Peritoneal Mesothelioma

Key Points:

Nature: Most common primary malignant neoplasm of the peritoneum, characterized by mesothelioma.
Histologic Subtypes:
- Epithelioid (most common and best prognosis).
- Sarcomatoid.
- Biphasic.

Epidemiology:

Approximately 800 new cases diagnosed per year in the U.S.
Similar frequency in men and women.
Median age at presentation: 50 years.

Risk Factors:

Asbestos exposure in about one-third of patients, with a significant association between asbestos exposure and pleural mesothelioma.

Clinical Presentation:

Involvement of all peritoneal surfaces, presenting with hard, white masses, and plaques.
Associated with local invasion of intraabdominal organs.
Symptoms include abdominal pain, weight loss, and ascites.

Diagnosis:

Imaging shows mesenteric thickening, peritoneal studding, and ascites.
Image-guided core needle biopsy or diagnostic laparoscopy often required.

Treatment:

Combined-modality approach with cytoreductive surgery and HIPEC improves survival.
Median survival rates: 30 to 60 months with this treatment.
Factors associated with better outcomes:
- Complete or near-complete cytoreduction.
- Low histologic tumor grade.
- Epithelioid histology.
- Use of cisplatin for HIPEC.

Prognosis and Complications:

5-year survival rate: 42% if complete cytoreduction is achieved.
Postoperative mortality rate is 2% to 3%, with 20% to 40% of patients reporting complications.
Systemic chemotherapy (cisplatin and pemetrexed) offers modest benefits and is used palliatively.

Comprehensive Summary: Peritoneal mesothelioma is a serious malignancy of the peritoneum with a challenging prognosis. It most commonly presents in the fifth decade of life without a strong gender predilection. Asbestos exposure remains a significant risk factor. Clinically, it is characterized by diffuse peritoneal involvement, and diagnostically, it often requires invasive procedures. The current treatment strategy emphasizes aggressive surgery combined with HIPEC, offering improved survival chances particularly in patients with favorable histologic features. Despite advances in treatment, the potential for postoperative complications is substantial, necessitating the consideration of systemic chemotherapy for inoperable cases. The importance of histologic grade and type in the prognosis underlines the need for precise diagnostic and therapeutic approaches.