Villous adenoma

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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.

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 adenoma are considered pre-malignant lesions

• The APC mutation has been associated with the development of villous adenoma, involving the [molecular pathway] pathway.
• 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:

• Cowden syndrome
• Peutz-Jeghers Polyp
• Inflammatory fibroid polyp

Epidemiology and Demographics

• The prevalence of villous adenoma is approximately [number or range] per 100,000 individuals worldwide.

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 are [risk factor 1], [risk factor 2], [risk factor 3], and [risk factor 4].

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

Other Diagnostic Studies

• Villous adenoma may also be diagnosed using colonoscopy.
• Findings on colonoscopy, include:

Treatment

Medical Therapy

• There is no treatment for villous adenoma; the mainstay of therapy is supportive care.

Surgery

• Surgery is the mainstay of therapy for villous adenoma.
• [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of villous adenoma.
• [Surgical procedure] can only be performed for patients with [disease stage] 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.