Polyposis, hamartomatous intestinal

Polyposis, Hamartomatous Intestinal

Polyposis, hamartomatous intestinal, refers to a group of disorders characterized by the development of multiple hamartomatous polyps in the gastrointestinal tract. These polyps are benign, non-cancerous growths that arise from an abnormal mixture of tissue elements normally found at the site. Hamartomatous polyps are distinct from adenomatous polyps, which have a higher potential for malignant transformation.

Classification

Hamartomatous polyposis syndromes are classified based on their genetic and clinical features. The most common syndromes include:

• Peutz-Jeghers syndrome
• Juvenile polyposis syndrome
• Cowden syndrome
• Bannayan-Riley-Ruvalcaba syndrome

Pathophysiology

Hamartomatous polyps arise due to mutations in specific genes that regulate cell growth and differentiation. These mutations lead to the abnormal proliferation of cells, resulting in the formation of polyps. Each syndrome is associated with mutations in different genes:

• Peutz-Jeghers syndrome: Caused by mutations in the STK11 gene.
• Juvenile polyposis syndrome: Associated with mutations in the SMAD4 or BMPR1A genes.
• Cowden syndrome: Linked to mutations in the PTEN gene.
• Bannayan-Riley-Ruvalcaba syndrome: Also associated with PTEN mutations.

Clinical Features

The clinical presentation of hamartomatous polyposis varies depending on the syndrome:

• Peutz-Jeghers syndrome: Characterized by mucocutaneous pigmentation and gastrointestinal polyps, which can lead to intussusception and bleeding.
• Juvenile polyposis syndrome: Presents with multiple juvenile polyps, which can cause bleeding, anemia, and an increased risk of gastrointestinal cancer.
• Cowden syndrome: Features include multiple hamartomas, macrocephaly, and an increased risk of breast, thyroid, and endometrial cancers.
• Bannayan-Riley-Ruvalcaba syndrome: Characterized by macrocephaly, lipomas, and pigmented macules on the glans penis.

Diagnosis

Diagnosis of hamartomatous polyposis syndromes involves a combination of clinical evaluation, family history, and genetic testing. Endoscopic examination is used to identify and biopsy polyps. Genetic testing can confirm the diagnosis by identifying mutations in the associated genes.

Management

Management of hamartomatous polyposis syndromes includes regular surveillance and endoscopic removal of polyps to prevent complications such as bleeding and obstruction. Genetic counseling is recommended for affected individuals and their families. In some cases, prophylactic surgery may be considered to reduce cancer risk.

Prognosis

The prognosis for individuals with hamartomatous polyposis syndromes varies depending on the specific syndrome and the presence of associated complications. Regular monitoring and appropriate management can help mitigate risks and improve outcomes.

Also see

• Gastrointestinal polyps
• Hereditary cancer syndromes
• Genetic counseling