Introduction

Tubular Adenoma: Tubular adenomas are benign epithelial neoplasms of the colon and rectum that arise from glandular tissue and have the potential to progress to colorectal cancer if left untreated. Tubular adenomas are embedded in the lamina propria. The terms ‘tubular adenoma’, ‘tubulovillous adenoma’ and ‘villous adenoma’ all refer to the microscopic architecture of the tumour. The probability of malignancy depends upon the villous component of the tumour.¹

Characteristics

• Location: can occur anywhere in the colon, but is most common in the rectosigmoid region
• Size: usually small ( <1cm), but larger adenomas have a higher risk of cancerous transformation
• Dysplasia: shows low or high-grade dysplasia, which indicates their malignant potential 
• Histology: composed predominantly of tightly packed, branching tubular glands²

What are the histopathological features of tubular adenoma?

Pathologists assess the following features to determine the severity of the polyps.

As there is an Increased number of glands 

• Enlarged epithelium 
• Dark staining of nuclei
• Cellular atypia and degree of dysplasia²

Aetiology 

Community-based estimates reveal an increased prevalence with age and male gender.

• Higher risk of colon cancer in patients with a first-degree relative
• Family history 
• Smoking 
• Excess alcohol intake 
• Diabetes mellitus 
• High body mass index 
• Low fibre diet 
• Limited physical activity

Tubular adenoma symptoms

Most adenomas don't cause symptoms, so you may not know you have tubular adenomas until your doctor finds them during a colonoscopy.⁶ Tubular adenomas are uncommon in children but can occur often in association with polyposis syndromes, e.g familial adenomatous polyposis.

• Bleeding from the rectum
• Diarrhoea
• Constipation 
• Change in bowel habits.
• Gastrointestinal bleeding 
• Mucus in faeces
• Frequent diarrhoea and constipation 
• Abdominal cramps 
• Anaemia

Adenomatous polyposis syndromes

People with these syndromes develop adenomatous polyps, which are classified based on their shape, size, and appearance under a microscope. Adenomatous polyps are usually benign( noncancerous), though they can be cancerous.

Familial adenomatous polyposis ( FAP) 

This is the most common inherited polyposis syndrome, which has hundreds of colorectal adenomatous polyps. It is a rare condition with a significant risk of Cancer and Comorbidity. FAP uniformly involves the large bowel, and it may also produce lesions in the stomach and upper intestinal tracts. This hereditary syndrome is identified by numerous polyps in the colon and sometimes other parts of the gastrointestinal tract. Familial adenomatous polyposis results from germline adenomatous polyposis coli (APC) gene mutations, and many affected patients die from colorectal cancers, which arise from colorectal polyps. Genetic testing may be of help in the diagnosis of adenomatous polyposis cases and the clinical management of affected individuals.⁷

Types of polyposis syndromes

Juvenile polyposis syndromes 

Juvenile polyposis syndrome ( JPS) is a rare disorder characterised by multiple juvenile polyps in the gastrointestinal tract and germline mutations in SMAD4 or BMPR1A. It is inherited in an autosomal dominant manner, and 20 -50 % of cases have a positive family history. Polyps occur most commonly in the distal colon but sometimes also in the small bowel. Symptoms include acute or chronic blood loss, mucus discharge, diarrhoea, intussusception or rectal prolapse and protein-losing enteropathy.⁴

Peutz-Jeghers syndrome ( PJS)

This is a very rare genetic condition characterised by the development of benign polyps in the stomach and intestines and by the distinctive spots of dark blue to dark brown skin freckling around the mouth, eyes, nostrils, fingers, oral mucosa, perianal area, and toes. The most common symptom is recurrent colicky abdominal pain caused by obstruction or intussusception. PJS is associated with a significantly increased risk of both intestinal and extraintestinal cancer. Multiple hamartomatous polyps in the gastrointestinal tracts are the hallmarks of PJS. Mostly, gastrointestinal polyps are found in the small intestine. They can be found in the stomach and the large intestine.³

Diagnosis 

• Colonoscopy: A Flexible tube is inserted into the rectum to inspect the rectum and sigmoid. Once polyps are found in your colon, you need to have an annual colonoscopy until you have surgery to remove the polyps⁶
• Histopathology: Histopathologically, the polyps are classified as hamartomatous, inflammatory, juvenile, adenomatous, with or without dysplasia and malignant polyps. Juvenile polyps are seen in pediatric populations. The risk of cancer development is highest in villous adenomas. The histological grading of adenomas is defined using a two-tiered system that subdivides the lesions into low-grade dysplasia ( LGD) and high-grade dysplasia (HGD). High-grade dysplasia is characterised by marked complex glandular crowding and irregularity of glands with cribriform architecture and intraluminal necrosis⁵
• Genetic Testing: A simple blood test can determine if you carry the abnormal gene that causes FAP. Genetic testing may also detect whether you are at risk of FAP. Ruling out FAP spares for at-risk children with years of screening and emotional distress. Genetic screening in patients born with hereditary polyposis syndrome is recommended to begin around puberty, before the initiation of endoscopic screening⁵
• Faecal occult blood test - may detect early bleeding
• Imaging ( MRI /CT)-If there are concerns about syndrome associations or complications

Management 

Endoscopic polypectomy

• Isolated tubular adenomas 
• Complete resection and histologic evaluation.

Surveillance

• Genetic testing for the APC gene mutation is one of the screening strategies for FAP. Individuals with family history of FAP should undergo genetic counselling and screening for FAP for ages 10 and 12 years to identify carriers of APC gene mutation⁵
• Follow-up colonoscopy depends on risk factors
• Low-risk adenomas (low-grade dysplasia, follow-up in 3-5yrs)
• High-risk adenomas(>10mm,villous features, high grade dysplasia)

Surgical intervention

• It is required if there are multiple adenomas, high-grade dysplasia, or an underlying genetic syndrome⁸
• Colectomy is considered for conditions like FAP to prevent colorectal cancer

Genetic counselling

It is recommended for children with multiple adenomas and for individuals with characteristic features or a family history of polyposis syndromes to optimise surveillance, guide management and support affected families.⁹ Genetic counselling is recommended for:

• A family history of polyposis syndromes
• Presence of extracolonic manifestations
• Individuals with extraintestinal manifestations

FAQs

How do I reduce the risk of tubular adenomas?

Reduce fat intake and increase physical activity.¹⁰

Can I prevent tubular adenomas?

Yes, by adopting a healthy lifestyle.¹⁰

• Regular exercise
• Maintaining a healthy weight
• Routine screening
• Limit processed foods and meat

How often should I have a colonoscopy after a tubular adenoma is removed?

• Low-risk adenoma - 3-5 years 
• High-risk adenomas - 1-3 years

Can tubular adenomas recur?

The risk of Tubular Adenoma is low, but increases if the Adenoma is large or if the patient is over 50. Follow-ups are recommended.¹⁰

How long does it take to recover from a colonoscopy?

It should take 30-45 mins to have your colonoscopy, you may also have blood in your faeces or bleeding from your bottom, for a couple of days.

Do tubular adenomas always turn into cancer?

They have the potential to become colorectal cancer if left untreated.

Where are the adenomatous polyps in children located?

In children, adenomatous polyps are often solitary and located in the rectosigmoid.

Summary

Tubular adenoma is a benign tumour that is not life-threatening, though its size and location can make it potentially dangerous. Classified as low risk if small with low-grade dysplasia. Risk increases with size, villous features and high-grade dysplasia. It can progress to adenocarcinoma via the adenocarcinoma sequence. Diagnosis is essential as tubular adenomas can severely affect bowel movements. Colonoscopy is a valuable tool for detecting and removing polyps. Early detection of tubular adenoma is crucial as it can significantly reduce the risk of cancer development. Polyposis syndromes are a group of inherited disorders characterised by the development of multiple polyps in the gastrointestinal tract.