Click any card to flip · 20 Step 1 high-yield concepts0 / 20 seen
LO 1 — Infectious Esophagitis: HSV
Histo finding, esophageal lesion appearance, and high-risk population?
Answer
Histo:Multinucleated giant cells (syncytial formation) at base of ulcers Lesion:Punched-out ulcers with sharp borders + base of fibrin/exudate Risk: Immunocompromised (AIDS, chemo, transplant); neutropenia Dx: PCR, culture, Tzanck smear, or biopsy with immunostain
LO 1 — Infectious Esophagitis: CMV
Histo finding, ulcer pattern, and distinguishing feature from HSV?
Answer
Histo:Owl-eye inclusions (large cells with smudged nucleus + halo) — also ground-glass nuclei Lesion:Large, linear/longitudinal ulcers (not punched-out like HSV) Distinguished from HSV: NO multinucleated cells; giant cells have solitary nucleus Risk: CD4 <50 in AIDS; post-transplant
LO 1 — Infectious Esophagitis: Candida
Visual appearance, microscopy, immune status risk, and treatment?
Answer
Appearance: White plaques/pseudomembrane (thrush); erythematous mucosa Histo: Fungal hyphae + pseudohyphae (KOH prep, PAS stain) Risk: AIDS, chemo, antibiotics (dysbiosis), corticosteroids Tx: Fluconazole (first-line) or amphotericin B if refractory
LO 2 — GERD & Metaplasia
Squamous epithelium changes; definition of Barrett's metaplasia and cell type?
Answer
Normal: Esophagus has non-keratinized stratified squamous epithelium GERD: Chronic acid reflux → mucosal injury → inflammation Barrett's: Metaplasia of squamous → intestinal epithelium with goblet cells (columnar, mucus-secreting) Definition: Intestinal metaplasia in distal esophagus (endoscopic + histo confirmation) Risk: ~0.2% annual progression to adenocarcinoma (10% lifetime)
LO 3 — SCC vs. Adenocarcinoma Location
Typical locations, risk factors for each, and which is more common?
Answer
SCC: Upper/middle third esophagus; smoking + alcohol (synergistic) Adenocarcinoma: Lower third esophagus/GE junction; Barrett's is main risk factor US trend: Adenocarcinoma now MORE common than SCC in Western countries Prognosis: Both poor (~20% 5-yr survival); late diagnosis
LO 4 — Acute Gastritis
Three main etiologies, and what are Curling vs. Cushing ulcers?
Answer
Main causes: NSAIDs, alcohol, stress Curling ulcer: Acute gastric ulcer after severe BURN injury (hypovolemia/ischemia) Cushing ulcer: Acute gastric ulcer after CNS trauma/surgery (↑gastric acid from ↑vagal tone) Histo: Mucosal edema, neutrophilic infiltration, erosion (confined to mucosa)
LO 5 — Erosion vs. Ulcer
Histologic definition of each; why this distinction matters?
Answer
Erosion: Defect confined to mucosa (superficial); mucosa only; reversible Ulcer: Defect extends through muscularis mucosae into submucosa ± muscularis; deeper; slow healing; risk of perforation Clinical impact: Ulcers bleed more (submucosal vessels), scar more (fibrosis), take weeks to heal
LO 6 — H. pylori Location & Effect
Where does H. pylori live; duodenal vs. gastric ulcer distribution; cancer risk?
Answer
Location:Antral mucosa (distal stomach); lives in protective layer Duodenal ulcer: H. pylori → ↑acid → gastric metaplasia in duodenum → ulcers Gastric ulcer: H. pylori + NSAIDs → direct mucosal damage Cancer risk: Type I gastric cancer (intestinal) — H. pylori → chronic inflammation → metaplasia/dysplasia/cancer (MAGGAD sequence)
LO 6 — Autoimmune Gastritis
Location of inflammation, which cell type destroyed, gastrin level, and main deficiency?
Answer
Location:Body/fundus of stomach (NOT antral) Destroyed: Parietal cells (antibodies to parietal cell + intrinsic factor) Result: Loss of HCl + intrinsic factor → achlorhydria Gastrin: ↑↑Elevated (no feedback inhibition from acid) Deficiency: B12 malabsorption → pernicious anemia
LO 7 — Duodenal vs. Gastric PUD
Risk factors, pain relationship to food, and complications?
Answer
Duodenal: H. pylori >> NSAIDs; pain relieved by food/antacid; hypersecretion of acid; perforation common Gastric: NSAIDs ≈ H. pylori; pain WORSE with food; hypersecretion less likely; bleeding more common Both: Can perforate, bleed, or stenose with chronic ulceration
LO 8 — PUD Healing & Treatment
How do PPIs work, triple therapy drugs, and timeline for healing?
Answer
PPIs (omeprazole): Irreversibly block H⁺/K⁺-ATPase on parietal cells → suppress acid Triple therapy: PPI + amoxicillin + clarithromycin (or PPI + bismuth + metronidazole/tetracycline) for H. pylori eradication Healing: Duodenal 4–6 weeks; gastric 8–12 weeks on PPI monotherapy
LO 9 — Precancerous Sequence
Define intestinal metaplasia, dysplasia, and atrophy; which is reversible?
Answer
Intestinal metaplasia: Glandular replacement by intestinal-type epithelium (with goblet cells); potentially reversible if H. pylori eradicated early Dysplasia: Architectural/cytologic atypia (Low-grade vs. High-grade); increased nucle-to-cytoplasm ratio; NOT reversible Atrophy: Loss of glands → thin mucosa; also not reversible Sequence: Normal → atrophy → metaplasia → dysplasia → cancer
LO 10 — Gastric Cancer: Intestinal Type
Histo pattern, presentation, and associated conditions?
Answer
Histo: Gland-forming (adenocarcinoma); cohesive cells; grows via intestinal metaplasia pathway Presentation: Ulcerating lesion (often distal/antral); H. pylori association Associations: H. pylori, atrophic gastritis, intestinal metaplasia, smoking, salt intake Metastases: Virchow lymph node (left supraclavicular), Krukenberg (ovarian), Sister Mary Joseph (umbilical)
LO 10 — Gastric Cancer: Diffuse Type
Histology, cell appearance, molecular feature, and growth pattern?
Answer
Histo:Signet-ring cells (mucin-filled, nucleus pushed to side) Pattern:Linitis plastica ("leather bottle" stomach) — diffuse infiltration, poor prognosis Molecular: CDH1 mutations → loss of E-cadherin (cell adhesion) → poor cohesion Spread: Usually metastatic at diagnosis; peritoneal carcinomatosis common
LO 11 — GIST (Gastrointestinal Stromal Tumor)
Cell of origin, key marker, mutation, and drug response?
Answer
Origin: Interstitial cells of Cajal (or their progenitors) → spindle cell sarcoma Marker: CD117 (c-KIT receptor) — strongly positive on immunostain Mutation: c-KIT or PDGFRA gain-of-function mutations Treatment: Imatinib (tyrosine kinase inhibitor blocks c-KIT) — dramatic response Location: Can occur anywhere in GI tract (stomach most common)
LO 12 — MALT Lymphoma
What drives it, how is it diagnosed, and does H. pylori eradication work?
Answer
Driver: H. pylori infection → chronic antigenic stimulation → clonal B-cell proliferation Histology: Marginal zone B-cell lymphoma in mucosa (MALT = Mucosa-Associated Lymphoid Tissue) Diagnosis: Endoscopy + gastric biopsy with flow cytometry/immunostain H. pylori eradication: YES! ~80% of early MALT lymphomas regress after triple/quadruple therapy Prognosis: Indolent; excellent response to H. pylori treatment
LO 13 — H. pylori Diagnostics
Name three diagnostic methods and distinguish invasive vs. non-invasive?
Answer
Invasive (require endoscopy/biopsy): • Silver stain histology: Gold standard; visualize organism in tissue • Culture: Low sensitivity but allows susceptibility testing • Rapid urease test (CLO test): H. pylori urease → ammonia → pH rise → color change Non-invasive: • Stool antigen: Monoclonal Ab to H. pylori antigen • Urea breath test (UBT): Radioactive ¹⁴C-urea → H. pylori urease cleaves it → ¹⁴CO₂ detected in breath Note: All tests have limitations; confirm with ≥2 methods in uncertain cases
Buzzword: MAGGAD Sequence
What does MAGGAD stand for and when is it relevant?
Answer
MAGGAD: Metaplasia → Atrophy → Gastritis → Gastric dysplasia → Adenocarcinoma Applies to: H. pylori-driven chronic gastritis → intestinal-type gastric cancer Timeline: Decades of H. pylori infection; most people never progress Clinical relevance: Rationale for H. pylori screening/eradication in high-risk populations
Buzzword: E-cadherin & Diffuse Gastric Cancer
Why is E-cadherin loss linked to aggressive cancer and what cellular consequence results?
Answer
E-cadherin: Ca²⁺-dependent cell-cell adhesion molecule Loss mechanism: CDH1 gene mutations → loss of adhesion protein → cells lose cohesion Consequence: Individual signet-ring cells detach + migrate → diffuse infiltration → linitis plastica Clinical: Aggressive diffuse-type gastric cancer; poor prognosis; hereditary diffuse gastric cancer (HDGC) syndrome with CDH1 mutation requires surveillance
LO 10 — Gastric Cancer: Classic Metastatic Presentations
What are Virchow, Sister Mary Joseph, and Krukenberg nodes and where do they occur?
Answer
Virchow lymph node: Metastatic left supraclavicular lymph node (left above clavicle) from gastric cancer → "Virchow's sentinel node" Sister Mary Joseph nodule: Metastatic umbilical lymph node → palpable nodule at umbilicus Krukenberg tumor: Metastatic ovarian involvement (via peritoneal seeding) from gastric cancer; usually bilateral; signet-ring cells in ovarian stroma Clinical significance: All indicate advanced/metastatic disease; poor prognosis
Ordering Drills: Arrange each sequence of steps in the correct physiologic or pathologic order. Drag items to reorder. Click "Check Order" to verify, or "Show Answer" to reveal the correct sequence.
H. pylori Infection → Intestinal-Type Gastric Cancer (MAGGAD)
Trace the chronic inflammatory cascade from initial infection to dysplasia.
Chronic atrophic gastritis develops
Dysplasia appears (low-grade, then high-grade)
H. pylori colonizes antral mucosa
Adenocarcinoma develops
Intestinal metaplasia replaces gastric glands
H. pylori colonizes antral mucosa
Chronic atrophic gastritis develops
Intestinal metaplasia replaces gastric glands
Dysplasia appears (low-grade, then high-grade)
Adenocarcinoma develops
Barrett's Esophagus Pathogenesis
From normal esophageal epithelium to cancer risk.
Intestinal metaplasia with goblet cells (Barrett's)
Chronic acid-induced mucosal inflammation
Reflux of gastric contents into lower esophagus
Dysplasia/adenocarcinoma risk increases
Normal non-keratinized squamous epithelium
Normal non-keratinized squamous epithelium
Reflux of gastric contents into lower esophagus
Chronic acid-induced mucosal inflammation
Intestinal metaplasia with goblet cells (Barrett's)
Dysplasia/adenocarcinoma risk increases
HSV Esophagitis Histopathology
From viral invasion to characteristic tissue findings.
Epithelial necrosis at base of ulcers
Viral replication within epithelial cells
Multinucleated giant cells (syncytia) form
HSV invades esophageal mucosa
Punched-out ulcers with fibrin base
HSV invades esophageal mucosa
Viral replication within epithelial cells
Epithelial necrosis at base of ulcers
Multinucleated giant cells (syncytia) form
Punched-out ulcers with fibrin base
Duodenal vs. Gastric Ulcer Pathophysiology
How H. pylori creates duodenal ulcers but direct injury causes gastric ulcers.
Duodenal ulcers form at gastric metaplasia site
H. pylori predominantly colonizes antral mucosa
Antral inflammation + ↑ acid secretion
H. pylori infection acquired
Gastric ulcers: NSAIDs + H. pylori cause direct mucosal injury
H. pylori infection acquired
H. pylori predominantly colonizes antral mucosa
Antral inflammation + ↑ acid secretion
Duodenal ulcers form at gastric metaplasia site
Gastric ulcers: NSAIDs + H. pylori cause direct mucosal injury
Gastric Cancer: Intestinal vs. Diffuse Spread
Two different pathways to adenocarcinoma with distinct molecular drivers.
Diffuse type: E-cadherin loss → poor cohesion
Intestinal type: Arises from metaplasia/dysplasia pathway (MAGGAD)
Two molecular subtypes with distinct progression
Signet-ring cells infiltrate → linitis plastica
Gastric adenocarcinoma develops
Gastric adenocarcinoma develops
Two molecular subtypes with distinct progression
Intestinal type: Arises from metaplasia/dysplasia pathway (MAGGAD)
Diffuse type: E-cadherin loss → poor cohesion
Signet-ring cells infiltrate → linitis plastica
Step 1-Style MCQs: Select the best answer for each question. Your choice locks in immediately and the explanation reveals automatically. Green = correct, Red = incorrect.
Question 1 of 10 — Infectious Esophagitis: HSV
A 34-year-old man with HIV (CD4 50) presents with severe odynophagia and dysphagia. Endoscopy reveals multiple punched-out ulcers with sharp borders and a fibrin base in the distal esophagus. Biopsy is taken. Which histologic finding is MOST specific for this diagnosis?
ACandida hyphae with pseudohyphae in tissue
BMultinucleated giant cells (syncytia) at ulcer base
CLarge cells with "owl-eye" inclusions and ground-glass nuclei
DAcute and chronic inflammation without specific viral cytopathic changes
EGranulomas with caseating necrosis
B — Multinucleated giant cells. HSV causes syncytial formations (multinucleated cells) at the base of ulcers — this is PATHOGNOMONIC for HSV. Candida (A) is shown as hyphae. CMV (C) shows owl-eye inclusions, not multinucleated cells. Nonspecific inflammation (D) is seen with many infections. Granulomas (E) suggest TB or fungal infection. The punched-out ulcer morphology is also classic for HSV.
Question 2 of 10 — GERD/Barrett's Metaplasia
A 52-year-old man with a 20-year history of GERD has a screening endoscopy that shows salmon-pink mucosa in the distal esophagus. Biopsy confirms columnar epithelium with goblet cells. Which of the following correctly describes the metaplastic change that has occurred?
AColumnar mucosa has replaced stratified squamous epithelium; loss of mucin-secreting cells
BNon-keratinized squamous epithelium has been replaced by intestinal-type columnar epithelium with goblet cells
CSquamous epithelium undergoes dysplasia but retains squamous cell morphology
DKeratinized squamous epithelium develops as a protective response to acid
EParietal cells migrate into the esophagus to increase acid buffering
B — Intestinal metaplasia replaces squamous epithelium. Barrett's esophagus is METAPLASIA of the normal esophageal epithelium (non-keratinized squamous) to intestinal-type columnar epithelium WITH goblet cells. Goblet cells are characteristic and confirm intestinal differentiation. This is true metaplasia — reversible if caught early and H. pylori (or GERD) is treated. (A) is backwards; (C) is dysplasia not metaplasia; (D/E) are incorrect mechanisms.
Question 3 of 10 — Esophageal Cancer: SCC vs. Adenocarcinoma
A 55-year-old man with a 30-pack-year smoking history and heavy alcohol use presents with progressive dysphagia. Upper endoscopy identifies a stricturing lesion in the middle third of the esophagus. Biopsy shows squamous cell carcinoma. Which of the following is the BEST explanation for why this tumor arose in this location and cell type?
AThe esophagus is lined by squamous epithelium; smoking/alcohol cause SCC in this location; adenocarcinoma occurs lower (Barrett's region)
BH. pylori infection caused metaplasia throughout the esophagus, predisposing to adenocarcinoma
CSmoking causes Barrett's esophagus in the upper third, leading to SCC
DAdenocarcinoma is more common in this region due to H. pylori seeding
EBoth SCC and adenocarcinoma have equal incidence; location does not predict type
A — SCC in upper/middle third, adenocarcinoma in lower third. Esophageal adenocarcinoma arises from Barrett's (intestinal metaplasia in distal esophagus/GE junction), while SCC arises from the normal squamous epithelium of the upper and middle esophagus (smoking + alcohol are major risk factors). In the US, adenocarcinoma is now MORE common overall, but SCC in upper regions is still classic. Barrett's (choice C) does not arise from smoking directly — it arises from GERD.
Question 4 of 10 — H. pylori Location & Duodenal Ulcers
A 40-year-old man with a chronic cough is found to have H. pylori infection on serology. He reports no prior gastrointestinal symptoms but has a strong family history of peptic ulcer disease. Which of the following BEST explains why H. pylori is associated with duodenal ulcers rather than just causing inflammation everywhere in the stomach?
AH. pylori directly invades the duodenum and causes necrotizing inflammation
BH. pylori colonizes the antrum → increases gastric acid → causes gastric metaplasia in duodenum → ulcers form at metaplastic sites
CH. pylori is exclusively found in the duodenum and causes localized ulceration
DThe duodenum lacks protective mucus, making it uniquely vulnerable to any infection
B — H. pylori in antrum → acid ↑ → gastric metaplasia in duodenum. H. pylori preferentially colonizes the antral mucosa. Antral inflammation + bacterial urease → increased acid secretion. The excess acid then damages the duodenum, which normally has less protective mucus than the stomach. Additionally, gastric metaplasia (columnar mucosa) develops in the duodenum in response to acid, and H. pylori can then colonize these metaplastic sites → ulcers. Choice (A) is incorrect because H. pylori doesn't directly live in the duodenum in large numbers.
Question 5 of 10 — Gastric Cancer: Intestinal Type
A 58-year-old Japanese man is found on screening endoscopy to have an ulcerating mass in the distal stomach. Biopsy shows adenocarcinoma with gland formation. He has a history of H. pylori infection diagnosed 15 years ago (never treated) and chronic gastric inflammation. Which of the following represents the MOST likely carcinogenic pathway for this tumor?
CH. pylori causes rapid transformation to adenocarcinoma within 1–2 years
DNSAIDs are the primary carcinogen; H. pylori plays a minor role
EPernicious anemia from vitamin B12 deficiency causes direct malignant transformation
B — MAGGAD: Metaplasia → Atrophy → Gastritis → Gastric dysplasia → Adenocarcinoma. This is the canonical pathway for intestinal-type gastric cancer driven by chronic H. pylori infection. The gland-forming histology and ulcerating presentation fit the intestinal-type pattern. The 15-year timeline also matches the chronic progression. Signet-ring (choice A) describes diffuse-type cancer. The transformation takes decades, not 1–2 years (C).
Question 6 of 10 — GIST: Molecular Marker & Treatment
A 62-year-old woman with a gastric stromal tumor is found to have a c-KIT gain-of-function mutation. Immunohistochemistry shows strong positivity for CD117. The tumor is unresectable. Which of the following treatment strategies is MOST likely to produce a durable response?
BImatinib, a tyrosine kinase inhibitor targeting c-KIT
CRadiation therapy to induce apoptosis of stromal cells
DH. pylori eradication therapy (same as MALT lymphoma)
ESupportive care; GISTs are always fatal despite treatment
B — Imatinib (tyrosine kinase inhibitor). GIST is defined by c-KIT (CD117) activation. Imatinib is a selective inhibitor of c-KIT and PDGFRA tyrosine kinases — it produces dramatic clinical responses in GIST, even in metastatic disease. This is a triumph of targeted therapy. Chemotherapy (A) is ineffective. Radiation (C) doesn't work well for GIST. H. pylori therapy (D) is for MALT lymphoma, not GIST. GISTs have improved outcomes with imatinib (E is false).
Question 7 of 10 — Acute Gastritis: Curling vs. Cushing
A 24-year-old man who suffered severe thermal burns over 40% of his body develops acute gastric ulcers 3 days post-injury. A second patient with a traumatic brain injury develops similar ulcers. Which of the following CORRECTLY distinguishes the pathophysiology of these two scenarios?
ABoth are caused by stress-induced increases in gastric acid secretion
BBurn injuries cause increased acid; brain injury causes decreased motility
CCurling (burn) ulcers result from systemic hypoperfusion/ischemia; Cushing (CNS) ulcers from ↑gastric acid via ↑vagal tone
DBoth require high-dose PPI therapy; neither responds to acid suppression alone
EBrain injury ulcers are complications of increased ICP, not true peptic ulcers
C — Curling = ischemia from hypovolemia; Cushing = ↑acid from ↑vagal tone.Curling ulcers follow severe burns: massive fluid loss → hypovolemia → splanchnic hypoperfusion → mucosal ischemia → ulcers. Cushing ulcers follow CNS trauma: increased ICP/vagal stimulation → ↑↑HCl secretion → direct mucosal damage from excess acid. Both are acute stress ulcers, but the mechanisms differ. Both respond well to PPIs, especially Cushing ulcers (acid suppression is curative). Choice (A) oversimplifies — Curling is primarily ischemic, not just acid.
Question 8 of 10 — Autoimmune Gastritis vs. H. pylori
A 67-year-old woman presents with vitamin B12 deficiency and achlorhydria (pH >5). Serum gastrin is elevated (145 pg/mL). Biopsy from the fundus of the stomach shows marked atrophy with lymphocytic infiltration. H. pylori serology is negative. Which of the following is the primary mechanism driving her symptoms?
AH. pylori has destroyed all gastric glands despite negative serology
BAutoimmune destruction of parietal cells → loss of HCl + intrinsic factor → ↑gastrin (lost feedback inhibition) → B12 malabsorption
CGastric atrophy is age-related; elevated gastrin is a normal variant in elderly
DReduced acid is due to atrophic gastritis secondary to chronic NSAIDs
EElevated gastrin indicates a gastrin-secreting tumor (ZES)
B — Autoimmune parietal cell destruction → achlorhydria → elevated gastrin. Autoimmune gastritis specifically attacks parietal cells in the fundus/body of stomach (not antral like H. pylori). Loss of parietal cells → loss of HCl AND intrinsic factor. Intrinsic factor is required for B12 absorption in the terminal ileum → pernicious anemia. Achlorhydria means no negative feedback on gastrin secretion → ↑↑gastrin. H. pylori is excluded by negative serology and fundal (not antral) location. The elevated gastrin here is appropriate for achlorhydria — not ZES (which would have even higher levels and is from a tumor).
Question 9 of 10 — MALT Lymphoma & H. pylori
A 45-year-old man is found on screening endoscopy to have early-stage gastric MALT lymphoma (mucosa-associated lymphoid tissue lymphoma). H. pylori serology is positive. Which of the following is the MOST appropriate initial management?
AObserve with serial endoscopy; lymphoma is indolent and rarely progresses
BH. pylori eradication therapy (triple or quadruple therapy); ~80% of early MALT lymphomas regress
CImmediate chemotherapy to target clonal B cells
DSubtotal gastrectomy to remove all lymphoid tissue
B — H. pylori eradication is the gold standard for early MALT lymphoma. MALT lymphoma is driven by chronic antigenic stimulation from H. pylori. Eradicating the organism removes the stimulus for B-cell proliferation → regression of lymphoma in ~80% of cases (especially early-stage). This is a unique example where treating the infectious cause can cure a lymphoma. Rituximab and chemotherapy are reserved for MALT lymphomas that progress despite H. pylori treatment or high-grade lymphomas. Observation alone risks progression.
Question 10 of 10 — H. pylori Diagnostics
A 38-year-old woman with a history of peptic ulcer disease is being evaluated for successful H. pylori eradication after completing triple therapy 2 weeks ago. Which of the following is the LEAST reliable test to confirm successful eradication at this time point?
AUrea breath test (UBT) with ¹⁴C-labeled urea
BSerology for anti-H. pylori IgG antibodies
CStool antigen test (monoclonal anti-H. pylori)
DEndoscopy with gastric biopsy for rapid urease test (CLO)
EGastric biopsy with silver stain histology
B — Serology is NOT useful for confirming eradication. Serology (anti-H. pylori IgG) remains positive for months to years after successful eradication — antibodies don't disappear quickly. UBT (A), stool antigen (C), rapid urease test (D), and histology (E) all detect CURRENT infection and are useful for test-of-cure (ideally 4+ weeks post-therapy). Serology is good for initial diagnosis but not for confirming eradication. The patient was correctly treated 2 weeks ago; now she needs a test that confirms the organism is gone, not one that measures past immune response.
Vignette MCQs: Full clinical scenarios with realistic presentations. Read the entire patient story before answering.
Vignette 1 — Infectious Esophagitis in Immunocompromised
HPI: A 29-year-old man with recently diagnosed HIV (CD4 32 cells/μL) presents to the ED with 1 week of severe odynophagia, dysphagia, and 2–3 kg weight loss. He denies hematemesis. Exam: Oropharyngeal candidiasis noted (white plaques on tongue). Labs: Normal CBC, LFTs normal. Imaging: CXR clear. Endoscopy: Multiple discrete punched-out ulcers with fibrin base scattered throughout the distal esophagus; few normal intervening areas. Biopsy result pending. What is the MOST likely diagnosis?
ACandida esophagitis (thrush extending to esophagus)
EEsophageal cancer (rapidly progressive dysphagia)
B — HSV esophagitis. The punched-out ulcer morphology is classic and PATHOGNOMONIC for HSV. Candida (A) presents as white plaques/pseudomembranes, not punched-out ulcers (though candidiasis is common in AIDS). CMV (C) shows large linear/longitudinal ulcers with owl-eye inclusions on biopsy, not punched-out lesions. The CD4 of 32 makes all three opportunistic infections possible, but the endoscopic appearance defines HSV. Biopsy will show multinucleated giant cells to confirm.
Vignette 2 — GERD → Barrett's with Dysplasia
HPI: A 58-year-old overweight man with 25 years of GERD (treated intermittently with H2 blockers, never tried PPIs) undergoes surveillance endoscopy. Findings: Long-segment Barrett's esophagus (8 cm of salmon-pink mucosa in distal esophagus). Biopsy from the Barrett's segment shows high-grade dysplasia. Question: Which of the following BEST describes his malignant risk and next step?
ADysplasia is benign; close observation with repeat endoscopy in 5 years is adequate
BHigh-grade dysplasia carries ~60% risk of occult adenocarcinoma; endoscopic mucosal resection or esophagectomy recommended
CBarrett's with dysplasia is curable with PPIs alone; no endoscopic intervention needed
DDysplasia is a sign of metaplasia reversal; prognosis is excellent
ERadiofrequency ablation is contraindicated due to high recurrence risk
B — High-grade dysplasia has high malignancy risk; intervention required. High-grade dysplasia in Barrett's carries ~60% risk of occult adenocarcinoma and progression. Management includes endoscopic mucosal resection (EMR) for surveillance and radiofrequency ablation (RFA) to ablate dysplastic mucosa. PPI therapy alone (C) does NOT reverse dysplasia or prevent cancer. Observation (A) is inadequate for high-grade dysplasia. The patient's decades of GERD and only intermittent treatment explain the progression to long-segment Barrett's.
Vignette 3 — H. pylori & Duodenal Ulcer
HPI: A 44-year-old woman with a 3-year history of epigastric pain (worse at night, relieved by food/antacids) is found to have an active duodenal ulcer on upper endoscopy. Rapid urease test (CLO test) is positive. Question: In addition to the duodenal ulcer location, which other finding supports H. pylori as the primary etiology in this patient?
APain is worse with food; this is classic for H. pylori duodenal ulcers
BPain relieved by food/antacids and ulcer in duodenum (NOT stomach) suggests H. pylori; duodenal ulcers more common with H. pylori than NSAIDs
CThe positive CLO test proves H. pylori, but NSAIDs are the more likely cause overall
DFemale gender and age <50 years rule out H. pylori; acid hypersecretion is likely
EThe pain pattern indicates stress-related ulcers; H. pylori is not relevant
B — Duodenal ulcer location + pain relieved by food = classic for H. pylori. H. pylori causes ~90% of duodenal ulcers (vs. NSAIDs causing most gastric ulcers). The pain pattern (epigastric, relieved by food/antacids) is typical for duodenal ulcer physiology: increased gastric acid is buffered by food. The CLO test confirms active H. pylori. The duodenal location is key because gastric ulcers are more associated with NSAIDs. Stress ulcers (E) are acute and post-trauma/surgical, not chronic pain for 3 years.
Vignette 4 — Gastric Cancer: Diffuse Type
HPI: A 55-year-old Korean woman presents with 6 months of early satiety, weight loss (8 kg), and mild epigastric pain. Exam: Thin, cachetic appearance; no palpable masses. Imaging: CT shows diffuse gastric wall thickening with reduced lumen (linitis plastica); peritoneal deposits noted. Endoscopy: Rigid, narrowed stomach with ulceration. Biopsy:Signet-ring cell adenocarcinoma.Question: Which genetic alteration is MOST associated with this histologic type and aggressive behavior?
ATP53 mutation causing loss of tumor suppression
BCDH1 mutation → E-cadherin loss → loss of cell-cell adhesion → individual signet-ring cells infiltrate
Cc-KIT mutations (seen in GIST, not gastric cancer)
DKRAS activation from H. pylori chronic infection
EHigh microsatellite instability from mismatch repair deficiency
B — CDH1 mutation → E-cadherin loss → signet-ring cells. Diffuse-type gastric cancer is characterized by signet-ring cells (single, mucin-filled cells with eccentric nucleus) that have lost cell cohesion. This is driven by CDH1 gene mutations → loss of E-cadherin (adhesion protein) → cells detach from neighbors → individual cell infiltration → linitis plastica ("leather bottle" appearance). This pattern is more aggressive and metastasizes early (peritoneal deposits in this case). Korean ethnicity is a risk factor. Hereditary Diffuse Gastric Cancer (HDGC) syndrome from CDH1 mutations carries very high cancer risk.
Vignette 5 — MALT Lymphoma Regression
HPI: A 52-year-old woman presents with vague epigastric discomfort and dyspepsia. Endoscopy shows multiple nodular lesions in the gastric mucosa. Biopsy: MALT lymphoma (marginal zone B-cell lymphoma); H. pylori stain POSITIVE. Labs: No hepatosplenomegaly, normal LDH. CT staging: No distant lymphadenopathy. Question: What is the MOST appropriate management?
AImmediate chemotherapy (CHOP) given lymphoma diagnosis
BH. pylori eradication therapy (PPI + amoxicillin + clarithromycin) followed by surveillance endoscopy in 3 months
CSubtotal gastrectomy to remove lymphoid tissue
DObservation alone; MALT lymphomas are usually indolent and don't require treatment
ERituximab (anti-CD20 monoclonal antibody) for initial treatment
B — H. pylori eradication is the first-line treatment for H. pylori-positive MALT lymphoma. MALT lymphoma is fundamentally driven by chronic H. pylori antigenic stimulation. Eradicating H. pylori with triple therapy removes the stimulus → lymphoma regresses in ~80% of cases (especially early-stage, localized disease like this patient). Repeat endoscopy in 3 months confirms regression. Chemotherapy (A), surgery (C), or rituximab (E) are reserved for MALT lymphomas that progress despite H. pylori treatment or high-grade components. This patient has early-stage, H. pylori-dependent disease → H. pylori therapy is curative.
Step 1 Traps: Classic confusions and board-exam distractors. Choose the correct statement vs. the trap.
Trap 1
TRAP: "CMV esophagitis causes punched-out ulcers with multinucleated giant cells (same as HSV)."
CORRECT: CMV causes LARGE LINEAR/LONGITUDINAL ulcers, NOT punched-out. Histo shows owl-eye inclusions (large cell nucleus with smudged appearance), NOT multinucleated giant cells. This is a classic Step 1 distinction: HSV = punched-out + syncytia; CMV = linear + owl-eye. Mixing them up is a common error.
WRONG: CMV and HSV are NOT the same. The ulcer morphology and histology are distinctly different — this is a heavily tested distinction on exams.
Trap 2
TRAP: "Barrett's esophagus is a DYSPLASIA — once diagnosed, the squamous epithelium is permanently damaged and will always progress to cancer."
CORRECT: Barrett's esophagus is a METAPLASIA (reversible change in cell type), NOT dysplasia. The key is that metaplasia can regress if the stimulus (GERD) is controlled EARLY with aggressive PPI therapy. If Barrett's is left untreated and H. pylori eradication is done late, dysplasia may develop (which is NOT reversible). Students often conflate Barrett's (metaplasia) with dysplasia (irreversible).
WRONG: Metaplasia is not the same as dysplasia. Barrett's CAN regress in some cases, especially if caught early and GERD is aggressively managed. Dysplasia is irreversible, but Barrett's itself is reversible metaplasia.
Trap 3
TRAP: "Duodenal and gastric ulcers are caused by the same etiologies (H. pylori or NSAIDs) — the location depends only on chance."
CORRECT: Duodenal ulcers are predominantly H. pylori-driven (~90%), while gastric ulcers are more commonly caused by NSAIDs. The reason: H. pylori colonizes the antrum, increasing acid secretion, which damages the duodenum. Gastric ulcers result from direct mucosal damage (NSAIDs ± H. pylori). Additionally, duodenal ulcer pain is RELIEVED by food (buffering acid), while gastric ulcer pain is WORSE with food. These distinctions matter on boards.
WRONG: The etiologies, locations, and pain patterns of duodenal vs. gastric ulcers are systematically different. This is heavily tested; assuming they're equivalent is a trap.
Trap 4
TRAP: "Autoimmune gastritis destroys gastric glands in the ANTRUM (same as H. pylori) and causes elevated gastrin because of ↑acid secretion."
CORRECT: Autoimmune gastritis attacks the FUNDUS/BODY (parietal cells), NOT antrum. H. pylori attacks the antrum. Autoimmune gastritis → loss of parietal cells → achlorhydria (NO acid) → ↑↑gastrin (NO negative feedback). In contrast, H. pylori causes hyperacidity initially. The raised gastrin in autoimmune gastritis is due to LACK of acid, not excess. This location and mechanism distinction is crucial.
WRONG: Autoimmune and H. pylori gastritis are in DIFFERENT locations (fundus vs. antrum) and cause OPPOSITE acid changes. Confusing them is a classic board trap.
Trap 5
TRAP: "Gastric MALT lymphoma and gastric adenocarcinoma have similar prognoses and require chemotherapy."
CORRECT: MALT lymphoma and adenocarcinoma are ENTIRELY DIFFERENT and have opposite prognoses. MALT lymphoma is indolent, H. pylori-driven, and ~80% regress with H. pylori eradication alone — NO chemotherapy needed for early disease. Adenocarcinoma is aggressive, multifactorial (H. pylori, NSAIDs, smoking), and DOES require surgery/chemo. The key differentiator is that MALT lymphoma is cured by treating H. pylori; adenocarcinoma is not.
WRONG: MALT lymphoma and adenocarcinoma are fundamentally different diseases with different management. Thinking they're the same leads to wrong treatment decisions.
Trap 6
TRAP: "E-cadherin loss is seen in both intestinal-type and diffuse-type gastric cancers; it's a pan-gastric cancer marker."
CORRECT: E-cadherin loss (CDH1 mutations) is SPECIFIC to diffuse-type gastric cancer (signet-ring cells, linitis plastica). Intestinal-type gastric cancer arises from the MAGGAD sequence (H. pylori-driven metaplasia/dysplasia) and does NOT have CDH1 loss. This molecular distinction determines histology: intestinal-type = gland-forming; diffuse-type = signet-ring cells detached from neighbors. On exams, CDH1 mutations → think diffuse-type, not intestinal.
WRONG: E-cadherin loss is NOT a pan-gastric cancer marker — it's specific to the diffuse-type pathway. Intestinal-type gastric cancers have a different molecular driver (chronic inflammation/metaplasia).
Trap 7
TRAP: "Serology for anti-H. pylori antibodies (IgG) is the gold standard for confirming H. pylori eradication after therapy."
CORRECT: Serology is USELESS for test-of-cure. IgG antibodies persist for months to years after successful eradication — a positive serology just means the patient WAS infected at some point, not that they ARE currently infected. Use UBT (urea breath test), stool antigen, or repeat CLO test (rapid urease) from endoscopy to confirm eradication. Serology is good for initial diagnosis (ruling out H. pylori in a seronegative patient) but NOT for assessing cure.
WRONG: This is a heavily tested mistake. Students often use serology for test-of-cure and get it wrong. Remember: serology for diagnosis; UBT/stool antigen/CLO for eradication confirmation.
Trap 8
TRAP: "Curling ulcers (burn injuries) and Cushing ulcers (CNS trauma) are caused by the same mechanism: increased gastric acid secretion."
CORRECT: These are OPPOSITE mechanisms: • Curling: Severe burns → hypovolemia → splanchnic hypoperfusion → mucosal ISCHEMIA (not excess acid) • Cushing: CNS injury/↑ICP → ↑vagal tone → ↑↑acid secretion Students often confuse them by thinking both are stress-related and acid-driven. The key is Curling is ischemic (low flow), while Cushing is acid-driven (high acid). Treatment differs: Curling benefits from volume resuscitation; Cushing benefits from PPIs.
WRONG: Curling and Cushing have opposite etiologies — mixing them up leads to wrong explanations on Step 1.