Villous adenoma

WikiDoc Resources for Villous adenoma
Articles
Most recent articles on Villous adenoma Most cited articles on Villous adenoma Review articles on Villous adenoma Articles on Villous adenoma in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Villous adenoma Images of Villous adenoma Photos of Villous adenoma Podcasts & MP3s on Villous adenoma Videos on Villous adenoma
Evidence Based Medicine
Cochrane Collaboration on Villous adenoma Bandolier on Villous adenoma TRIP on Villous adenoma
Clinical Trials
Ongoing Trials on Villous adenoma at Clinical Trials.gov Trial results on Villous adenoma Clinical Trials on Villous adenoma at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Villous adenoma NICE Guidance on Villous adenoma NHS PRODIGY Guidance FDA on Villous adenoma CDC on Villous adenoma
Books
Books on Villous adenoma
News
Villous adenoma in the news Be alerted to news on Villous adenoma News trends on Villous adenoma
Commentary
Blogs on Villous adenoma
Definitions
Definitions of Villous adenoma
Patient Resources / Community
Patient resources on Villous adenoma Discussion groups on Villous adenoma Patient Handouts on Villous adenoma Directions to Hospitals Treating Villous adenoma Risk calculators and risk factors for Villous adenoma
Healthcare Provider Resources
Symptoms of Villous adenoma Causes & Risk Factors for Villous adenoma Diagnostic studies for Villous adenoma Treatment of Villous adenoma
Continuing Medical Education (CME)
CME Programs on Villous adenoma
International
Villous adenoma en Espanol Villous adenoma en Francais
Business
Villous adenoma in the Marketplace Patents on Villous adenoma
Experimental / Informatics
List of terms related to Villous adenoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]

Synonyms and keywords: Adenomatous polyps; VA; TVA

Overview

Villous adenoma (also known as adenomatous polyp) is a type of polyp that grows in the colon and other places in the gastrointestinal tract. Villous adenomas may have a malignant (cancerous) transformation. Villous adenoma was first discovered by Helwig in 1946. Villous adenoma may be classified according to the World Health Organization into 3 groups: tubular, tubulovillous, and villous (most common). Villous adenoma arises from epithelial tissue, which is normally part of the lining of the colon. The estimated risk of malignancy among villous adenomas is between 15 and 25%. Genes associated in the development of villous adenoma, include: APC gene, TP53 gene, K-ras gene, and BAT-26 gene. The prevalence of villous adenoma is approximately 3.5 per 100,000 individuals worldwide. The most important risk factor in the development of villous adenoma is familiar syndromes (e.g. Turcot syndrome, juvenile polyposis syndrome, and Cowden disease). Surgical removal is the mainstay of therapy for villous adenoma. Cautery snare in conjunction with exploratory colonoscopy is the most common approach to the treatment of villous adenoma. Effective measures for the primary prevention of villous adenoma include periodical screening for patients with family history of familial adenomatous polyposis. According to the guidelines established by the American Cancer Society, individuals who reach the age of 50 should perform an occult blood test yearly.

Historical Perspective

• Villous adenoma was first discovered by Helwig in 1946.

Classification

• Villous adenoma may be classified according to the World Health Organization into 3 groups:

• Tubular,
• Tubulovillous
• Villous (most common)

Pathophysiology

• The pathogenesis of villous adenoma is characterized by:

• Villous adenoma arises from epithelial tissue with glandular characteristics
• Villous adenomas are considered pre-malignant lesions
• The estimated risk of malignancy among villous adenoma is between 15 and 25%

• Genes associated in the development of villous adenoma, include:

• APC gene
• TP53 gene
• K-ras gene
• BAT-26 gene

• On gross pathology, characteristic findings of villous adenoma, include:

• Polypoid or sessile mass
• Cauliflower-like in appearance

• On microscopic histopathological analysis, characteristic findings of villous adenoma, include:

• Nuclear changes at the surface of the mucosa
• Cigar-shaped (elongated) nucleus (usu. length:width > 3:1) with nuclear hyperchromasia
• Large round nuclei
• Nuclear crowding
• Positive Ki-67

Causes

• The most important cause of villous adenoma is familial adenomatous polyposis.

Differentiating Villous Adenoma from Other Diseases

• Villous adenoma must be differentiated from other diseases that cause abnormal growth of tissue projecting from a mucous membrane such as:

• Colorectal cancer
• Inflammatory fibroid polyp

Epidemiology and Demographics

• The prevalence of villous adenoma is approximately 3.5 per 100,000 individuals worldwide.
• The prevalence of adenomas increases with age.

Age

• Patients of all age groups may develop villous adenoma.

Gender

• Males are more commonly affected with villous adenoma than females.

Race

• Villous adenoma usually affects individuals of the Caucasian race.

Risk Factors

• Common risk factors in the development of villous adenoma, include:

• Familial adenomatous polyposis
• Peutz–Jeghers syndrome
• Turcot syndrome
• Juvenile polyposis syndrome
• Cowden disease
• Bannayan–Riley–Ruvalcaba syndrome (Bannayan-Zonana syndrome)
• Gardner's syndrome

Natural History, Complications and Prognosis

• The majority of patients with villous adenoma remain asymptomatic for years.
• Early clinical features include flatulence, bloating, and abdominal pain.
• If left untreated, patients with villous adenoma may progress to develop colorectal cancer.
• Common complications of villous adenoma, include:

• Bleeding
• Obstruction
• Bowel torsion

• Prognosis is generally good (if detected on time), and the 5-year mortality of patients with villous adenoma is approximately 89%

Diagnosis

Symptoms

• Villous adenoma is usually asymptomatic.
• Villous adenoma symptoms are often non-specific.
• Symptoms of villous adenoma may include the following:

• Flatulence
• Abdominal pain
• Constipation
• Diarrhea
• Cramping

Physical Examination

• Patients with villous adenoma usually are well-appearing.
• Villous adenoma physical examination is often non-specific.
• Physical examination may demonstrate:

• Rectal bleeding
• Rectal mass
• Pencil-thin stools

Laboratory Findings

• There are no specific laboratory findings associated with villous adenoma.

Imaging and Diagnostic Findings

• Colonoscopy is the imaging modality of choice for villous adenoma.
• On colonoscopy, characteristic findings of villous adenoma, include:

• A sessile polyp
• Size can range from 0.5 cm to 5 cm

• Other imaging studies include: computed tomographic colonography and video capsule endoscopy (less specific).

Treatment

Medical Therapy

• There is no treatment for villous adenoma; the mainstay of therapy is surgical removal.

Surgery

• Surgical removal is the mainstay of therapy for villous adenoma.
• Cautery snare in conjunction with exploratory colonoscopy is the most common approach to the treatment of villous adenoma.

Prevention

• Effective measures for the primary prevention of villous adenoma include periodical screening for patients with family history of familial adenomatous polyposis
• According to the guidelines established by the American Cancer Society, individuals who reach the age of 50 should perform an occult blood test yearly.
• Patients with villous adenoma are recommended to have flexible sigmoidoscopies once in 3 to 5 years to detect any abnormal growth which could be an adenomatous polyp.
• Once diagnosed and successfully treated, patients with villous adenoma are followed-up every 12 or 24 months.