heart Failure (worsens mortality), Demyelinating Disease / Multiple Sclerosis , active malignancy.
IL-6 Receptor Antagonists Tocilizumab (Actemra); Sarilumab (Kevzara) Recombinant humanized anti-IL-6 receptor monoclonal antibody. Highly effective as monotherapy. Markedly suppresses CRP (CRP cannot be used to monitor infection). Toxicities: Hyperlipidemia, elevated transaminases, neutropenia, gastrointestinal perforation (use with extreme caution in patients with a history of diverticulitis).
T-Cell Costimulation Inhibitor Abatacept (Orencia) Soluble CTLA-4-Ig fusion protein that binds to CD80 and CD86 on antigen-presenting cells, blocking CD28 costimulation of T cells. Excellent safety profile in older adults; lowest risk of serious infections among biologics. Screen for latent TB prior to use.
Anti-CD20 Monoclonal Antibody Rituximab (Rituxan) Chimeric monoclonal antibody targeting CD20 on pre-B and mature B lymphocytes, causing B-cell lysis. Indicated in seropositive (RF+/CCP+) RA refractory to anti-TNF, and in RA complicated by rheumatoid vasculitis or Felty syndrome. High risk of Hepatitis B reactivation (fulminant hepatic necrosis); mandatory pre-treatment screening. Rare risk of Progressive Multifocal Leukoencephalopathy (PML).
3. Targeted Synthetic DMARDs (tsDMARDs) — JAK Inhibitors
Agents: Tofacitinib (Xeljanz, JAK1/JAK3 inhibitor), Baricitinib (Olumiant, JAK1/JAK2 inhibitor), Upadacitinib (Rinvoq, selective JAK1 inhibitor).
Oral Route: Potent oral small molecules targeting the Janus Kinase - Signal Transducer and Activator of Transcription (JAK-STAT) intracellular pathway.
ORAL Surveillance Trial & FDA Black Box Warnings:
Major Adverse Cardiovascular Events (MACE): Non-fatal MI, stroke, and cardiovascular death.
Venous Thromboembolism (VTE): Deep vein thrombosis and pulmonary embolism.
Malignancy: Non-melanoma skin cancer and lymphoma.
Serious Infections: Opportunistic fungal infections, reactivation of Herpes Zoster (mandates recombinant zoster vaccination [Shingrix] before starting), and reactivation of latent tuberculosis.
Guideline Rule: Reserve JAK inhibitors for patients who have had an inadequate response or intolerance to one or more anti-TNF biologics, particularly in patients >=50 years with cardiovascular risk factors or active tobacco use.
2. Seronegative Spondyloarthropathies (SpA)
The seronegative spondyloarthropathies share common genetic, clinical, and radiographic hallmarks:
HLA-B27 Genetic Association: Strongest in Ankylosing Spondylitis (90-95%), followed by Reactive Arthritis (70%), Psoriatic Arthritis (50%), and Enteropathic Arthritis (50%).
Seronegativity: Absence of Rheumatoid Factor and Anti-CCP antibodies.
Axial & Asymmetric Peripheral Joint Disease: Sacroiliitis, spondylitis, and asymmetric oligoarthritis (<5 joints, often large lower extremity joints).
Enthesitis: Inflammation at the insertion sites of tendons, ligaments, or joint capsules into bone (most commonly Achilles tendonitis and plantar fasciitis at the calcaneus).
Dactylitis ("Sausage Digits"): Uniform diffuse swelling of an entire digit due to simultaneous flexor tenosynovitis and joint synovitis.
Extra-articular Inflammation: Acute unilateral anterior uveitis (iritis) , aortic root dilation with aortic regurgitation, apical pulmonary fibrosis, and inflammatory bowel disease.
Comparison of Spondyloarthropathy Subtypes
Disease Subtype Target Demographics & Clinical Presentation Key Physical & Radiographic Findings Extra-Skeletal Manifestations First-Line & Targeted Management
Ankylosing Spondylitis (Axial SpA) Young males (age 15–40, M:F 3:1). Insidious inflammatory back pain (>3 months duration, onset <45 years, morning stiffness >30 min, improves with exercise, worsens with rest/inactivity , wakes patient in second half of night). Reduced lumbar spine flexion (modified Schober test <5 cm increase); reduced chest expansion (<2.5 cm) . Pelvic X-ray/MRI: Bilateral symmetric sacroiliitis , squaring of vertebral bodies, marginal syndesmophytes (vertical bony bridges), leading to "bamboo spine" . Acute unilateral anterior uveitis (25-30%), ascending aortic root dilation / aortic valve regurgitation , conduction abnormalities (AV block), apical pulmonary fibrocystic disease , secondary amyloidosis (AA). First-line: Continuous full-dose NSAIDs (Naproxen 500 mg BID, Celecoxib 200 mg BID, Indomethacin).; Second-line (axial disease): Anti-TNF biologics (Infliximab, Adalimumab, Etanercept) or Anti-IL-17 inhibitors (Secukinumab, Ixekizumab). (Note: Methotrexate is INEFFECTIVE for axial spine disease) .
Psoriatic Arthritis (PsA) Equal sex distribution (age 30–50). Arthritis develops in ~30% of patients with plaque psoriasis (skin lesions precede arthritis in 85%, but arthritis can precede skin disease). DIP joint involvement (classic hallmark), dactylitis , asymmetric oligoarthritis, arthritis mutilans (telescoping "opera-glass" digits). Nail changes: pitting, onycholysis, subungual hyperkeratosis (strongly correlates with DIP arthritis). X-ray: "Pencil-in-cup" deformity (erosion of proximal phalanx head with widening of distal base). Plaque psoriasis, uveitis, metabolic syndrome, accelerated cardiovascular disease. Mild: NSAIDs.; Peripheral polyarthritis: Methotrexate, Leflunomide.; Moderate-to-Severe / Axial / Refractory: Anti-TNF, Anti-IL-17 (Secukinumab, Ixekizumab), Anti-IL-23 (Guselkumab, Risankizumab), Anti-IL-12/23 (Ustekinumab), or JAK inhibitors (Upadacitinib, Tofacitinib). (Avoid systemic glucocorticoids: taper can precipitate life-threatening generalized pustular psoriasis) .
Reactive Arthritis (Reiter Syndrome) Young adults (age 20–40, M>F). Classic triad: Oligoarthritis , Urethritis / Cervicitis , and Conjunctivitis / Uveitis ("Can't see, can't pee, can't climb a tree"). Develops 1–4 weeks following a primary urogenital or enteric mucosal infection. Asymmetric oligoarthritis targeting knees and ankles; severe dactylitis and Achilles enthesitis. Pelvic X-ray: Asymmetric sacroiliitis and bulky, non-marginal, asymmetric syndesmophytes. Keratoderma blennorrhagicum (hyperkeratotic pustular/papular scaling plaques on palms and soles); Circinate balanitis (painless shallow erosions on the glans penis); sterile urethritis, stomatitis. First-line: High-dose NSAIDs.; Second-line: Intra-articular glucocorticoids, Sulfasalazine, or Methotrexate.; Antimicrobial Rule: If active Chlamydia trachomatis infection is documented, treat patient and partner with Doxycycline; antibiotics do NOT alter or cure the post-infectious arthritis once established .
Enteropathic Arthritis Occurs in 15–20% of patients with Crohn Disease or Ulcerative Colitis . Type 1 (Pauciarticular): <5 joints, asymmetric, acute onset; parallels the inflammatory activity/relapses of the underlying bowel disease .; Type 2 (Polyarticular): >=5 joints, symmetric, MCP/PIP involvement; runs an independent course from bowel flares .; Axial Spondylitis: Bilateral sacroiliitis; completely independent of bowel disease activity. Erythema nodosum, pyoderma gangrenosum, aphthous stomatitis, anterior uveitis. Treat underlying IBD. Use Anti-TNF monoclonal antibodies (Infliximab, Adalimumab) which treat both bowel and joint disease. (Avoid NSAIDs if possible, as they can trigger IBD flares; Etanercept is ineffective for Crohn disease) .