A 63-year-old man comes to the physician because of a 2-month history of progressive fatigue. He also has shortness of breath and palpitations, which worsen on physical exertion and improve with rest. He has had intermittent constipation, low-grade fever, and generalized myalgia for the past 3 months. He has had a 10.4-kg (23-lb) weight loss over the past 4 months despite no change in appetite. His temperature is 37°C (98.6°F), pulse is 108/min, respirations are 16/min, and blood pressure is 130/78 mm Hg. Examination shows pale conjunctivae. His hemoglobin concentration is 9.1 g/dL, mean corpuscular volume is 70 μm3, and serum ferritin is 12 ng/mL. Test of the stool for occult blood is positive. Colonoscopy shows a 1.7-cm wide exophytic ulcer with irregular, bleeding edges in the ascending colon. Which of the following biopsy findings would have been the greatest predisposing factor for developing this patient's current condition?

A pedunculated inflammatory polyp

A 41-year-old male who takes NSAIDs regularly for his chronic back pain develops severe abdominal pain worse with eating. Upper endoscopy is performed and the medical student asks the supervising physician how the histological differentiation between a gastric ulcer and erosion is made. Which of the following layers of the gastric mucosa MUST be breached for a lesion to be considered an ulcer?

Epithelium, lamina propria, muscularis mucosa

Epithelium, lamina propria, muscularis mucosa, submucosa, and adventitia

Epithelium, lamina propria, muscularis mucosa, and submucosa

A 53-year-old man comes to the physician because of fatigue, recurrent diarrhea, and an 8-kg (17.6-lb) weight loss over the past 6 months. He has a 4-month history of recurrent blistering rashes on different parts of his body that grow and develop into pruritic, crusty lesions before resolving spontaneously. Physical examination shows scaly lesions in different phases of healing with central, bronze-colored induration around the mouth, perineum, and lower extremities. Laboratory studies show: Hemoglobin 10.1 mg/dL Mean corpuscular volume 85 μm3 Mean corpuscular hemoglobin 30.0 pg/cell Serum Glucose 236 mg/dL Abdominal ultrasonography shows a 3-cm, solid mass located in the upper abdomen. This patient's mass is most likely derived from which of the following types of cells?

Gastrointestinal enterochromaffin cells

A 61-year-old man comes to the physician because of a 6-month history of epigastric pain and a 9-kg (20-lb) weight loss. He feels full and bloated even after eating small portions of food. His hemoglobin concentration is 9.5 g/dL with a mean corpuscular volume of 78 μm3. Test of the stool for occult blood is positive. Esophagogastroduodenoscopy shows a 2-cm raised lesion with central ulceration on the lesser curvature of the stomach. Histologic examination of a gastric biopsy specimen from the lesion is most likely to show which of the following?

Neutrophilic infiltration with pit abscesses

Lymphocytic aggregates with noncaseating granulomas

Foveolar and smooth muscle hyperplasia

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

"Can you tell me more about the symptoms you have been experiencing?"

"Does the diarrhea typically precede the constipation, or vice-versa?"

"Is the diarrhea foul-smelling?"

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

"Are the symptoms worse in the morning or at night?"

A 75-year-old man comes to his primary care physician because he has been having diarrhea and difficulty breathing. The diarrhea has been intermittent with frequent watery stools that occur along with abdominal cramps. Furthermore, the skin on his face and upper chest feels hot and changes color in episodes lasting from a few minutes to hours. Finally, the patient complains of loss of appetite and says that he has unexpectedly lost 20 pounds over the last two months. Based on clinical suspicion, magnetic resonance imaging is obtained showing a small mass in this patient's lungs. Which of the following is associated with the most likely cause of this patient's symptoms?

Has keratin pearls and intercellular bridges

Most common lung cancer in non-smokers and females

Gastric tumors for USMLE Step 1: High-Yield Pathology Lessons

Benign & Precursor Lesions - Tummy Bumps & Worries

Endoscopic view of gastric polyp with ulceration

Hyperplastic Polyps: Most common (~75%). Inflammatory proliferation, often with H. pylori gastritis. Low malignant potential.
Fundic Gland Polyps: Associated with PPI use; sporadic. Cystically dilated glands. No malignant potential.
Adenomatous Polyps: True neoplasms. Malignant potential ↑ with size (>2 cm) and villous features. Precursor to adenocarcinoma.
Chronic Gastritis: H. pylori drives progression: Atrophy → Intestinal Metaplasia → Dysplasia → Cancer.

⭐ Most intestinal-type gastric adenocarcinomas arise from precursor lesions, particularly adenomas and chronic gastritis-induced intestinal metaplasia.

Gastric Adenocarcinoma I - The Cancerous Crater

Most common stomach cancer, with high rates in East Asia. Major risk factors include chronic H. pylori infection, dietary nitrosamines (smoked foods), smoking, and Blood Type A.

Gastric adenocarcinoma with ulcerated crater

Lauren Classification:

Feature	Intestinal Type	Diffuse Type (Linitis Plastica)
Appearance	Forms bulky, ulcerating masses; glandular.	Infiltrates wall; signet ring cells. Thickened, leathery appearance.
Pathogenesis	Linked to H. pylori, intestinal metaplasia.	Not associated with H. pylori; CDH1/E-cadherin mutation.
Prognosis	Better; hematogenous spread.	Worse; early transmural/lymphatic spread.

Gastric Adenocarcinoma II - Spotting the Stomach Sneak

Morphology & Location
- Linitis Plastica: Diffuse infiltration of the stomach wall, creating a rigid, leather bottle appearance. Poor prognosis.
- Ulcerated: Large, irregular ulcer with heaped-up margins.
- Most common on the lesser curvature of the antrum.

Linitis plastica gross specimen with thickened stomach wall

Clinical & Paraneoplastic Signs
- Weight loss, abdominal pain, early satiety.
- Acanthosis Nigricans: Velvety, hyperpigmented plaques in flexural areas.
- Leser-Trélat Sign: Sudden eruption of multiple seborrheic keratoses.
Metastatic Spread
- Virchow Node: Left supraclavicular node.
- Sister Mary Joseph Nodule: Periumbilical subcutaneous nodule.
- Krukenberg Tumor: Bilateral ovarian metastasis.

⭐ The Leser-Trélat sign, the abrupt appearance of numerous seborrheic keratoses, is a dramatic cutaneous marker strongly associated with an underlying gastric adenocarcinoma.

Other Gastric Tumors - The Stomach's Oddballs

GIST: Gross and Microscopic Pathology

Tumor	Origin / Cell	Key Association / Mutation	Treatment
Gastric Lymphoma (MALToma)	MALT tissue (B-cells)	Chronic H. pylori infection	Eradicate H. pylori (first-line)
GIST	Interstitial Cells of Cajal	c-KIT (CD117) gene mutation	Imatinib (tyrosine kinase inhibitor)
Carcinoid Tumor	Neuroendocrine (ECL) cells	Chronic atrophic gastritis, hypergastrinemia	Surgical resection

High‑Yield Points - ⚡ Biggest Takeaways

H. pylori is the strongest risk factor for both gastric adenocarcinoma and MALT lymphoma.

Intestinal-type adenocarcinoma is common and gland-forming; diffuse-type has signet ring cells causing linitis plastica.

Metastatic signs: Virchow's node (supraclavicular), Krukenberg tumor (ovarian), and Sister Mary Joseph nodule (periumbilical).

Gastrointestinal Stromal Tumors (GISTs) arise from the interstitial cells of Cajal and are c-KIT (CD117) positive.

MALT lymphomas may regress completely with H. pylori eradication.

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Gastric tumors