Peutz-Jeghers syndrome

Definition

Peutz-Jeghers syndrome (PJS) is a rare familial cancer syndrome that causes intestinal polyps, skin freckling, and an increased risk for cancer.

Description

Peutz-Jeghers syndrome affects both males and females. The characteristic, or pathognomonic, features of PJS are unusual skin freckling and multiple polyps of the small intestine. The skin freckles, which are bluish to brown to black in color, can be found on the lips, inside the mouth, around the eyes, on the hands and feet, and on the genitals. The freckles are called benign hyperpigmented macules and do not become cancerous. The polyps in PJS are called hamartomatous polyps, and are found in the small intestine, small bowel, stomach, colon, and sometimes in the nose or bladder. Hamartomatous polyps are usually benign (not cancerous), but occasionally become malignant (cancerous). Dozens to thousands of hamartomatous polyps may develop. A person with PJS with benign hamartomatous polyps can have abdominal pain, blood in the stool, or complications such as colon obstruction or intussusception (a condition in which one portion of the intestine telescopes into another). Surgery may be required to remove the affected part of the colon. A person with PJS is at increased risk for cancer of the colon, small intestine, stomach and pancreas. Women with PJS are also at increased risk for breast and cervical cancer, and a specific type of benign ovarian tumor called SCTAT (sex cord tumors with annular tubules). Men with PJS are also at increased risk for benign testicular tumors.

Diagnosis

The diagnosis of Peutz-Jehgers syndrome can be made clinically in a person with the characteristic freckles and at least two hamartomatous polyps. A pathologist needs to confirm that the polyps are hamartomatous instead of another type of polyp. If a person has a family history of PJS, the diagnosis can be made in a person who has either freckles or hamartomatous polyps. When someone is the first person in his/her family to be diagnosed with PJS, it is important for all first-degree relatives to be carefully examined for clinical signs of PJS. About half of all persons with PJS will have family members with symptoms of PJS. Symptoms can vary between families and between members of the same family. Some family members may just have freckling and others may have more serious medical problems such as bowel obstruction or cancer diagnosis. The freckles in PJS usually appear in childhood and fade as a person gets older, so it may be necessary to look at childhood photos in an adult who is being examined for signs of PJS.

Risks

Hamartomatous polyps may be diagnosed from early childhood to later in adulthood. On average, a person with PJS develops polyps by his/her early 20s. The lifetime risk for cancer is greatly increased over the general population, and cancer may occur at an earlier age. Early and regular screening is important to try to detect any cancers at an early stage. The benign ovarian tumors in women with PJS may cause early and irregular menstruation. The benign testicular tumors in men may cause earlier growth spurts and gynecomastia (development of the male breasts).

Causes

PJS is a genetic disease caused by a mutation of a tumor suppressor gene called LBK1 (or STK11) on chromosome 19. The exact function of LBK1 is unknown at this time. PJS is inherited as an autosomal dominant condition, which means that a person with PJS has a 50% chance of passing it on to each of his/her children. Screening and/or genetic testing of family members can help sort out who has PJS or who is at risk for developing PJS. Identification of a person with PJS in a family may result in other family members with more mild symptoms being diagnosed, and then receiving appropriate screening and medical care.

Genetic Testing

Fifty percent of people clinically diagnosed with PJS will have a mutation in the LBK1/STK11 gene detected in the lab. The other half will not have a detectable mutation at that time, but may have other PJS-causing genetic mutations discovered in the future. In families where a mutation is known, family members can be tested for the same mutation. A person who tests positive for the family mutation will be diagnosed with PJS (even if he/she does not currently show signs of PJS), will need to have the recommended screening evaluations, and is able to pass on the mutation to his/her children. A person who tests negative for a known family mutation will be spared from screening, and his/her children will not be at risk for PJS. When the mutation cannot be found in a family, genetic testing is not useful, and all persons at risk for inheriting PJS will need to have screening for PJS throughout their life span.

Screening and Treatment

Regular medical examinations and special screening tests are needed in people with PJS. The age at which screening begins and the frequency of the tests is best determined by a physician familiar with PJS. Screening schedules depend on symptoms and family history. Colonoscopy, used to search for polyps in the colon, usually begins in adolescence. X rays and/or upper gastrointestinal endoscopy are used to screen for polyps in the stomach and small intestine. The goal of screening is to remove polyps before they cause symptoms or become cancerous. Surgery may be necessary. Females with PJS need to have annual gynecologic examinations by age 18, and breast mammography starting between the ages of 25 and 35. Males with PJS need to have annual testicular examinations. If a person with PJS develops cancer, it is treated as it would be in the general population.

KEY TERMS

Gynecomastia

Overdevelopment of the mammary glands in males; male breast development.

Intussusception

The folding of one segment of the intestine into another segment of the intestine.

Pathognomonic

Characteristic of a disease; a pattern of symptoms not found in any other condition.

Polyp

A mushroom-like growth that may be a precursor to cancer.