Papillary mesothelioma of the peritoneum in the absence of asbestos exposure

BACKGROUND: Malignant mesothelioma of the peritoneum is a very rare neoplasm, commonly associated with asbestos exposure and often rapidly fatal. Well Differentiated Papillary Mesothelioma of the Peritoneum (WDPMP) is regarded as a less aggressive variety of the tumor. Progressive ascites is often the only clinical manifestation of the disease and differentiation of WDPMP from benign mesothelial hyperplasia or adenocarcinoma is difficult. PATIENTS AND METHODS: Here we report the case of a 45-year-old patient who presented with ascites but without evidence of portal hypertension, liver disease or abdominal malignancy. On diagnostic laparoscopy small tumor nodules were found to cover the parietal peritoneum and the greater omentum and histopathologically corresponded to papillary mesothelial hyperplasia with minimal nuclear atypia. Histochemically biopsies were positive for Calretinin, Cytokeratins and Epithelial Membrane Antigen (EMA). Based on these findings the diagnosis of WDPMP was made and the patient was closely followed without primary cytostatic therapy. CONCLUSIONS: Progressive ascites was the only clinical symptom in this patient, while liver disease, portal hypertension and gastrointestinal malignancies were ruled out by clinical, laboratory and imaging techniques. Laparoscopic biopsy revealed WDPMP to be the underlying disease. Immunocytochemistry is required to establish the diagnosis of this rare malignant disorder which is even more uncommon in the absence of a history of asbestos exposure. Due to the indolent course of WDPMP therapy should only be initiated when signs of rapid tumor progression become apparent.