Unusually Aggressive Presentation of Malignant Peritoneal Mesothelioma: Two Case Reports.

Malignant peritoneal mesothelioma is a rare disease. Patients mainly present with abdominal distension, pain, nausea, and weight loss with or without an exposure history of asbestos. Diagnosis may be difficult from a clinical and histopathologic perspective. Treatment options are surgery in early stages, radiotherapy and/or intraperitoneal or systemic therapy. Prognosis depends on TNM stage and histologic subtype with epithelioid subtype being the most favorable one but in general remains poor. We present a 59-year-old male (patient 1) and a 79-year-old female (patient 2) with progressive dyspnea. PET-CT of patient 1 revealed metastatic spread in the pleura and extensive peritoneal carcinomatosis. PET-CT of patient 2 displayed FDG-avid lymph nodes on both sides of the diaphragm, polyserositis, and FDG uptake along the peritoneum. Both patients were eventually diagnosed with malignant peritoneal mesothelioma. Patient 1 was treated with carboplatin and gemcitabine, and patient 2 received no systemic therapy. Even though the epithelioid subtype was found, both patients succumbed due to rapid tumor progression in a matter of a few weeks only. Presentation with polyserositis even in the absence of relevant asbestos exposure may represent malignant peritoneal mesothelioma if ascites is present, and rapid invasive diagnostic (excision biopsy) should be performed. These two unusual cases emphasize that even in epithelioid subtype, clinicians ought to be aware of possible rapid clinical deterioration, and timely diagnosis with initiation of therapy is crucial. Further research is necessary to better understand tumor biology, establish predictive markers, and develop new treatment options.