Basic Science Questions
Peutz-Jeghers Syndrome: Basic Science MCQs
1. What is the inheritance pattern of Peutz-Jeghers Syndrome?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked dominant
D) X-linked recessive
Answer: A) Autosomal dominant
Comments:
Peutz-Jeghers Syndrome follows an autosomal dominant inheritance pattern due to germline mutations in the STK11 (LKB1) tumor suppressor gene. Individuals with one mutated allele have a 50% chance of passing the condition to offspring (23, 24).
Incorrect Answers:
B) Autosomal recessive: Incorrect as PJS is not inherited through two defective alleles (23).
C) X-linked dominant: PJS is not related to sex-linked chromosomes (24).
D) X-linked recessive: PJS is an autosomal condition, not sex-linked (23).
2. Which gene mutation is responsible for Peutz-Jeghers Syndrome?
A) APC
B) STK11/LKB1
C) BRCA1
D) TP53
Answer: B) STK11/LKB1
Comments:
Peutz-Jeghers Syndrome is caused by germline mutations in the STK11/LKB1 tumor suppressor gene located on chromosome 19p13.3. This mutation leads to the disruption of cellular polarity, energy metabolism, and tumor suppression (23, 24).
Incorrect Answers:
A) APC: APC mutations are associated with familial adenomatous polyposis (FAP), not PJS (23).
C) BRCA1: BRCA1 mutations are linked to hereditary breast and ovarian cancer, not PJS (24).
D) TP53: TP53 mutations are seen in Li-Fraumeni syndrome, not PJS (23).
3. What is the penetrance of STK11 mutations in Peutz-Jeghers Syndrome?
A) Low (<20%)
B) Moderate (50%)
C) High (85-100%)
D) Variable based on environmental factors
Answer: C) High (85-100%)
Comments:
Nearly all individuals with pathogenic STK11 mutations develop clinical features of PJS, including gastrointestinal polyps and mucocutaneous pigmentation. Cancer risk penetrance approaches 85-90% (23, 24).
Incorrect Answers:
A) Low (<20%): Incorrect as STK11 mutations have a very high penetrance (23).
B) Moderate (50%): Incorrect; the penetrance is much higher, approaching 100% for clinical features (24).
D) Variable based on environmental factors: While environmental factors can modify cancer risk, they do not significantly alter the genetic penetrance of clinical features (23).
4. What nutritional factors contribute to the pathogenesis of Peutz-Jeghers polyps?
A) Iron deficiency
B) Vitamin D deficiency
C) Lack of dietary fiber
D) There are no known nutritional factors
Answer: D) There are no known nutritional factors
Comments:
Peutz-Jeghers polyps are hamartomatous lesions arising from a genetic defect in the STK11 gene. Nutritional deficiencies do not contribute to their development (24, 27).
Incorrect Answers:
A) Iron deficiency: While common in PJS due to chronic blood loss, it does not cause polyps (27).
B) Vitamin D deficiency: Not linked to hamartomatous polyp development (24).
C) Lack of dietary fiber: Does not play a role in the formation of hamartomatous polyps (23).
5. Which factors influence the high penetrance of cancer in Peutz-Jeghers Syndrome?
A) Loss of cell cycle regulation
B) Excessive epithelial proliferation
C) Disruption of cellular polarity and metabolism
D) All of the above
Answer: D) All of the above
Comments:
The high penetrance of cancer in PJS is due to the loss of STK11/LKB1 tumor suppressor function, leading to disrupted cell cycle regulation, unchecked epithelial proliferation, and impaired cellular polarity and metabolism (23, 27).
Incorrect Answers:
A) Loss of cell cycle regulation: Correct but incomplete; additional factors are involved (23).
B) Excessive epithelial proliferation: Correct but insufficient; this alone does not explain cancer risk (27).
C) Disruption of cellular polarity and metabolism: Correct but not the sole explanation for high penetrance (23).
Imaging and Radiology MCQs
6. What is the procedure of choice for detecting small bowel polyps in Peutz-Jeghers Syndrome?
A) CT enterography
B) MRI enterography
C) Capsule endoscopy
D) Small bowel follow-through (SBFT)
Answer: C) Capsule endoscopy
Comments:
Capsule endoscopy is considered the procedure of choice for detecting small bowel polyps in PJS, offering detailed mucosal visualization and sensitivity for even small polyps (33, 34).
Incorrect Answers:
A) CT enterography: Effective but involves ionizing radiation, making it less ideal for routine use (32).
B) MRI enterography: Excellent for detecting polyps but less sensitive for small mucosal lesions compared to capsule endoscopy (36).
D) SBFT: Useful for structural evaluation but inferior to capsule endoscopy for mucosal detection (33).
7. What is the characteristic appearance of intussusception on small bowel follow-through (SBFT) in PJS?
A) String of pearls
B) Coiled spring sign
C) Whirlpool sign
D) Target sign
Answer: B) Coiled spring sign
Comments:
The “coiled spring sign” is a classic finding on SBFT for intussusception, indicating the telescoping of bowel loops. It is a hallmark of intussusception caused by large polyps in PJS (31, 33).
Incorrect Answers:
A) String of pearls: Describes small bowel obstruction findings, unrelated to intussusception (33).
C) Whirlpool sign: Found in volvulus, not intussusception (33).
D) Target sign: A CT finding, not specific to SBFT (34).
8. What is the primary role of MRI in Peutz-Jeghers Syndrome?
A) Identification of extraintestinal manifestations
B) Detailed imaging of pancreatic abnormalities
C) Surveillance for small bowel polyps and complications
D) Screening for gynecological malignancies
Answer: C) Surveillance for small bowel polyps and complications
Comments:
MRI, particularly MRI enterography, is highly effective for non-invasive surveillance of small bowel polyps, identifying intussusception and other complications without ionizing radiation (34, 36).
Incorrect Answers:
A) Identification of extraintestinal manifestations: MRI is not routinely used for extraintestinal findings (36).
B) Detailed imaging of pancreatic abnormalities: Endoscopic ultrasound or dedicated pancreatic MRI is preferred (36).
D) Screening for gynecological malignancies: This is not a primary application of MRI in PJS (34).
9. What is the primary advantage of CT imaging in Peutz-Jeghers Syndrome?
A) Superior visualization of mucosal surfaces
B) Detection of metastatic disease
C) Identification of large bowel polyps
D) Detection of malignancies in the abdomen, including the pancreas, stomach, and colon
Answer: D) Detection of malignancies in the abdomen, including the pancreas, stomach, and colon
Comments:
CT imaging is particularly useful for identifying malignancies in the pancreas, stomach, and colon, which are common sites of cancer in Peutz-Jeghers Syndrome. It also aids in detecting intussusception and associated complications (24, 34).
Incorrect Answers:
A) Superior visualization of mucosal surfaces: This is better achieved with endoscopy or MRI (36).
B) Detection of metastatic disease: While CT can detect metastases, its primary role in PJS is identifying abdominal malignancies and complications (34).
C) Identification of large bowel polyps: Colonoscopy is the gold standard for detecting large bowel polyps (31).
10. What imaging modality is most effective in emergency settings for detecting intussusception in PJS?
A) MRI
B) CT
C) Ultrasound
D) Small bowel follow-through (SBFT)
Answer: C) Ultrasound
Comments:
Ultrasound is the preferred modality in emergencies for detecting intussusception. It is fast, widely available, and demonstrates the “coiled spring” sign characteristic of intussusception (31, 37).
Incorrect Answers:
A) MRI: Not suitable for emergency use due to longer acquisition times (36).
B) CT: Effective but involves radiation and is less available bedside (33).
D) SBFT: Not appropriate in acute settings due to preparation and time constraints (33).
MCQ Imaging and Radiology
11. What is the most common associated malignancy in Peutz-Jeghers Syndrome?
A) Colorectal cancer
B) Pancreatic cancer
C) Gastric cancer
D) Breast cancer
Answer: B) Pancreatic cancer
Comments:
Pancreatic cancer is one of the most significant malignancies associated with PJS, with a lifetime risk of 36%. Early detection using MRI or endoscopic ultrasound is critical (34, 36).
Incorrect Answers:
A) Colorectal cancer: Common in PJS, but the pancreatic cancer risk is higher (34).
C) Gastric cancer: Less frequent than pancreatic cancer in PJS (34).
D) Breast cancer: Increased risk in PJS, but it is not as strongly associated as pancreatic cancer (34).
12. What imaging modality is most effective in emergency settings for detecting intussusception in PJS?
A) MRI
B) CT
C) Ultrasound
D) Small bowel follow-through (SBFT)
Answer: C) Ultrasound
Comments:
Ultrasound is the preferred modality in emergencies for detecting intussusception. It is fast, widely available, and demonstrates the “coiled spring” sign characteristic of intussusception (31, 37).
Incorrect Answers:
A) MRI: Not suitable for emergency use due to longer acquisition times (36).
B) CT: Effective but involves radiation and is less accessible bedside (33).
D) SBFT: Not appropriate in acute settings due to preparation and time constraints (33).
13. What is the most common MRI finding in Peutz-Jeghers Syndrome?
A) Bowel wall thickening
B) Mucosal hyperenhancement
C) Polyps with lobulated margins
D) Target lesion
Answer: C) Polyps with lobulated margins
Comments:
MRI is highly effective for detecting small bowel polyps in PJS, which typically appear as lobulated soft-tissue masses on enterography (34, 36).
Incorrect Answers:
A) Bowel wall thickening: Common in inflammatory bowel disease, not characteristic of PJS (34).
B) Mucosal hyperenhancement: More typical of inflammation than hamartomatous polyps (36).
D) Target lesion: Refers to intussusception findings on CT, not polyp appearance (33).
14. What imaging modality is recommended for routine surveillance of small bowel polyps in PJS?
A) CT enterography
B) MRI enterography
C) Ultrasound
D) X-ray
Answer: B) MRI enterography
Comments:
MRI enterography is the preferred modality for routine surveillance due to its ability to provide detailed soft-tissue contrast without ionizing radiation, making it ideal for long-term follow-up (34, 36).
Incorrect Answers:
A) CT enterography: While effective, it exposes patients to ionizing radiation, limiting its use in routine surveillance (32).
C) Ultrasound: Not sufficient for comprehensive small bowel evaluation (31).
D) X-ray: Does not provide adequate detail for small bowel polyp surveillance (32).
15. What is the most common CT finding in small bowel intussusception in PJS?
A) Pneumatosis intestinalis
B) Target sign
C) Fat stranding
D) Bowel wall thickening
Answer: B) Target sign
Comments:
The “target sign” is a classic CT finding in intussusception, representing concentric layers of bowel telescoping into itself. It is commonly observed in PJS due to polyp-induced intussusception (33, 34).
Incorrect Answers:
A) Pneumatosis intestinalis: Rare finding, often related to ischemia, not common in PJS (33).
C) Fat stranding: Indicates inflammation but is not specific to intussusception (34).
D) Bowel wall thickening: Common in inflammatory bowel disease but not specific for intussusception (33).
MCQ Clinical Questions
16. What is the hallmark early clinical presentation of Peutz-Jeghers Syndrome?
A) Rectal bleeding
B) Mucocutaneous pigmentation
C) Small bowel obstruction
D) Iron-deficiency anemia
Answer: B) Mucocutaneous pigmentation
Comments:
Mucocutaneous pigmentation, particularly on the lips, buccal mucosa, and extremities, is often the earliest and most distinctive clinical feature of PJS. These macules typically appear in early childhood (41, 42).
Incorrect Answers:
A) Rectal bleeding: Common but generally presents later due to ulcerated polyps (42).
C) Small bowel obstruction: A later complication of large polyps or intussusception (44).
D) Iron-deficiency anemia: Secondary to chronic gastrointestinal bleeding, not an early feature (42).
17. What is the recommended age to begin routine cancer surveillance in children with Peutz-Jeghers Syndrome?
A) Age 5
B) Age 8-10
C) Age 15
D) Age 18
Answer: B) Age 8-10
Comments:
Cancer surveillance in PJS should start early, typically at age 8-10, with small bowel imaging (MRE or capsule endoscopy) and regular endoscopic evaluations to monitor for polyp development and potential malignancies (42, 44).
Incorrect Answers:
A) Age 5: Too early for routine cancer surveillance, as polyps typically develop later (42).
C) Age 15: Surveillance for polyps and cancer should begin before this age (42).
D) Age 18: Surveillance starting at this age may miss early-onset malignancies (41).
18. What is the lifetime risk of gastric cancer in Peutz-Jeghers Syndrome?
A) 5%
B) 15%
C) 29%
D) 50%
Answer: C) 29%
Comments:
The lifetime risk of gastric cancer in individuals with PJS is approximately 29%. This risk necessitates regular upper endoscopy as part of the surveillance program (42, 44).
Incorrect Answers:
A) 5%: Underestimates the risk, which is significantly higher (42).
B) 15%: Also underestimates the actual lifetime risk (42).
D) 50%: Overestimates the risk; while high, it does not approach this level (44).
19. Which cancer type has the highest lifetime risk in Peutz-Jeghers Syndrome?
A) Colorectal cancer
B) Pancreatic cancer
C) Gastric cancer
D) Breast cancer
Answer: A) Colorectal cancer
Comments:
Colorectal cancer has the highest lifetime risk in PJS, reaching approximately 39% by age 70. Pancreatic cancer (36%) and breast cancer (45-50% in females) are also significantly elevated (42, 44).
Incorrect Answers:
B) Pancreatic cancer: A major risk (36%), but less common than colorectal cancer (42).
C) Gastric cancer: Risk is lower (29%) compared to colorectal cancer (42).
D) Breast cancer: High in females (45-50%) but slightly lower in males (42).
20. What are the primary imaging methods for cancer surveillance in Peutz-Jeghers Syndrome?
A) CTE and PET/CT
B) Capsule endoscopy and MRE
C) Small bowel follow-through and ultrasound
D) PET/MRI and colonoscopy
Answer: B) Capsule endoscopy and MRE
Comments:
Capsule endoscopy and MR enterography (MRE) are the most effective imaging methods for small bowel surveillance, providing detailed mucosal visualization and identification of polyps and complications such as intussusception. MRE avoids ionizing radiation and is highly sensitive for bowel pathology (42, 44).
Incorrect Answers:
A) CTE and PET/CT: CTE involves radiation, and PET/CT is not routinely used for surveillance in PJS (41).
C) Small bowel follow-through and ultrasound: Less sensitive and specific compared to capsule endoscopy and MRE (33).
D) PET/MRI and colonoscopy: PET/MRI is not a routine modality for PJS surveillance (44).