Peritoneal Neoplasms

• • Most tumors affecting the peritoneum are secondary implants from intraperitoneal cancers (ovarian, gastric, pancreatic, etc)

  • Primary peritoneal tumors are derived from the mesodermal lining of the peritoneum

  • Patients usually present with advanced stages of disease

  • History of asbestos exposure in the case of malignant mesothelioma

Epidemiology

• • The most common peritoneal neoplasms include peritoneal mesothelioma and pseudomyxoma peritonei

  • Malignant mesothelioma occurs most commonly in men, with a long latent period (averaging 40 years) after prolonged asbestos exposure

  • Pleural malignant mesotheliomas outnumber peritoneal by 3:1

  • Pseudomyxoma peritonei is caused by a low-grade mucinous cystadenocarcinoma of the appendix or ovary that secretes large amounts of mucus-containing epithelial cells

Symptoms and Signs

• • Weight loss

  • Crampy abdominal pain

  • Large abdominal mass or distention due to ascites

  • Frequently intermittent or chronic small bowel obstruction

Laboratory Findings

• • Ascites cytologic studies for peritoneal mesothelioma rarely positive

  • Ascites cytologic studies for pseudomyxoma peritonei may demonstrate diagnostic mucus-containing epithelial cells

Imaging Findings

• • CT scans of the lower thorax and abdomen: Demonstrate pleural effusions, ascites, peritoneal and mesenteric thickening, and low-density soft-tissue masses involving the omentum and peritoneum

  • Malignant mesothelioma may have evidence of asbestos exposure on chest film as well pleural plaques on thoracic CT

  • In pseudomyxoma peritonei, US and CT scans show distinctive peritoneal scalloping of the liver margin and intra-abdominal calcified plaques

• • Chronic inflammatory peritonitis

  • Peritoneal mesothelioma

  • Cystic mesotheliomas

  • Well-differentiated papillary mesotheliomas

  • Pseudomyxoma peritonei

  • Benign appendiceal mucocele

  • Mesenteric cyst

  • Mesenteric lipodystrophy

  • Carcinomatosis

  • Abdominal lymphoma

Rule Out

• • Carcinomatosis

  • Chronic inflammatory peritonitis

• • Thorough history (including asbestos exposure) and physical exam

  • Abdominal pelvic CT scan to evaluate extent of lesion(s)

  • Chest film or thoracic CT scan to evaluate for metastatic disease

  • Diagnostic paracentesis: Lactic dehydrogenase (LDH) level, albumin, amylase, triglyceride level, WBC count, cytologic studies, Gram stain, and culture

  • Percutaneous biopsy of accessible peritoneal thickening vs diagnostic laparoscopy with biopsy

When to Admit

• • Symptoms seldom develop until advanced stages of disease, at which time patients have abdominal pain, distention, and frequently small bowel obstruction requiring admission

When to Refer

• • General surgeons instrumental in establishing the diagnosis, performing cytoreductive surgery, and administering intraperitoneal chemotherapy in conjunction with medical oncology

• • Palliative cytoreductive surgery: Gross tumor debulking and omentectomy (plus appendectomy and bilateral salpingo-oopherectomy in pseudomyxoma peritonei)

  • Intraperitoneal chemotherapy

  • Adjuvant intracavitary radiation

Surgery

Indications

• • Bowel obstruction

  • Malignant fistula formation

  • Palliation

Medications

• • Cisplatin/doxorubicin-based adjuvant chemotherapy ...