65.2 Chronic Plaque Psoriasis & Biologic Therapies

ABFM Family Medicine Certification Study Guide Exam

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1 Chapter 1: Exam Structure, Blueprint & Clinical Decision-Making

1.1 Exam Blueprint, FMCLA vs. One-Day Exam & Board Scoring 1.2 Clinical Reasoning, Test-Taking Strategy & Ambiguity Management 1.3 Evidence-Based Medicine & Clinical Practice Guidelines in Primary Care

2 Chapter 2: Healthcare Systems, Practice Management & Quality

2.1 Practice Management, Billing, Coding & Documentation 2.2 Quality Improvement, Patient Safety & Diagnostic Stewardship 2.3 Interprofessional Team-Based Care & Care Coordination

3 Chapter 3: Ethics, Law, Biostatistics & Health Equity

3.1 Medical Ethics, Informed Consent & Surrogate Decision-Making 3.2 Biostatistics, Clinical Epidemiology & Diagnostic Test Interpretation 3.3 Social Determinants of Health, Health Equity & Cultural Humility 3.4 Physician Wellness, Burnout Prevention & Professionalism

4 Chapter 4: Lifestyle Counseling & Behavior Change

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5 Chapter 5: Nutrition, Physical Activity & Chronic Disease Prevention

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6 Chapter 6: Routine Adult Immunizations

6.1 ACIP Adult Respiratory Vaccines: Influenza, COVID-19, RSV & Pneumococcal 6.2 ACIP Adult Non-Respiratory Vaccines: Tdap, Shingrix, HPV & Hep B 6.3 Immunizations in Special Populations: Pregnancy, Asplenia & Immunocompromise

7 Chapter 7: Pediatric Health Maintenance & Surveillance

7.1 Newborn Examination & Early Postnatal Care 7.2 Well-Child Care, Developmental Surveillance & Milestones 7.3 Pediatric & Adolescent Screening: Vision, Hearing, Anemia & Lead 7.4 Pediatric Oral Health, Dental Screening & Fluoride

8 Chapter 8: Behavioral Health & Safety Screening

8.1 Primary Care Depression, Anxiety & Behavioral Health Screening 8.2 Domestic Violence, Intimate Partner Violence & Firearm Safety 8.3 Occupational Health & Recreational Safety Counseling

9 Chapter 9: Adult Preventive Screening: Cardiovascular & Metabolic

9.1 Cardiovascular Disease & Hypertension Screening 9.2 Type 2 Diabetes Screening & Prediabetes Risk Stratification 9.3 Abdominal Aortic Aneurysm & Osteoporosis Screening

10 Chapter 10: Adult Cancer Screening: Breast & Gynecologic

10.1 Breast Cancer Screening & Risk-Assessment 10.2 Cervical Cancer Screening & ASCCP Algorithms 10.3 Skin Cancer Clinical Assessment & Counseling

11 Chapter 11: Adult Cancer Screening: Colorectal, Lung & Prostate

11.1 Colorectal Cancer Screening Modalities & Intervals 11.2 Lung Cancer Screening with Low-Dose CT 11.3 Prostate Cancer Screening & Shared Decision-Making

12 Chapter 12: Sexual Health, Infectious Disease Screening & Contraception

12.1 Sexual Health Counseling & Risk-Reduction Strategies 12.2 STI Screening: Chlamydia, Gonorrhea, Syphilis & Trichomoniasis 12.3 Bloodborne Infectious Disease Screening: HIV & Hepatitis C

13 Chapter 13: Reproductive Life Planning, Lactation & Preoperative Care

13.1 Preconception Planning & Comprehensive Contraception Management 13.2 Lactation Support & Breastfeeding Counseling 13.3 Preoperative Medical Evaluation & Pre-Participation Sports Exam

14 Chapter 14: Emergent Cardiovascular Conditions

14.1 Acute Coronary Syndromes & Myocardial Infarction 14.2 Acute Chest Pain Risk Stratification & Triage 14.3 Acute or Critical Valvular Heart Emergencies

15 Chapter 15: Cardiac Arrhythmias, Heart Failure & Hypertensive Crises

15.1 Acute Atrial & Ventricular Arrhythmias 15.2 Acute Decompensated Heart Failure & Cardiogenic Shock 15.3 Hypertensive Emergency & Urgency Management

16 Chapter 16: Vascular & Thromboembolic Emergencies

16.1 Pulmonary Embolism & Deep Vein Thrombosis 16.2 Acute Aortic Syndromes & Peripheral Vascular Emergencies 16.3 Critical Limb Ischemia & Acute Arterial Occlusion

17 Chapter 17: Neurologic Emergencies: Stroke & Altered Consciousness

17.1 Acute Ischemic Stroke & Intracranial Hemorrhage 17.2 Syncope Evaluation & Status Epilepticus 17.3 Acute Delirium, Encephalopathy & Severe Confusion

18 Chapter 18: Neurologic Trauma & Acute Cranial Emergencies

18.1 Concussion, Moderate-to-Severe TBI & Intracranial Injury 18.2 Thunderclap & Acute Severe Secondary Headaches 18.3 Acute Ophthalmologic Emergencies

19 Chapter 19: Acute Abdominal, Pelvic & Gastrointestinal Emergencies

19.1 Acute Abdominal & Pelvic Pain Triage 19.2 Upper & Lower Gastrointestinal Bleeding 19.3 Acute Hepatic Failure, Cholangitis & Severe Jaundice

20 Chapter 20: Acute Pulmonary & Airway Emergencies

20.1 Acute Hypoxic Respiratory Failure & ARDS 20.2 Severe Community-Acquired Pneumonia & Empyema 20.3 Acute Severe Epistaxis & Airway Obstruction

21 Chapter 21: Acute Traumatic Injuries & Wound Care

21.1 Major Trauma Resuscitation & Initial Assessment 21.2 Burn Assessment, Inhalation Injury & Resuscitation 21.3 Laceration Management, Complex Wounds & Animal Bites

22 Chapter 22: Acute Orthopedic & Musculoskeletal Emergencies

22.1 Acute Ambulatory Fractures & Initial Splinting 22.2 Compartment Syndrome & Major Orthopedic Trauma 22.3 Septic Arthritis & Acute Microcrystalline Crises

23 Chapter 23: Severe Infections, Sepsis & Systemic Emergencies

23.1 Sepsis, Septic Shock & Initial Fluid Resuscitation 23.2 Necrotizing Soft Tissue Infections & Severe CNS Infections 23.3 Anaphylaxis Diagnosis, Epinephrine Dosing & Airway Protection

24 Chapter 24: Metabolic, Endocrine & Electrolyte Emergencies

24.1 Diabetic Ketoacidosis & Hyperosmolar Hyperglycemic State 24.2 Critical Electrolyte Emergencies: Dyskalemias & Dysnatremias 24.3 Severe Calcium Abnormalities & Acute Adrenal Crisis

25 Chapter 25: Hematologic, Urologic & Dental Emergencies

25.1 Severe Symptomatic Anemias & Coagulopathic Emergencies 25.2 Testicular Torsion, Priapism & Acute Urinary Retention 25.3 Urgent Odontogenic Infections & Dental Trauma

26 Chapter 26: Psychiatric, Behavioral & Obstetric/Gynecologic Emergencies

26.1 Suicidal Ideation, Acute Agitation & Behavioral Emergencies 26.2 Acute Physical & Sexual Assault Care 26.3 Life-Threatening Vaginal Bleeding & Ectopic Pregnancy 26.4 Environmental Heat Stroke & Severe Hypothermia

27 Chapter 27: Acute Head, Neck & Neurologic Symptoms

27.1 Primary Acute Headaches: Migraine, Tension & Cluster 27.2 Concussion & Minor Closed Head Injury Evaluation 27.3 Transient Ischemic Attack Evaluation & ABCD2 Risk Scoring

28 Chapter 28: Acute Cranial Nerves, Hearing & Sensory Symptoms

28.1 Peripheral Neuropathies: Bell's Palsy, Carpal Tunnel & Radiculopathy 28.2 Acute Tinnitus, Sudden Sensorineural Hearing Loss & Cerumen Impaction 28.3 Acute Dizziness, Benign Paroxysmal Positional Vertigo & Vestibular Neuritis

29 Chapter 29: Acute Upper Respiratory Tract Infections

29.1 Acute Viral Rhinosinusitis vs. Bacterial Rhinosinusitis 29.2 Acute Pharyngitis: Group A Streptococcus & Centor Criteria 29.3 Acute Otitis Media, Otitis Externa & Serous Effusion

30 Chapter 30: Acute Lower Respiratory Infections & Cough

30.1 Influenza, COVID-19 & Viral Respiratory Syndromes 30.2 Acute Bronchitis & Lower Respiratory Tract Infections 30.3 Ambulatory Community-Acquired Pneumonia

31 Chapter 31: Allergic, Nasal & Non-Infectious Pulmonary Conditions

31.1 Allergic Rhinitis & Acute Non-Anaphylactic Allergic Reactions 31.2 Acute Dyspnea in Ambulatory Care 31.3 Interstitial Lung Diseases & Sarcoidosis Presentation

32 Chapter 32: Acute Chest, Cardiac & Vascular Symptoms

32.1 Palpitations Evaluation & Arrhythmia Triage in Primary Care 32.2 Deep Vein Thrombosis & Superficial Thrombophlebitis 32.3 Ambulatory Hypotension & Orthostasis Evaluation

33 Chapter 33: Acute Upper Gastrointestinal Conditions

33.1 Peptic Ulcer Disease & Gastritis 33.2 Dysphagia, Esophagitis & Acute Esophageal Disorders 33.3 Acute Nausea, Vomiting & Foodborne Illness

34 Chapter 34: Acute Lower Gastrointestinal Conditions

34.1 Acute Infectious Diarrhea & Gastroenteritis 34.2 Acute Constipation & Functional Bowel Changes 34.3 Ano-Rectal Disorders: Hemorrhoids, Fissures, Abscesses & Pruritus Ani

35 Chapter 35: Inflammatory, Functional & Malabsorptive GI Disorders

35.1 Acute Flares of Inflammatory Bowel Disease 35.2 Irritable Bowel Syndrome: Diagnosis, Subtyping & Management 35.3 Celiac Disease & Malabsorption Syndromes

36 Chapter 36: Acute Abdominal, Hepatic & Biliary Disorders

36.1 Ambulatory Abdominal & Pelvic Pain Triage 36.2 Acute Cholecystitis, Biliary Colic & Pancreatitis 36.3 Acute Liver Injury & Viral Hepatitis

37 Chapter 37: Acute Abdominal Wall, Hernias & Dental Conditions

37.1 Abdominal Wall, Inguinal & Ventral Hernias 37.2 Acute Dental Pain, Odontogenic Abscess & Aphthous Ulcers 37.3 Acute Edema: Unilateral vs. Bilateral Diagnostic Evaluation

38 Chapter 38: Acute Infectious Dermatoses

38.1 Bacterial Skin Infections: Impetigo, Cellulitis & Cutaneous Abscesses 38.2 Fungal Skin Infections: Tinea Corporis, Cruris, Pedis & Onychomycosis 38.3 Viral Cutaneous Infections: Herpes Simplex, Zoster & Molluscum Contagiosum

39 Chapter 39: Inflammatory, Allergic & Autoimmune Dermatoses

39.1 Atopic Dermatitis, Contact Dermatitis & Eczematous Flares 39.2 Non-Infectious Rashes: Urticaria, Drug Eruptions & Erythema Multiforme 39.3 Cutaneous Malignancies & Premalignant Lesions: AK, BCC, SCC & Melanoma

40 Chapter 40: Acute Shoulder, Elbow & Upper Extremity Injuries

40.1 Rotator Cuff Pathology, Tendinopathy & Shoulder Impingement 40.2 Lateral & Medial Epicondylitis, Olecranon Bursitis & Elbow Sprains 40.3 Wrist & Hand Soft-Tissue Injuries: De Quervain, TFCC & Finger Sprains

41 Chapter 41: Acute Knee, Ankle & Lower Extremity Injuries

41.1 Meniscal Tears, Ligamentous Knee Injuries & Patellofemoral Pain 41.2 Ankle Sprains, Ottawa Ankle Rules & Achilles Tendinopathy 41.3 Plantar Fasciitis, Shin Splints & Overuse Syndromes

42 Chapter 42: Acute Ambulatory Fractures & Dislocations

42.1 Distal Radius, Scaphoid & Common Upper Extremity Fractures 42.2 Metatarsal, Clavicle & Common Lower Extremity Fractures 42.3 Joint Dislocation Management: Nursemaid's Elbow & Shoulder Subluxation

43 Chapter 43: Acute Axial Musculoskeletal Pain & Falls

43.1 Acute Low Back Pain: Red Flags, Strain & Disc Herniation 43.2 Acute Cervical Strain, Whiplash & Axial Neck Pain 43.3 Evaluation of Falls in Ambulatory & Older Patients

44 Chapter 44: Acute Inflammatory Arthropathies & Generalized Pain

44.1 Acute Inflammatory Arthritis & Spondyloarthropathies 44.2 Myalgias, Rhabdomyolysis & Post-Viral Pain Syndromes 44.3 Acute Non-Headache Pain Management Strategies

45 Chapter 45: Acute Renal, Urinary & Genitourinary Conditions

45.1 Uncomplicated UTI, Pyelonephritis & Acute Urethritis 45.2 Hematuria Workup & Glomerulonephritis 45.3 Nephrolithiasis & Acute Urinary Tract Obstruction

46 Chapter 46: Acute Male Genitourinary & Prostatic Conditions

46.1 Acute Prostatitis, Epididymitis & Orchitis 46.2 Acute Scrotal Pain: Torsion vs Appendage, BPH & Male Genital Emergencies 46.3 Acute Urinary Retention & Incontinence Evaluation

47 Chapter 47: Acute Women's Health & Early Pregnancy Care

47.1 Early Pregnancy Diagnosis, Dating & Initial Complications 47.2 Abnormal Uterine Bleeding & Acute Menstrual Disorders 47.3 Premenstrual Syndrome & Premenstrual Dysphoric Disorder

48 Chapter 48: Breast Disorders, STIs & Pediatric Elimination

48.1 Palpable Breast Mass, Mastitis & Nipple Discharge 48.2 Sexually Transmitted Infections: Diagnosis, Staging & CDC Guidelines 48.3 Pediatric Enuresis & Encopresis

49 Chapter 49: Systemic Signs, Metabolic Dysregulation & Miscellaneous Infections

49.1 Acute Fever, Sepsis Screening & FUO in Primary Care 49.2 Acute Hyperglycemia & Symptomatic Hypoglycemia 49.3 Electrolyte Abnormalities: Mild-to-Moderate Disturbances 49.4 Vector-Borne, Tick-Borne & Rickettsial Illnesses

50 Chapter 50: Chronic Cardiovascular Diseases: Hypertension & Ischemia

50.1 Essential Hypertension Management: 2025 AHA/ACC Guideline & JNC Strategies 50.2 Chronic Coronary Artery Disease & Post-MI Secondary Prevention 50.3 Chronic Heart Failure: HFrEF, HFpEF & Quadruple GDMT

51 Chapter 51: Chronic Vascular, Valvular & Dyslipidemic Diseases

51.1 Peripheral Arterial Disease & Claudication 51.2 Chronic Valvular Heart Disease & Murmur Evaluation 51.3 Lipid Disorders & ASCVD Risk-Based Statin Therapy

52 Chapter 52: Chronic Respiratory Diseases: Asthma & COPD

52.1 Chronic Asthma Management: GINA Stepwise SMART Therapy 52.2 Chronic Obstructive Pulmonary Disease: GOLD Recommendations 52.3 Solitary Pulmonary Nodule Evaluation & Fleischner Society Criteria

53 Chapter 53: Chronic Metabolic Diseases: Diabetes Mellitus

53.1 Type 2 Diabetes Management: ADA Pharmacotherapy Algorithms 53.2 Type 1 Diabetes: Basal-Bolus Insulin, CGMs & Diabetic Complications 53.3 Diabetic Microvascular & Macrovascular Disease Surveillance

54 Chapter 54: Obesity, Nutrition & Metabolic Bone Diseases

54.1 Medical & Behavioral Management of Obesity & Incretin Mimetics 54.2 Osteoporosis & Metabolic Bone Disease: DEXA, FRAX & Antiresorptives 54.3 Nutritional Deficiencies: Vitamin D, B12, Iron & Malnutrition

55 Chapter 55: Chronic Endocrine Disorders

55.1 Primary & Subclinical Hypothyroidism, Hyperthyroidism & Nodules 55.2 Adrenal Disorders: Addison's Disease & Cushing's Syndrome 55.3 Hypercalcemia, Hyperparathyroidism & Pituitary Disorders

56 Chapter 56: Chronic Kidney Disease & Venous Disorders

56.1 Chronic Kidney Disease: KDIGO Staging & Renoprotective Therapy 56.2 Chronic Venous Insufficiency, Stasis Dermatitis & Lymphedema 56.3 Chronic Electrolyte & Acid-Base Management in CKD

57 Chapter 57: Chronic Gastrointestinal & Hepatic Diseases

57.1 Gastroesophageal Reflux Disease, Barrett's Esophagus & Dyspepsia 57.2 Chronic Liver Disease: MASLD/NAFLD, Cirrhosis & Portal Hypertension 57.3 Viral Hepatitis B & C: Long-Term Monitoring & DAA Therapy

58 Chapter 58: Colorectal Surveillance & Chronic Pancreaticobiliary Care

58.1 Post-Polypectomy Colorectal Polyp Surveillance Guidelines 58.2 Chronic Pancreatitis & Exocrine Pancreatic Insufficiency 58.3 Chronic Nausea, Gastroparesis & Functional GI Disorders

59 Chapter 59: Chronic Musculoskeletal & Rheumatologic Disorders

59.1 Osteoarthritis: Hip, Knee & Hand Management 59.2 Spinal Conditions: Spinal Stenosis, Spondylolisthesis & Compression Fractures 59.3 Chronic Myopathies & Fibromyalgia Syndrome

60 Chapter 60: Chronic Neurologic & Neurodegenerative Disorders

60.1 Dementia: Alzheimer's, Vascular & Lewy Body Disease 60.2 Parkinson's Disease & Essential Tremor 60.3 Epilepsy: Chronic Antiseizure Medications & Post-Stroke Care

61 Chapter 61: Chronic Peripheral Nerves, Pain & Sensory Disorders

61.1 Diabetic & Chronic Peripheral Neuropathies 61.2 Chronic Pain Syndromes & Chronic Daily Headaches 61.3 Chronic Tinnitus, Presbycusis & Persistent Dizziness

62 Chapter 62: Chronic Psychiatric Disorders

62.1 Major Depressive Disorder & Generalized Anxiety Disorder 62.2 Bipolar Disorder: Maintenance Pharmacotherapy & Lithium Monitoring 62.3 Adult & Pediatric Attention-Deficit/Hyperactivity Disorder

63 Chapter 63: Chronic Behavioral Health & Neurodevelopmental Conditions

63.1 Chronic Behavioral Conditions: PTSD, OCD & Somatization 63.2 Autism Spectrum Disorder & Intellectual Disabilities 63.3 Eating Disorders: Anorexia Nervosa, Bulimia & Binge Eating

64 Chapter 64: Chronic Substance Use Disorders & Tobacco Cessation

64.1 Alcohol Use Disorder: Pharmacotherapy & Relapse Prevention 64.2 Opioid & Stimulant Use Disorders: MOUD & Harm Reduction 64.3 Longitudinal Tobacco Cessation Pharmacotherapy

65 Chapter 65: Chronic Dermatologic Conditions

65.1 Acne Vulgaris, Rosacea & Seborrheic Dermatitis 65.2 Chronic Plaque Psoriasis & Biologic Therapies 65.3 Chronic Eczema, Hidradenitis Suppurativa & Cutaneous Lupus

66 Chapter 66: Chronic Reproductive, Infectious & Geriatric Special Care

66.1 Chronic Menstrual Disorders, Infertility & Sexual Dysfunction 66.2 Menopause Management & Hormone Replacement Therapy 66.3 Chronic HIV Infection Management & Primary Care Integration 66.4 Gender-Affirming Primary Care & Hormone Therapy 66.5 Advance Care Planning, Palliative Care & End-of-Life Symptom Control

67 Chapter 67: Continuity Care: Sleep, Fatigue, Cancer, Pregnancy & the Adult Preventive Visit

67.1 Chronic Insomnia & Obstructive Sleep Apnea 67.2 Chronic Malaise, Fatigue & ME/CFS 67.3 Primary Care During Cancer Treatment & Survivorship 67.4 Routine Prenatal Care & Longitudinal Pregnancy Management 67.5 The Periodic Adult Health Examination & Medicare Annual Wellness Visit

65.2 Chronic Plaque Psoriasis & Biologic Therapies

Key Takeaways Explain This Topic AI

Psoriasis is an immune-mediated systemic inflammatory disease driven by the IL-23 / Th17 / IL-17 cytokine axis, which shortens epidermal keratinocyte cell turnover from 28 days to 3–5 days, producing parakeratosis and dermal vascular hyperplasia.

Chronic plaque psoriasis manifests as sharply demarcated erythematous plaques covered with silvery-white micaceous scales on extensor surfaces, displaying Auspitz sign (punctate bleeding on scale removal) and the Koebner phenomenon (lesions at sites of cutaneous trauma).

Mild-to-moderate disease (<3–5% BSA) is managed with high-potency topical corticosteroids combined synergistically with topical vitamin D3 analogues (calcipotriene); systemic oral corticosteroids (e.g., prednisone) are STRICTLY CONTRAINDICATED due to the catastrophic risk of precipitating generalized pustular psoriasis or erythroderma upon withdrawal.

Moderate-to-severe psoriasis (>5–10% BSA or psoriatic arthritis) warrants phototherapy or targeted biologic therapy: TNF-alpha inhibitors (adalimumab), IL-17 inhibitors (secukinumab; caution in inflammatory bowel disease), or IL-23 inhibitors (guselkumab, risankizumab).

Prior to initiating any biologic therapy, mandatory screening must be completed: latent tuberculosis testing (IGRA/PPD + chest radiograph), hepatitis B panel (HBsAg, anti-HBs, anti-HBc due to fatal reactivation risk), hepatitis C, and administration of indicated non-live vaccines.

Last updated: September 2026

Immunopathogenesis & Histopathology of Psoriasis

Psoriasis is a chronic, non-contagious, immune-mediated systemic inflammatory disorder with primary cutaneous and articular manifestations, affecting 2% to 3% of the global population. Far from being a localized epidermal disease, psoriasis is characterized by systemic vascular and metabolic inflammation, substantially conferring an increased risk of premature atherosclerotic cardiovascular disease, myocardial infarction, metabolic syndrome, non-alcoholic fatty liver disease (NAFLD), and depression.

The IL-23 / Th17 / IL-17 Pathogenic Axis

The pathophysiology of psoriasis is driven by dysregulated innate and adaptive immune crosstalk within the skin:

Innate Immune Activation : Cutaneous trauma, infection, or environmental stress prompts stressed keratinocytes to release antimicrobial peptides, notably LL-37 (cathelicidin) . LL-37 complexes with self-DNA or self-RNA, binding Toll-like receptors (TLR-7, TLR-8, TLR-9) on plasmacytoid dendritic cells (pDCs) , stimulating robust production of interferon-alpha (IFN-α).

Myeloid Dendritic Cell Activation & IL-23 Secretion : IFN-α activates dermal myeloid dendritic cells, which migrate to regional lymph nodes and secrete high concentrations of interleukin-23 (IL-23) and interleukin-12 (IL-12) .

T-Helper 17 (Th17) Polarization & Expansion : IL-23 binds its receptor on CD4+ T-helper 17 (Th17) cells and innate lymphoid cells, promoting their survival, proliferation, and activation.

Effector Cytokine Storm : Activated Th17 cells migrate into the skin and release potent effector cytokines: IL-17A, IL-17F, and IL-22 :

IL-17A & IL-17F : Bind receptors on epidermal keratinocytes, inducing massive transcription of chemokines (CXCL1, CXCL8) that recruit circulating neutrophils and perpetuate feed-forward inflammatory loops.

IL-22 : Acts synergistically with IL-17 to stimulate aberrant, uncontrolled keratinocyte hyperproliferation and inhibit terminal differentiation. THE IMMUNOPATHOGENIC AXIS OF PSORIASIS

Cutaneous Trauma / Stress ──► Keratinocytes release LL-37 + self-DNA/RNA
│
▼
Plasmacytoid Dendritic Cells (pDCs)
│ (Interferon-alpha [IFN-α])
▼
Dermal Myeloid Dendritic Cells
│ (Interleukin-23 [IL-23])
▼
Th17 Cell Expansion
│ (IL-17A, IL-17F, IL-22)
▼
Epidermal Keratinocyte Hyperproliferation
& Neutrophilic Recruitment (Microabscesses)
Histopathologic Hallmarks & Epidermal Kinetics

Accelerated Keratinocyte Transit : In normal epidermis, the transit time from basal layer stem cell to desquamation at the stratum corneum spans 28 days . In active psoriatic plaques, this transit is accelerated nearly tenfold to 3 to 5 days . Keratinocytes lack adequate time to mature, synthesize keratohyalin granules, or lose their nuclei.

Parakeratosis : Retention of pyknotic nuclei within the stratum corneum, accompanied by complete absence or marked thinning of the stratum granulosum (agranulosis).

Acanthosis & Rete Elongation : Marked, regular thickening of the epidermis with uniform, club-shaped elongation of the epidermal rete ridges into the dermis.

Dermal Vascular Hyperplasia : The dermal papillae exhibit marked thinning of their suprapapillary epidermal plates, accompanied by prominent tortuous, dilated, hyperpermeable capillary loops driven by vascular endothelial growth factor (VEGF).

Neutrophilic Infiltration : Neutrophils migrate into the spinous layer to form spongiform pustules of Kogoj , and into the parakeratotic stratum corneum to form Munro microabscesses .

Clinical Phenotypes & Physical Diagnostic Signs CLINICAL SUBTYPES OF PSORIASIS VULGARIS

Phenotype Clinical Morphology & Distribution Triggers & Clinical Pearls

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Chronic Plaque Sharp, raised erythematous plaques covered by Predilection for extensor surfaces (elbows,
(Psoriasis Vulgaris) thick, micaceous silvery-white scales; knees), scalp, lumbosacral region, umbilicus;

[80%–90% of cases] symmetrical distribution; pruritus variable. displays Auspitz sign and Koebner phenomenon.

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Guttate Psoriasis Sudden eruption of crops of small (0.5–1.5 cm), Classic onset 1–3 weeks following Streptococcus

discrete, drop-like salmon-pink papules on pyogenes (GAS) pharyngitis or perianal strep;

the trunk and proximal extremities. check ASO titer / throat swab; phototherapy.

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Inverse / Smooth, red, glistening, sharply demarcated Affects warm, moist body folds (axillae, groin,
Intertriginous plaques COMPLETELY LACKING SILVERY SCALE inframammary, gluteal cleft); easily misdiagnosed

(scale is macerated and sloughed by friction). as Candida (Candida has satellite pustules!).

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Pustular Psoriasis Sheets of sterile, pinhead-sized yellow pustules CLASSICALLY PRECIPITATED BY ABRUPT WITHDRAWAL

(von Zumbusch) arising on fiery, tender erythematous skin; OF SYSTEMIC ORAL CORTICOSTEROIDS! Inpatient

fever, leukocytosis, hypocalcemia, toxicity. medical emergency; high mortality.

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Erythrodermic Generalized, inflammatory erythema and scaling Compromised barrier: hypothermia, high-output
Psoriasis involving > 90% of Total Body Surface Area; cardiac failure, protein loss, sepsis; requires

life-threatening dermatologic emergency. burn-unit / ICU-level fluid resuscitation.

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Cardinal Physical Signs

Auspitz Sign : When the thick, micaceous, silvery scale of a chronic plaque is gently scraped or peeled away, tiny punctate bleeding droplets appear beneath. This bleeding occurs because the suprapapillary epidermal plates are severely thinned, leaving fragile, engorged, tortuous papillary capillary loops vulnerable to immediate rupture upon minimal mechanical friction.

Koebner Phenomenon (Isomorphic Response) : The emergence of characteristic psoriatic plaques in previously unaffected skin along the precise lines or sites of cutaneous mechanical trauma (e.g., surgical incisions, physical scratches, thermal burns, tape application, or sunburn). Typically manifests 7 to 14 days following cutaneous injury.

Psoriatic Nail Disease: Predictor of Arthritis

Nail involvement occurs in up to 50% of cutaneous psoriasis patients and in >80% of individuals with psoriatic arthritis. Anatomical location dictates morphology:

Nail Matrix Involvement : Produces nail pitting (small, thimble-like, punctate surface depressions caused by focal parakeratosis within the dorsal nail matrix) and leukonychia.

Nail Bed Involvement : Produces pathognomonic "oil-drop" or "salmon-patch" dyschromia (translucent, yellowish-red discoloration beneath the nail plate due to localized capillary pooling and exudate), subungual hyperkeratosis (accumulation of flaky scale under the free edge), splinter hemorrhages, and distal onycholysis (separation of the nail plate from the bed).

Clinical Pearl : Severe nail dystrophy is a powerful independent predictor of concurrent or impending Psoriatic Arthritis (PsA) , particularly involving the distal interphalangeal (DIP) joints, due to the close anatomical entheseal continuity between the extensor tendon, nail bed, and periosteum.

Psoriatic Arthritis (PsA) & The CASPAR Criteria

Psoriatic arthritis develops in 20% to 30% of patients with plaque psoriasis, typically arising 5 to 10 years after skin manifestations, though in 15% of cases arthritis precedes or coincides with cutaneous disease. It is a seronegative spondyloarthropathy (rheumatoid factor [RF] and anti-CCP antibodies are typically negative).

Clinical Patterns of Psoriatic Arthritis

Distal Interphalangeal (DIP) Predominant : Classic form; affects DIP joints with concurrent nail dystrophy; spared in rheumatoid arthritis.

Asymmetric Oligoarthritis : Involves fewer than 5 small or large joints (e.g., one knee, one PIP, one DIP).

Symmetric Polyarthritis : Clinically mimics rheumatoid arthritis involving MCP and PIP joints, but distinguished by negative RF and DIP involvement.

Axial Spondyloarthritis : Asymmetric sacroiliitis and spondylitis (inflammatory back pain, morning stiffness improving with activity).

Arthritis Mutilans : Severe, osteolytic, deforming joint destruction producing "telescoping" or "opera-glass" digits ( main en lorgnette ).

Diagnostic Hallmarks

Dactylitis ("Sausage Digits") : Diffuse, uniform, painful soft-tissue swelling of an entire finger or toe extending beyond the joint capsule, driven by concurrent flexor tenosynovitis, joint synovitis, and periarticular enthesitis.

Enthesitis : Severe inflammation at the anatomic insertion sites of tendons, ligaments, and fascia into bone. The most common clinical targets are the insertion of the Achilles tendon onto the calcaneus and the plantar fascia .

The CASPAR Classification Criteria (Score ≥3 indicates PsA) :

Established inflammatory articular disease (joint, spine, or entheseal) PLUS ≥3 points from:

Current psoriasis (2 points) OR Personal history of psoriasis (1 point) OR Family history of psoriasis (1 point).

Characteristic psoriatic nail dystrophy (1 point).

Negative rheumatoid factor (1 point).

Current or historical dactylitis (1 point).

Radiographic evidence of new bone formation (ill-defined ossification near joint margins, excluding osteophytes; 1 point).

Stepwise Management Ladder (AAD/NPF Guidelines)

Therapeutic selection depends on disease severity, quantified by Total Body Surface Area (BSA) involvement (using the patient's palm with closed fingers as equivalent to ~1% BSA), anatomic location, and the presence of joint disease.

Mild Disease : <3% to 5% BSA, with no involvement of sensitive sites (face, palms, soles, genitalia) and no psoriatic arthritis.

Moderate-to-Severe Disease : >5% to 10% BSA, or involvement of high-impact/sensitive sites causing severe functional/psychosocial disability, or concurrent Psoriatic Arthritis.

Step 1: Topical Therapies for Mild-to-Moderate Disease

High-Potency Topical Corticosteroids (Class 1 & 2) :

Agents: Clobetasol propionate 0.05% (Class 1 superpotent) or Betamethasone dipropionate 0.05% (Class 2 potent) ointment/cream applied twice daily.

Indication: Thick, stubborn plaques on extensor surfaces (elbows, knees, trunk).

Dosing Protocol: Applied BID for up to 2 to 4 consecutive weeks to induce clearance, followed by a transition to intermittent "pulse dosing" (e.g., weekend-only application) to prevent tachyphylaxis, epidermal atrophy, striae distensae, and hypothalamic-pituitary-adrenal (HPA) axis suppression.

Topical Vitamin D3 Analogues (Calcipotriene, Calcitriol) :

Mechanism: Bind intracellular vitamin D receptors (VDR) in keratinocytes, directly inhibiting keratinocyte proliferation, promoting normal terminal differentiation, and suppressing IL-17 and IL-22 release.

The Calcipotriene-Steroid Synergy : Combining a topical vitamin D analogue with a high-potency topical corticosteroid (available as fixed-dose combination calcipotriene 0.005%/betamethasone dipropionate 0.064% suspension, ointment, or foam) yields superior clearance rates compared to either agent alone. Crucially, calcipotriene counteracts corticosteroid-induced epidermal atrophy , while the steroid mitigates calcipotriene-induced local skin irritation.

Topical Calcineurin Inhibitors (Tacrolimus 0.1% ointment, Pimecrolimus 1% cream) & Topical PDE-4 Inhibitors (Roflumilast 0.3% cream) :

Highly effective, non-steroidal therapies specifically indicated for sensitive, skin-thinning-prone areas: facial psoriasis and intertriginous/inverse psoriasis .

Topical Tazarotene (0.05%–0.1%) : Topical retinoid; used synergistically with topical corticosteroids to reduce plaque thickness.

Step 2: Phototherapy

Narrowband Ultraviolet B (NB-UVB: 311–313 nm) : The phototherapy standard of care. Administered in outpatient light booths 2 to 3 times weekly. NB-UVB penetrates the epidermis and superficial papillary dermis, inducing apoptosis of pathogenic infiltrating T-lymphocytes, suppressing Langerhans cell antigen presentation, and stimulating anti-inflammatory cytokines (IL-10). Highly effective, cost-efficient, and exceptionally safe during pregnancy.

Psoralen + UVA (PUVA) : Combines oral methoxsalen with long-wave UVA; now rarely utilized due to a substantial cumulative, dose-dependent risk of non-melanoma skin cancer (squamous cell carcinoma) and cutaneous melanoma.

Step 3: Traditional Oral Systemic Therapies

Used for moderate-to-severe disease when phototherapy is inaccessible or inadequate:

Methotrexate (MTX) :

Dosing: 10 to 25 mg once weekly (orally or subcutaneous) + folic acid 1 mg daily (to reduce GI and hematologic toxicity).

Mechanism: Dihydrofolate reductase inhibitor; suppresses lymphocyte DNA synthesis and enhances adenosine-mediated anti-inflammatory signaling. Treats both cutaneous plaques and peripheral psoriatic arthritis.

Toxicity & Monitoring: Baseline CBC, CMP (liver transaminases, creatinine), and hepatitis serologies. Serial monitoring every 8–12 weeks. High risk of hepatotoxicity (liver fibrosis), bone marrow suppression (macrocytosis, leukopenia), and hypersensitivity pneumonitis. Strictly teratogenic (Pregnancy Category X; requires reliable contraception in men and women).

Apremilast (Otezla) :

Dosing: 30 mg orally twice daily (titrated over 5 days to reduce GI side effects).

Mechanism: Small-molecule oral phosphodiesterase-4 (PDE-4) inhibitor ; raises intracellular cyclic AMP (cAMP) levels, downregulating TNF-α, IL-23, and IL-17 while upregulating IL-10.

Advantages: Requires zero routine laboratory blood monitoring ; safe in active infections where biologics are contraindicated.

Adverse Effects: Diarrhea and nausea (usually transient during weeks 1–2), tension headaches, weight loss (screen weight), and new or worsening depression/suicidal ideation.

Cyclosporine :

Dosing: 2.5 to 5.0 mg/kg/day divided twice daily.

Mechanism: Calcineurin inhibitor; suppresses IL-2 transcription and T-cell activation. Rapid onset of action (clears disease within 2–4 weeks).

Clinical Role & Hard Rule: Reserved strictly for rapid rescue therapy in acute, catastrophic flares (e.g., severe erythrodermic or pustular psoriasis). Treatment duration must be strictly capped at <1 year due to cumulative, irreversible nephrotoxicity, malignant hypertension, and increased risk of cutaneous malignancies. Frequent monitoring of blood pressure and serum creatinine (every 2 weeks initially) is mandatory.

Step 4: Targeted Biologic Therapies (PASI-90 to PASI-100 Clearance)

Biologics are recombinant monoclonal antibodies or fusion proteins that target specific cytokines driving the immunopathogenic cascade. They achieve unprecedented clinical clearance rates (often achieving PASI-90 or PASI-100, representing 90% to 100% plaque clearance). TARGETED BIOLOGIC THERAPIES FOR MODERATE-TO-SEVERE PSORIASIS

Biologic Class Targeted Molecular Axis Specific Agents Key Indications & Clinical Warnings

TNF-alpha Inhibits soluble & • Adalimumab (Humira) First-line for severe coexisting PsA
Inhibitors membrane-bound TNF-α; • Infliximab (Remicade) (especially axial/spine involvement);
dampens broad systemic • Etanercept (Enbrel) Black box warning: Latent TB reactivation,

inflammatory cascades • Certolizumab (safe in preg) demyelinating disease (MS), worsens CHF.

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IL-17 Neutralizes IL-17A or • Secukinumab (Cosentyx) Ultra-rapid cutaneous clearance;
Inhibitors blocks IL-17 receptor • Ixekizumab (Taltz) Side effects: Mucocutaneous candidiasis;
(IL-17RA) • Brodalumab (Siliq) CRITICAL CONTRAINDICATION: INFLAMMATORY

BOWEL DISEASE (triggers Crohn / UC flares!).

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IL-23 Binds p19 subunit of IL-23 • Guselkumab (Tremfya) Exceptional long-term durability;
Inhibitors (or p40 subunit shared by • Risankizumab (Skyrizi) Infrequent dosing (every 8 to 12 weeks);
IL-12/23: Ustekinumab) • Tildrakizumab (Ilumya) Superior safety profile; does not trigger

• Ustekinumab (Stelara) candidiasis or inflammatory bowel disease.

Mandatory Pre-Biologic Screening Protocol

Prior to administering the first dose of any biologic therapy, the family physician must execute a strict, standardized pre-immunosuppression screening protocol:

Latent Tuberculosis Screening :

Interferon-Gamma Release Assay (IGRA) : QuantiFERON-TB Gold or T-SPOT (preferred over tuberculin skin test [PPD] in patients vaccinated with BCG).

Baseline Chest Radiograph : Mandatory to rule out active pulmonary tuberculosis.

Management of Positive Screen : If latent TB is diagnosed (positive IGRA without active disease on radiograph), the patient must initiate preventive chemotherapy (e.g., daily isoniazid for 9 months or rifampin daily for 4 months) for at least 1 full month prior to initiating the biologic .

Viral Hepatitis Serological Panel :

Hepatitis B : Must obtain HBsAg (surface antigen) , anti-HBs (surface antibody) , and total anti-HBc (core antibody) .

Why anti-HBc is essential : Even if HBsAg is negative, an isolated positive anti-HBc indicates past resolved infection where HBV cccDNA persists in hepatocytes. Under potent biologic immunosuppression (especially anti-TNF), HBV can fulminantly reactivate , precipitating acute liver failure and death. Prophylactic entecavir or tenofovir is required under hepatology guidance.

Hepatitis C : Anti-HCV antibody (with reflex HCV RNA if positive).

Complete Blood Count & Comprehensive Metabolic Panel : Establish baseline bone marrow reserve and hepatic/renal clearance.

Immunization Review :

All indicated age-appropriate inactivated vaccines (Pneumococcal conjugate/polysaccharide, Recombinant Zoster [Shingrix], COVID-19, annual Influenza) should ideally be completed at least 2 to 4 weeks before immunosuppressive initiation.

[!CRITICAL] Strict Prohibition of Live Vaccines on Biologics LIVE-ATTENUATED VACCINES ARE STRICTLY CONTRAINDICATED while a patient is receiving biologic therapies. These include MMR, Varicella, Yellow Fever, Oral Typhoid, and Live-Attenuated Intranasal Influenza. Live vaccines risk uninhibited viral replication, disseminated infection, and death in the immunosuppressed host.

The Cardinal Board Exam Contraindication

[!CRITICAL] Never Prescribe Systemic Oral Corticosteroids for Plaque Psoriasis Systemic oral corticosteroids (e.g., prednisone, dexamethasone, methylprednisolone "dose packs") should NEVER be administered for the treatment of chronic plaque psoriasis . While oral steroids may produce dramatic, rapid, temporary skin clearance, tapering or abruptly discontinuing the steroid triggers a catastrophic rebound phenomenon . This rebound routinely precipitates life-threatening Generalized Pustular Psoriasis of von Zumbusch or Erythrodermic Psoriasis , resulting in high-output heart failure, septic shock, hypothermia, and death. Systemic steroids have no role in psoriasis management.