Study guide
12.4 Nodules, Tumors & Cutaneous Oncology
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
12.4 Nodules, Tumors & Cutaneous Oncology
Key Takeaways Explain This Topic AI
Seborrheic keratosis, actinic keratosis, warts, squamous cell carcinoma, basal cell carcinoma, melanoma and nevi, and mycosis fungoides are enumerated under nodules and tumors of the skin.
Full-thickness excisional biopsy with narrow margins is preferred for suspected melanoma because depth of invasion determines staging and treatment.
Shave biopsy of a suspected melanoma may transect the lesion and compromise measurement of Breslow depth.
Actinic keratoses are precursors to squamous cell carcinoma and are treated with cryotherapy or field therapy.
Mycosis fungoides is a cutaneous T-cell lymphoma that mimics eczema or psoriasis for years before diagnosis.
Last updated: August 2026
Cutaneous malignancies and severe cutaneous adverse reactions (SCAR) represent critical clinical scenarios where rapid recognition, precise histologic staging, and multidisciplinary emergency interventions dictate patient survival.
- 1. Cutaneous Oncology
- Cutaneous Melanoma
Epidemiology & Major Risk Factors: Fair skin phototype (Fitzpatrick I-II: easily burns, rarely tans), red/blond hair, blue eyes, intermittent intense UV radiation (blistering childhood sunburns), indoor tanning bed use, elevated total nevus count (>50-100 typical nevi), presence of multiple dysplastic (atypical) nevi, family or personal history of melanoma, germline mutations in CDKN2A (p16/INK4a) or CDK4 , and chronic immunosuppression.
Clinical ABCDE Diagnostic Framework:
A — Asymmetry: One half of the lesion does not mirror the other half along either axis.
B — Border Irregularity: Edges are notched, scalloped, ragged, jagged, or poorly defined.
C — Color Variation: Non-uniform pigmentation with variegated shades of brown, black, tan, blue/gray, red, or white (hypopigmented areas indicating spontaneous regression).
D — Diameter: Classically >= 6 mm (approximate diameter of a pencil eraser); however, many early melanomas are detected at <6 mm.
E — Evolving: Any change in size, shape, surface contour, color, or the onset of new symptoms (pruritus, tenderness, bleeding, crusting) over time. This is the single most sensitive clinical indicator of malignancy.
"Ugly Duckling" Sign: A melanocytic lesion that looks morphologically disparate (outlier in color, size, or shape) from all other background nevi in a given patient.
Definitive Biopsy Technique (Critical Board Rule):
Complete Full-Thickness Excisional Biopsy with narrow 1 to 3 mm normal margins extending into the subcutaneous fat (via elliptical excision, punch excision, or deep saucerization/scoop shave that encompasses the entire base of the lesion).
Strictly Contraindicated: Superficial shave biopsy, cryosurgery, laser ablation, or electrocautery. Transecting the base of a primary melanoma destroys the ability to measure Breslow depth , compromising TNM staging, prognostic stratification, and surgical margin determination.
Microscopic Prognostic Factors & Staging:
Breslow Tumor Thickness: The single most powerful prognostic indicator for primary localized melanoma. Measured in millimeters from the top of the epidermal granular layer (or base of ulcer) to the deepest invasive malignant melanocyte in the dermis/subcutis.
Ulceration: Presence of histologic ulceration upstages the T-category (e.g., T1b vs T1a) and significantly worsens prognosis.
Mitotic Rate: Number of mitoses per mm2; elevated mitotic rate indicates aggressive biology.
Sentinel Lymph Node Biopsy (SLNB): Recommended for clinical Stage I/II melanoma with: (1) Breslow thickness >= 0.8 mm (T1b-T4) ; OR (2) Breslow thickness < 0.8 mm WITH histologic ulceration (T1b) . (SLNB is not recommended for T1a [<0.8 mm non-ulcerated] due to <5% nodal positivity).
Definitive Wide Local Surgical Margins:
- Melanoma Stage / Depth Breslow Thickness Recommended Surgical Margins (to deep fascia)
- Melanoma in Situ (MIS) Intraepidermal (0.0 mm) 0.5 cm to 1.0 cm
- T1 Melanoma <= 1.00 mm 1.0 cm
- T2 Melanoma 1.01 to 2.00 mm 1.0 cm to 2.0 cm
- T3 Melanoma 2.01 to 4.00 mm 2.0 cm
- T4 Melanoma > 4.00 mm 2.0 cm
Targeted Therapy & Checkpoint Immunotherapy:
BRAF V600E / V600K Mutation: Present in ~50% of cutaneous melanomas. Mandates reflex molecular testing in Stage III/IV disease.
Combined BRAF + MEK Inhibitors: Produces rapid objective response rates (>65-75%): Dabrafenib + Trametinib , Encorafenib + Binimetinib , or Vemurafenib + Cobimetinib .
Immune Checkpoint Inhibitors (First-Line Standard for Advanced/Metastatic Disease):
Anti-PD-1 Monoclonal Antibodies: Pembrolizumab or Nivolumab (monotherapy in adjuvant Stage IIB/IIC/III or first-line metastatic).
Combination Dual Checkpoint Blockade: Nivolumab + Ipilimumab (anti-CTLA-4) provides highest median overall survival (CheckMate 067 trial) but carries high rates (~55%) of severe Grade 3-4 immune-related adverse events (irAEs: colitis, hypophysitis, hepatitis, thyroiditis, pneumonitis).
Novel Combinations: Nivolumab + Relatlimab (anti-LAG-3) (Opdualag; superior progression-free survival compared to nivolumab monotherapy with lower toxicity than ipilimumab/nivolumab).
- Non-Melanoma Skin Cancers (NMSC)
- Basal Cell Carcinoma (BCC)
Epidemiology: The most common human malignancy worldwide (>80% of all skin cancers). Arises from non-keratinizing basal cells of the interfollicular epidermis and hair follicles. Characterized by slow local invasion and tissue destruction ("rodent ulcer"); metastasis is extraordinarily rare (<0.1%) .
Clinical Subtypes & Features:
Nodular BCC (~60-70%): Classic pearly pink or translucent dome-shaped papule/nodule with rolled borders, central depression/ulceration, and fine, branching arborizing telangiectasias .
Superficial BCC (~15-20%): Erythematous, thin scaly plaque with a fine, thread-like pearly rolled border, common on trunk and extremities.
Morpheaform / Infiltrative BCC: Indurated, sclerotic, scar-like white/yellow plaque with poorly defined clinical margins; highly aggressive with extensive subclinical microscopic extension.
Management Modalities:
Standard Surgical Excision (4-5 mm margins): First-line for low-risk nodular/superficial lesions on trunk and extremities.
Electrodessication & Curettage (ED&C): Suitable only for small, low-risk superficial/nodular BCCs on non-facial sites.
Topical Therapy: Imiquimod 5% cream or 5-Fluorouracil (5-FU) 5% cream for superficial BCCs in non-critical areas.
Mohs Micrographic Surgery (MMS): Precise, tissue-sparing surgical technique involving immediate 100% intraoperative frozen-section peripheral and deep margin examination. Definitive indications for Mohs:
High-Risk Anatomical Locations ("H-Zone" of Face): Nose, periorbital/eyelids, lips, ears, chin, temples, scalp, hands, feet, and genitalia.
Aggressive Histological Subtypes: Morpheaform, infiltrative, micronodular, sclerosing, or perineural invasion.
Recurrent or Incompletely Excised Tumors .
Large Tumors: >2 cm on trunk/extremities, >1 cm on cheeks/forehead/neck, or >0.5 cm in high-risk zones.
Targeted Systemic Therapy for Locally Advanced / Metastatic BCC: Hedgehog Pathway Inhibitors ( Vismodegib or Sonidegib ) which bind to and inhibit the Smoothened ( SMO ) receptor, blocking downstream GLI1 oncogenic signaling. Adverse effects: severe muscle spasms, dysgeusia (taste loss), alopecia, and weight loss. Anti-PD-1 antibody Cemiplimab is second-line.
Squamous Cell Carcinoma (SCC) & Precursor Lesions
Epidemiology: Second most common skin cancer (~20% of NMSC). Arises from malignant epidermal keratinocytes. Carries significant metastatic potential (overall ~2-5%, but >10-30% for high-risk lesions).
Precursor Lesion — Actinic Keratosis (AK):
Rough, gritty, scaly erythematous macule or papule on chronically sun-damaged skin (face, balding scalp, ears, dorsal hands) with a characteristic "sandpaper-like" rough texture on palpation .
Pathology: Atypical keratinocytes confined to the lower epidermis (dysplasia). May progress to invasive cutaneous SCC (~0.1-1% per lesion per year; however, 60-80% of SCCs arise in actinic fields).
Treatment: Isolated lesions: Liquid nitrogen cryotherapy . Field cancerization (multiple lesions across sun-damaged field): Topical 5-Fluorouracil (5-FU) 5% cream BID for 2-4 weeks (inhibits thymidylate synthase; causes robust erythema/crusting), Topical Imiquimod 5% cream (TLR-7 agonist), Topical Tirbanibulin 1% ointment (5-day course), or Photodynamic Therapy (PDT) .
Clinical Presentation of Invasive SCC: Indurated, firm, hyperkeratotic, erythematous nodule or plaque with thick adherent scale, central crusting, ulceration, or cutaneous horn.
High-Risk Features for SCC Recurrence & Metastasis:
Anatomical site: Vermilion border of the lower lip, external ear/pinna, temple, and perineum/genitals .
Host factors: Solid organ transplant recipients (SOTRs) on chronic immunosuppression (65 to 100-fold higher incidence of SCC than general population; highly aggressive). Consider switching calcineurin inhibitors (tacrolimus) to mTOR inhibitors ( Sirolimus ). Chronic non-healing scars / burn wounds ( Marjolin's Ulcer ; carries >30% metastatic rate).
Tumor depth & histology: Thickness >4 mm, Clark level IV/V, perineural invasion (>=0.1 mm), poorly differentiated.
Management: Low-risk: Surgical excision (4-6 mm margins) or ED&C. High-risk / facial / transplant patients: Mohs Micrographic Surgery . Advanced / Metastatic SCC: Anti-PD-1 immunotherapy ( Cemiplimab or Pembrolizumab ; achieves ~50% objective response rate).
Keratoacanthoma & Cutaneous T-Cell Lymphoma (CTCL)
Keratoacanthoma (KA): Rapidly enlarging, dome-shaped erythematous nodule with a distinctive central, smooth, crateriform keratin plug that evolves over weeks. Biologically and histologically treated as a variant of well-differentiated invasive Squamous Cell Carcinoma; standard management is complete surgical excision .
Cutaneous T-Cell Lymphoma (Mycosis Fungoides & Sézary Syndrome):
Mycosis Fungoides (MF): Indolent clonal proliferation of skin-homing CD4+ memory T lymphocytes . Presents as chronic, pruritic, scaly erythematous patches and plaques in a "bathing-suit" distribution (buttocks, lower abdomen, inner thighs) that slowly progress to cutaneous tumors. Histopathology reveals epidermotropism of atypical lymphocytes with hyperconvoluted cerebriform nuclei forming intraepidermal clusters ( Pautrier microabscesses ). Early-stage therapy: Topical steroids, topical mechlorethamine (nitrogen mustard gel), phototherapy (NB-UVB / PUVA). Advanced-stage: Brentuximab vedotin (anti-CD30), Mogamulizumab (anti-CCR4), oral Bexarotene.
Sézary Syndrome: Aggressive leukemic variant of CTCL defined by the triad of: (1) Generalized pruritic erythroderma (>80% BSA) ; (2) Generalized lymphadenopathy; (3) Circulating malignant T cells with cerebriform nuclei ( Sézary cells >= 1000/mcL or CD4/CD8 ratio >= 10).