Thin-walled cysts as a pathognomonic CT finding in cystic mesothelioma.

AIM: Cystic mesothelioma is a rare disease that results in abdominal distention and poorly defined abdominal pain. Diagnosis has always been made by tissue biopsy rather than by radiologic studies. MATERIALS AND METHODS: Our experience with 7 patients with cystic mesothelioma includes 4 patients who had not had prior surgery before the performance of a high resolution CT scan. A special review of the radiology of these cases was performed in order to identify any pathognomonic signs of this disease. RESULTS: In all patients who did not have a distortion of the radiologic images (as a result of surgical interventions) prior to the performance of a high resolution CT scan at our institution, a pathognomonic thin-wall cystic structure located within the gelatinous appearing mass was observed. These thin-walled cysts were of variable size and preferentially located within the greater omentum, pelvis and beneath the right hemidiaphragm. CONCLUSION: Cystic mesothelioma can be diagnosed preoperatively by a high resolution abdominal and pelvic CT. The thin-walled cysts with great variation in size are located beneath the right hemidiaphragm, within the greater omentum and in the pelvis. No other disease with these radiologic findings has been identified.

Prognostic indicators for patients undergoing cytoreductive surgery and perioperative intraperitoneal chemotherapy for diffuse malignant peritoneal mesothelioma.

BACKGROUND: This study evaluates clinical, radiological and histopathological prognostic indicators for survival of patients undergoing cytoreductive surgery and perioperative intraperitoneal chemotherapy for diffuse malignant peritoneal mesothelioma (DMPM). METHODS: Sixty-two consecutive patients with DMPM underwent cytoreduction and perioperative intraperitoneal chemotherapy at the Washington Cancer Institute. Twenty-six clinical, radiological and histopathological parameters were analyzed in univariate and multivariate analyses using overall survival as an endpoint. RESULTS: The overall survival was 79 months (range 1-143 months), with 1-, 3- and 5-year survival rates of 84%, 58% and 50%, respectively. The following 14 prognostic variables were significant for survival in the univariate analysis: gender (P = .045), peritoneal cancer index (P = .038), completeness of cytoreduction score (P = .010), interpretive CT findings of the small bowel and mesentery (P = .001), mesothelioma cell type (P < .001), mesothelioma nuclear size (P < .001), nuclear/cytoplasmic ratio (P < .001), mitotic count (P < .001), atypical mitosis (P < .001), chromatin pattern (P < .001), cellular necrosis (P < .001), perineural invasion (P = .037), stroma pattern (P < .001) and depth of invasion (P = .014). In the multivariate analysis, the only factor that was independently associated with an improved survival after cytoreduction and perioperative intraperitoneal chemotherapy was mesothelioma nuclear size. CONCLUSIONS: Mesothelioma nuclear size was the dominant factor determining overall survival in patients with DMPM. A histopathological staging system based on measurement of the nuclear size was proposed.

Computed tomographic characterization of malignant peritoneal mesothelioma.

AIMS AND BACKGROUND: Peritoneal mesothelioma is a rare disease with a universally fatal outcome when managed in a traditional palliative manner. New approaches to treatment using cytoreductive surgery and intraperitoneal chemotherapy suggest that long-term survival is possible in selected patients. Early recognition of this disease process with an orderly surgical approach will begin to optimize treatment. METHODS: Thirty-three patients with malignant peritoneal mesothelioma had CT scans available for review. A Z-score was used to evaluate the incidence of cancer at a particular anatomic site as compared to a general incidence of disease at all sites. CT was analyzed by abdominopelvic anatomic sites (16), abdominopelvic regions (9), and for presence versus absence of disease in the chest. Interpretative CT findings (class 0-III) were determined for these 33 patients. RESULTS: Eight of 33 patients had pleural abnormalities. In an analysis of 16 abdominopelvic anatomic sites, the vesical or rectal uterine pouch was involved in 97% and the greater omentum in 91%. These anatomic sites were the only ones with a positive Z-score of >1. In the analysis of 9 abdominopelvic regions, the central and pelvic regions had Z-scores >2 for large volume disease >5 cm. For CT interpretative findings class I, class II and class III was determined in approximately one-third in each category. Sixty-six percent of the patients had ascites by CT. CONCLUSIONS: Malignant peritoneal mesothelioma by CT evaluation predominates in tumor mass within the central and pelvic portions of the abdomen. Minimal, moderate, and extensive small bowel enlargements were seen in roughly one-third of the patients. With the use of the Z-score and interpretative small bowel findings a radiologic characterization of this disease for primary radiologic diagnosis is possible.