Small bowel neoplasms

Epidemiology:

• Primary tumours of the small bowel are relatively uncommon
• Account for 5% of GI neoplasms
• May be benign or malignant
• Commonest benign tumours are leiomyomas (smooth muscle tumours)

There are 4 factors associated with small bowel malignancies:

• Developmental disorders
• Immunocompromisation
• Geographical location
• Crohn’s disease

Developmental disorders:

• Polyposis coli
• Peutz-Jegher syndrome: An ill-understood inherited relationship between intestinal polyps mainly in the jejunum and marginal pigmentation around the buccal and anal mucosa – the usual presentation is with intussusception
• Gardner’s syndrome: A rare disorder in which small bowel adenomas and carcinomas are associated with skeletal abnormalities and desmoid tumours

Immunocompromisation:

• Coeliac disease
• Acquired immunodeficiency (e.g. AIDS)
• Immunosuppression (chiefly in transplant pts) is associated with small bowel lymphomas

Geographical location:

Lymphomas are more common in the Middle East than elsewhere.

Benign tumours – pathological features:

Are commoner in the duodenum

Progression to carcinoma can occur

Are three main types:

• Leiomyomas
• Lipomas (more common in the large bowel)
• Neurofibromas

Malignant tumours:

Are, again, three main types:

• Lymphomas
• Adenocarcinomas (most common in the duodenum)
• Secondary tumours (rare, but occur in lung and breast cancer)