Peutz-Jeghers Syndrome

A rare cause of gastrointestinal polyposis that is mainly associated with benign skin lesions.


LKB1 is thought to be a tumour suppressor gene on chromosome 19. The exact function is not known but it is thought to regulate cell polarity. Loss of polarity is an important cytological feature of malignancy.

Clinical Features

Patients develop pigmented lesions is > 95% of cases, often in the lips (95%), oral cavity or hands. The lesiosn are usually flat, round and small (< 5 mm).
Gastrointestinal polyps are also very common, often in the small bowel where they can give rise to intrassusception. They also arise in the colon (2/3rds), the stomach and the rectum.
Patients most commonly come to attention due to gastrointestinal issues. Malignancies are very common (95% of patients by age 65), usually in the gastrointestinal tract (colon > stomach > small bowel) but also in the lung, breast and prostate, testis (Sertoli cell) and cervix.


Screening for gastrointestinal polyps is the most important aspect of screening:

  • Gastroscopy and colonoscopy at 8 years and 18 years; repeat every 3 years if polyps are detectet or after age 18; repeat every 2 years after age 50.
  • Small bowel pill cam at age 8 and 18 years (similar to above)

Regular testicular examination from a young age due to early onset of Sertoli cell tumours.
Regular pap smear from age 18.
Breast self examination and annual breast MRI from age 25-50.