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PA23.1-9 | Gastrointestinal Tract — Practice Quiz
Practice
14 questions · Untimed · Unlimited attempts
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A 52-year-old male tobacco-chewer presents with a white, non-scrapable patch on the buccal mucosa. Biopsy shows epithelial dysplasia without invasion. Which statement best describes the malignant transformation rate of this lesion compared to oral submucous fibrosis (OSMF)?
A
Leukoplakia transforms in ~5% of cases; OSMF has a higher transformation rate of ~7–12%
B
Both lesions transform at an equal rate of ~5% and carry the same histological risk markers
C
OSMF is not a premalignant condition; only leukoplakia with dysplasia confers cancer risk
D
Erythroplakia carries the highest single-lesion risk (~50%), higher than either leukoplakia or OSMF alone
✓
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A 60-year-old male chronic smoker from rural India presents with progressive dysphagia to solids. Upper GI endoscopy reveals an ulcero-proliferative lesion in the mid-oesophagus. Histology shows nests of squamoid cells with keratin pearls. Which aetiological factor is MOST strongly linked to this type of oesophageal carcinoma in this demographic?
A
Chronic gastro-oesophageal reflux disease leading to Barrett's metaplasia
B
Helicobacter pylori infection causing proximal spread to the oesophagus
C
Tobacco and alcohol use, nutritional deficiencies, and achalasia
✓
D
Coeliac disease and associated villous atrophy
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Barrett's oesophagus is diagnosed when the normal squamous epithelium of the lower oesophagus is replaced by a specialised type of metaplastic epithelium. Which single feature is REQUIRED for the histological diagnosis of Barrett's oesophagus?
A
Specialised intestinal metaplasia with goblet cells confirmed by Alcian blue staining
✓
B
Columnar epithelium with gastric-type foveolar cells only (no goblet cells required)
C
High-grade dysplasia at the squamocolumnar junction
D
Submucosal glandular proliferation with Brunner-type glands
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CLINICAL VIGNETTE: A 45-year-old teacher presents with a 3-month history of epigastric pain that worsens 2–3 hours after meals and is relieved by antacids. He uses ibuprofen regularly for knee pain. Endoscopy reveals a 1.2 cm sharply punched-out ulcer on the posterior wall of the duodenal bulb. Antral biopsy is positive for Helicobacter pylori. Which mechanism best explains how H. pylori promotes ulcer formation?
A
H. pylori directly secretes hydrochloric acid, increasing luminal acidity above pH 1
B
H. pylori stimulates D-cell somatostatin release, paradoxically increasing parietal cell acid secretion
C
H. pylori inhibits COX-1, reducing prostaglandin E2 synthesis in the gastric epithelium
D
H. pylori urease produces ammonia, disrupts the mucus barrier, and CagA/VacA virulence factors impair mucosal defence
✓
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Microscopic examination of a resected peptic ulcer reveals four distinct histological zones from the luminal surface inward. Which sequence correctly lists these zones in order from surface to base?
A
Fibrinous exudate → necrotic debris → granulation tissue → fibrous scar
✓
B
Necrotic debris → fibrinous exudate → fibrous scar → granulation tissue
C
Granulation tissue → fibrous scar → necrotic debris → fibrinous exudate
D
Fibrous scar → granulation tissue → fibrinous exudate → necrotic debris
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A surgical resection specimen shows a gastric ulcer 3 cm in diameter along the lesser curvature. The pathologist must distinguish a benign peptic ulcer from a malignant ulcer (carcinoma). Which feature on gross examination would MOST strongly suggest malignancy?
A
Punched-out appearance with smooth, regular margins and flat overhanging edges
B
Irregular, heaped-up, everted edges with a nodular indurated base
✓
C
Ulcer base formed by muscularis propria fused to the pancreas (penetration)
D
Mucosal folds converging symmetrically towards the ulcer margin ('radiating folds')
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Gastric carcinoma of the 'diffuse' type (Lauren classification) is characterised by which of the following histological and clinical features?
A
Signet-ring cells diffusely infiltrating the stomach wall, linitis plastica, occurs in younger patients, worse prognosis
✓
B
Gland-forming intestinal-type pattern, associated with H. pylori chronic gastritis, relatively better prognosis
C
Polypoid tumour arising in the antrum with lymph-node involvement and elevated CEA
D
Ovarian metastasis (Krukenberg tumour) exclusively via haematogenous spread
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A 30-year-old male presents with colicky right iliac fossa pain, low-grade fever, and weight loss over 4 months. Colonoscopy shows discontinuous ('skip') lesions, cobblestone mucosa, and deep fissuring ulcers predominantly in the terminal ileum. Histology reveals non-caseating granulomas in all layers of the bowel wall. Which feature helps distinguish this condition from intestinal tuberculosis?
A
Caseating granulomas and submucosal Langhans giant cells are seen in Crohn's disease but not in intestinal TB
B
Skip lesions, transmural inflammation, non-caseating granulomas, and longitudinal fissuring ulcers favour Crohn's; caseating granulomas and transverse ulcers favour TB
✓
C
Crohn's disease characteristically causes transverse ulcers; TB causes longitudinal fissuring ulcers
D
Both conditions are histologically indistinguishable and require only clinical correlation
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CLINICAL VIGNETTE: A 25-year-old woman presents with 6 months of crampy lower abdominal pain, bloody diarrhoea (8 stools/day), and tenesmus. Colonoscopy reveals continuous mucosal inflammation beginning at the rectum and extending proximally to the splenic flexure, with pseudopolyps. Biopsies show crypt abscesses, goblet-cell depletion, and mucosal inflammation without granulomas. Which single histological feature in this biopsy MOST strongly favours ulcerative colitis over Crohn's colitis?
A
Transmural lymphoid aggregates extending through all layers of the bowel wall
B
Crypt abscesses confined to mucosa/submucosa with goblet-cell depletion and no granulomas
✓
C
Deep fissuring ulcers with submucosal and mesenteric fat involvement ('fat wrapping')
D
Non-caseating granulomas in the lamina propria
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A 35-year-old woman presents with 2 years of diarrhoea, bloating, and weight loss. She has iron-deficiency anaemia and folate deficiency. Anti-tissue transglutaminase (anti-tTG) IgA antibody titre is markedly elevated. Duodenal biopsy shows subtotal villous atrophy with crypt hyperplasia and increased intraepithelial lymphocytes. Which HLA haplotype confers the strongest genetic susceptibility to this condition?
A
HLA-B27 (class I), present in >90% of affected patients
B
HLA-DR3 and HLA-B8 exclusively (no class II DQ involvement)
C
HLA-A, -B, -C loci (class I) — no class II association has been established
D
HLA-DQ2 and HLA-DQ8 (class II), which present deamidated gliadin peptides to CD4+ T cells
✓
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Acute appendicitis most commonly presents with neutrophilic infiltration of the appendiceal wall. Which histological finding is considered the MINIMUM criterion for confirming the diagnosis of acute appendicitis on biopsy?
A
Lymphoid hyperplasia of the appendiceal mucosa without transmural inflammation
B
Neutrophilic infiltration confined to the mucosa with mucosal ulceration only
C
Neutrophilic infiltration of the muscularis (muscularis mucosae or muscularis propria), even if focal
✓
D
Full transmural neutrophilic infiltration with gangrenous necrosis of all layers
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The adenoma-carcinoma sequence in colorectal carcinoma (CRC) involves sequential accumulation of genetic mutations. Which gene is FIRST mutated (the 'gatekeeper' mutation) in the classical Vogelstein pathway, and which syndrome arises from its germline loss?
A
APC tumour suppressor gene; familial adenomatous polyposis (FAP)
✓
B
KRAS oncogene; hereditary non-polyposis colorectal cancer (Lynch syndrome)
C
TP53 tumour suppressor gene; Li-Fraumeni syndrome
D
SMAD4 gene; juvenile polyposis syndrome
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CLINICAL VIGNETTE: A 68-year-old male smoker presents with a 4-month history of change in bowel habit (alternating constipation and diarrhoea) and pencil-thin stools. CT colonography shows a circumferential 'apple-core' lesion in the sigmoid colon. CEA is elevated at 18 ng/mL. He has no family history of polyposis. Which statement about right-sided vs left-sided colorectal carcinoma is CORRECT?
A
Right-sided CRC typically presents early with bowel obstruction; left-sided CRC causes occult bleeding and iron-deficiency anaemia
B
CEA is elevated only in right-sided CRC and is not useful for monitoring left-sided disease recurrence
C
Left-sided CRC grows circumferentially causing obstruction and altered bowel habit; right-sided CRC is exophytic and presents with occult bleeding and anaemia
✓
D
Both right- and left-sided CRC present identically; the anatomical distinction is clinically irrelevant
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Dukes staging of colorectal carcinoma stratifies prognosis based on depth of invasion and lymph node involvement. A surgical resection shows tumour invading through the full thickness of the muscularis propria into pericolorectal adipose tissue, with all 14 harvested lymph nodes free of tumour. What is the correct Dukes stage and approximate 5-year survival for this patient?
A
Dukes A — tumour confined within the muscularis propria; 5-year survival >90%
B
Dukes C — regional lymph node metastasis present; 5-year survival ~30–40%
C
Dukes B — tumour through the muscle wall, nodes negative; 5-year survival ~65–75%
✓
D
Dukes D — distant organ metastasis; 5-year survival <5%
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