Peritoneal mesothelioma: CT, sonography, and gallium-67 scan

Imaging of Malignant Pleural, Pericardial, and Peritoneal Mesothelioma

Malignant mesothelioma is a rare tumor arising from the mesothelial cells that line the pleura, pericardium, peritoneum, and tunica vaginalis. Imaging plays a primary role in the diagnosis, staging, and management of malignant mesothelioma. Multimodality imaging, including radiography, computed tomography (CT), magnetic resonance imaging (MRI), and F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), is used in a variety of scenarios, including diagnosis, guidance for tissue sampling, staging, and reassessment of disease after therapy. CT is the primary imaging modality used in staging. MRI has superior contrast resolution compared with CT and can add value in terms of determining surgical resectability in equivocal cases. MRI can further assess the degree of local invasion, particularly into the mediastinum, chest wall, and diaphragm, for malignant pleural and pericardial mesotheliomas. FDG PET/CT plays a role in the diagnosis and staging of malignant pleural mesothelioma (MPM) and has been shown to be more accurate than CT, MRI, and PET alone in the staging of malignant pleural mesothelioma. PET/CT can also be used to target lesions for biopsy and to assess prognosis, treatment response, and tumor recurrence.

Malignant Peritoneal Mesothelioma

Background

The clinical characteristics of malignant peritoneal mesothelioma are not fully known, and it appears as a variable entity with different types of clinical presentation and with a difficult diagnosis.

Patients

Fifteen patients with malignant peritoneal mesothelioma were analyzed for asbestos exposure, clinical presentation, thrombocytosis, X-rays and echotomographic findings, peritoneal fluid cytology, surgical investigations, diagnosis in vita, therapy, cause of death, diagnosis time, and survival time.

Results

Asbestos exposure was present in 12 men. Abdominal pain, ascites, abdominal mass, weight loss and fever were the most common presentation symptoms. In 5 patients, the disease presented as a surgical emergency. Assembling the presenting symptoms, malignant peritoneal mesothelioma was subdivided in 3 types: classical (6 cases), surgical (5 cases) and medical (4 cases). Thrombocytosis was present in 11 cases. Peritoneal fluid cytology was positive for neoplastic mesothelial cells in 8 of 10 cases. Laparotomy (5 patients) and laparoscopy (7 cases) were diagnostic in all cases. Diagnosis in vita was malignant peritoneal mesothelioma for 13 patients, peritoneal carcinomatosis for 1, with only 1 autopsy diagnosis. Seven patients were treated with chemotherapy, showing a progression of the disease. Mean symptoms-to-diagnosis time was 122 days (4-410), and mean symptoms-to-survival time was 345 days (45-1510).

Conclusions

Malignant peritoneal mesothelioma is a very unusual disease characterized by a difficult diagnosis, a rapid evolution, a poor response to therapy, and a very high prevalence of thrombocytosis. A new clinical classification into three types (classical, surgical and medical) may be useful for a correct diagnosis. The early diagnosis of malignant peritoneal mesothelioma remains an important open question.

Radiology-pathology conference: primary peritoneal mesothelioma

Primary peritoneal mesothelioma is a rare neoplasm which carries a dismal prognosis. These highly aggressive tumors arise from mesothelial cells lining the peritoneum and are rapidly fatal. The neoplasm is typically associated with crocidolite asbestos exposure. We present the case of a 75-year-old man with primary peritoneal mesothelioma, with invasion into the right hepatic lobe.

Peritoneal mesothelioma: an unusual cause of an acute phase response presenting to the rheumatologist

The presence of an acute phase response may pre-date the eventual diagnosis of malignant disease by months or even years. We describe two patients referred to the rheumatology clinic, in which extensive investigation failed to identify an underlying cause to account for the presenting symptoms and an associated acute phase response. Several months later, repeated abdominal CT scans revealed an abnormality and subsequent laparoscopic biopsy confirmed a diagnosis of peritoneal mesothelioma.

US of the peritoneum

Familiarity with the pathophysiology of peritoneal disease is the basis of successful ultrasound (US) study of the peritoneum. The pouch of Douglas, diaphragmatic surfaces, the paracolic gutters, and the regions of the mesentery and omentum should receive careful scrutiny in the patient at risk for a peritoneal disease process. An optimal US technique requires assessment of the entire peritoneum with a transducer selected to reflect the depth of the region of interest. US may demonstrate minute quantities of free intraperitoneal fluid and is therefore capable of providing sensitive quantitative information about ascites. Qualitative information may also be inferred, as blood, pus, and neoplastic cells demonstrate correlation with particulate ascites on gray-scale US scans. Peritoneal nodules, plaques, and thickening may be detected on the visceral or parietal peritoneal surfaces, especially when high-frequency probes are used. Transvaginal study in women increases the sensitivity of US for detection of peritoneal disease. In women who have unexplained sepsis or are at risk for carcinomatosis, transvaginal scanning should routinely be added to the regular abdominal and pelvic studies regardless of the findings of those studies. Peritoneal carcinomatosis, primary peritoneal neoplasms, pseudomyxoma peritonei, and peritonitis have characteristic appearances at US.

Thallium-201 scintigraphy in malignant mesothelioma

A patient with malignant pleural mesothelioma was investigated using 201Tl scintigraphy. There was diffuse pleural tumour accumulation on planar scintigraphy. Single photon emission computed tomography (SPECT) demonstrated exact tumour location. It is concluded that planar scintigraphy using 201Tl may be useful in detecting mesothelioma. Clearer tumour localization is possible with SPECT.

Peritoneal mesothelioma: sonographic findings in nine cases

Ultrasonographic findings in nine cases of peritoneal mesothelioma are presented. The most common findings were sheet-like or nodular peritoneal thickening, soft tissue masses, fixation of the intestinal loops, mesenteric thickening, and minimal ascites which was disproportional to the degree of tumor dissemination. The authors found that abdominal sonography, using 3.75-7.5 MHz transducers, is a useful imaging method for diagnosis of peritoneal mesothelioma in high-risk groups.

Peritoneal mesothelioma simulating pseudomyxoma peritonei on CT and sonography

We present an unusual case of peritoneal mesothelioma with ultrasound (US) and computed tomographic (CT) features of scalloping of liver margins and ascitic septations mimicking pseudomyxoma peritonei. A brief review of the literature is also presented.

Peritoneal mesothelioma: hypertrophic gastroepiploic and omental arteries identified by radioimmune angiography

We report a first case of malignant peritoneal mesothelioma examined by radioimmune (RI) angiography with technetium-99m human serum albumin. The RI angiography clearly demonstrated the characteristic findings including hypertrophic gastroepiploic arteries and dilated omental branches. These findings may be very helpful in distinguishing malignant peritoneal mesotheliomas from peritoneal carcinomatosis.

Peritoneal mesothelioma: the role of computed tomography in diagnosis and follow up

Computed tomography (CT) was performed on 15 patients with proven peritoneal mesothelioma. Eight of these patients underwent follow-up CT. It was found that a discrete and measurable mass is unusual in comparison with the common occurrence of ascites and that therefore CT has little role in quantifying the disease. Ascites is usually a prominent feature. Other features (e.g. omental infiltration) were evaluated and these could be used to assess disease progression.

Radiological abnormalities among sheet-metal workers in the construction industry in the United States and Canada: relationship to asbestos exposure

We investigated the possible adverse health effects to sheet-metal workers who had past exposure to asbestos. A cross-sectional medical examination of 1,330 workers was conducted during 1986 and 1987 in seven cities in the United States and Canada. A total of 1,016 workers had been employed for at least 35 y in the industry, and the mean duration from onset of asbestos exposure was 39.5 y (SD = 7.41 y). Chest x-ray abnormalities were found in more than half of the group. Pleural fibrosis, the most frequently found abnormality, was present in 47.0% of the cases and was the only abnormality found in 27.8% of cases; parenchymal interstitial fibrosis, found in 33.1% of cases, was the only abnormality found in 16.2% of cases. Radiologic abnormalities increased as duration of exposure increased. A positive smoking history was associated with a higher prevalence of radiologically detectable parenchymal abnormalities, a finding confirmed by us and others. Dyspnea on exertion was graded by a Medical Research Council questionnaire, the examinee's self-assessment, and a more detailed 12-point scale questionnaire. Few persons had marked shortness of breath, and approximately one-third had slight dyspnea. Individuals who had radiologic abnormalities experienced more shortness of breath than did those who had no radiologic abnormalities. Cigarette smoking also resulted in a higher prevalence of dyspnea. The results indicate that during the past, construction sheet-metal workers have been significantly exposed to asbestos on the job. Every effort should be made to minimize the anticipated serious health consequences, and further asbestos exposure for those who continue in this trade should be avoided.

Gallium scanning in differentiating malignant from benign asbestos-related pleural disease

In order to assess the utility of 67gallium citrate in delineating malignant pleural mesothelioma from benign asbestos-related pleural disease, 49 patients with malignant mesothelioma and 16 with benign asbestos-related pleural disease were studied. Seven patients with malignant mesothelioma had no history of asbestos exposure, while the remaining 58 patients were exposed. Forty-three of the 49 patients (88%) with malignant mesothelioma had a positive 67gallium scan including 36 of the 42 (86%) patients with asbestos exposure and all 7 patients without a history of asbestos exposure. Three of 16 patients (19%) with benign asbestos-related pleural disease had a positive scan. 67Gallium radionuclide imaging is nonspecific but may be valuable in noninvasive monitoring of asbestos-exposed populations, which have a high risk for the late development of benign and/or malignant pleural disease.

The role of gallium-67 in the clinical evaluation of cancer

This review is based primarily on historic data, and it examines the indications for and limitations of gallium-67 scanning in the evaluation of patients with neoplasms. The use of gallium-67 scans is discussed according to tumor type, and data from the most representative and comprehensive studies are included. The results described, some of which were obtained primarily with older imaging techniques, should be regarded as representing the minimum that can be expected from application of this imaging procedure.