Pseudomyxoma peritonei

Disease Summary: Benign colon tumor (Benign colon tumor)

1) Disease Description (Causes·Pathophysiology·Main Symptoms)

• Definition: A noncancerous (benign)-appearing mass (polyp, submucosal tumor, etc.) arising from the colonic mucosa or submucosal layer. These are classified as epithelial (adenomatous·hyperplastic·juvenile·inflammatory·Peutz-Jeghers, etc.) and non-epithelial (lipoma·carcinoid [neuroendocrine tumor]·leiomyoma·lymphangioma·deep cystic lesions, etc.).
• Causes/Pathophysiology: Develops due to abnormalities in the regulation of proliferation and differentiation of normal colonic epithelium. Environmental factors such as diet (high fat·high meat intake), insufficient fiber, smoking·alcohol consumption, and obesity increase the risk. Adenomatous polyps (adenomas) are precursor lesions in the pathway to cancer and may progress to adenocarcinoma over several years (typically 5–10 years) through the accumulation of cellular mutations.
• Main symptoms: Most are asymptomatic (incidentally discovered during screening). When symptoms occur, they may include bloody stool or mucus in the stool, rectal bleeding, and, rarely, abdominal pain·constipation·intestinal obstruction·intussusception caused by a large polyp.

2) Treatment Methods and Precautions

• Principle: In principle, discovered polyps are removed (resected) and a pathology examination is performed to rule out or eliminate the possibility of malignancy.
• Endoscopic treatment
  • Small polyps (≤5 mm): Removed using cold biopsy (cold biopsy forceps), etc.
  • Typical polyps (≤20 mm): Snare polypectomy.
  • EMR (endoscopic mucosal resection): The lesion is expanded by injecting normal saline or another substance into the submucosal layer and then removed en bloc (usually up to around 3 cm).
  • Piecemeal resection (piecemeal EMR): Large lesions are removed in sections.
  • ESD (endoscopic submucosal dissection): The submucosal layer is dissected to allow en bloc resection (considered for early cancer and large adenomas).
• Surgical treatment
  • Surgical resection (partial resection) is considered when complete endoscopic removal is impossible, when invasive cancer is present (high-risk findings on pathology), when complications occur (perforation, uncontrolled bleeding), or when deep invasion into the submucosa is suspected.
• Drug treatment: There are no cases in which the benign lesion itself is treated with medication. For inflammatory polyps, treatment of the underlying inflammatory bowel disease is important.
• Lifestyle management and prevention: Increase intake of fiber·fruits·vegetables, limit saturated fat·red meat·processed meat, maintain a normal weight, quit smoking·limit alcohol consumption.
• Precautions (self-care)
  • Visit a medical institution immediately if bleeding occurs after polyp removal (especially within 24 hours and over the following several days), or if abdominal pain, fever, large amounts of bloody stool, fever·severe pain occur.
  • If taking anticoagulants·antiplatelet drugs, prior consultation is necessary (medication adjustment is recommended before resection).

3) Outpatient Visit Checkpoints (Including Preparation Items·Example Questions)

• Preparation items
  • A record of all medications currently being taken (especially anticoagulants [warfarin, DOACs], aspirin/clopidogrel, etc.), including recent supplements·herbal medicines
  • Results of previous endoscopy·pathology examinations (previous polyp pathology reports), surgical history
  • Recent symptom records (the timing·frequency·characteristics of bloody stool·mucus·pain·changes, if present)
  • Family history (family history of colorectal cancer or adenomatous polyps)
• Items to confirm before an outpatient visit
  • Confirm the method of bowel preparation (taking a bowel cleanser·fasting) before the scheduled colonoscopy (screening)
  • Ask whether anticoagulants/antiplatelet drugs are being taken and whether they need to be stopped
• Example questions (phrases the patient can prepare in advance)
  • “I have had bloody stool for the past few days. Should I measure how severe it is?”
  • “When should I stop the medication I am taking (for example, aspirin) before the endoscopy?”

4) Examples of General Questions to Ask the Doctor

• “What does the pathology result of this polyp (or these polyps) mean? (Adenoma/hyperplastic/inflammatory, etc.)”
• “Does this polyp have a risk of progressing to cancer? How likely is recurrence?”
• “Which endoscopic resection method is recommended for this case? What is the likelihood of risks (bleeding·perforation)?”
• “What interval is recommended for follow-up monitoring (repeat examination)?”
• “Are there any specific recommendations for changes to my lifestyle or diet?”

5) Examples of Disease-Specific Questions

• “In the pathology report, which findings apply to the ‘adenoma (adenoma) — size · histologic type (tubular·villous) · dysplasia (low·high grade)’ categories, and what follow-up interval is recommended based on them?”
• “Was the polyp removed this time completely (R0), and if there is an abnormality at the resection margin (a positive margin), is additional treatment (additional resection/surgery) necessary?”

Additional Information (Summary)

• Risk of malignancy: Adenomatous polyps are precursor lesions of cancer. Size·number·histologic type (villous·adenomatous·high-grade dysplasia) are major risk factors (for example, the rate of malignant transformation is low for adenomas less than 1 cm, and increases at 2 cm or larger).
• Complications: Bleeding·perforation after resection; large polyps may cause intestinal obstruction·intussusception. Adenoma → possible progression to colorectal cancer (typically over an interval of several years).
• Departments: Gastroenterology (endoscopic examination and resection) / Colorectal Surgery (when surgical treatment is necessary).