CASE 9516 Published on 09.08.2011

Peritoneal malignant mesothelioma (MPM)


Abdominal imaging

Case Type

Clinical Cases


Drevelegas K, Potsi S, Chourmouzi D, Emanouilides C, Papalavrentios L, Stoikou I, Markou A, Drevelegas A

Interbalkan Medical Center,
Asklipiou, Pylaia 57001,
Thessaloniki, Greece

68 years, female

Area of Interest Abdomen, Thorax ; Imaging Technique CT
Clinical History
A 68-year-old woman presented with back pain and abdominal swelling over the preceding four months. The patient appeared feeble, dehydrated with an ECOG performance status of 3 and with palpable abdominal wall masses.
Past medical history includes breast cancer (stage-II), diagnosed 22 years earlier, treated with CMF and radiation.
Imaging Findings
Abdominal CT showed a large ascites, and irregular soft-tissue infiltration of the omentum (omental cake) with heterogeneous enhancement. Localised ascitic fluid presented at the right subhepatic space and the rectovaginal space. Diffuse peritoneal thickening with several peritoneal implants as well as liver metastases were noted in segments II, VI, and VIII (Fig. 1a, b, c).
A chest CT demonstrated neither focal pleural masses nor pleural effusions.
CT-guided biopsy of a peritoneal implant disclosed the presence of peritoneal mesothelioma. Malignant cells stained positive for CK 7, calretin and were negative for CK 20 or CEA. In November 2008 the patient was started on chemotherapy. Upon first radiologic assessment, there was substantial improvement (Fig. 2a, b, c). In October 2009, CT evaluation showed regrowth of the disease (Fig. 3a, b) and her treatment was changed, resulting in moderate radiological improvement (Fig. 4a, b). Throughout the treatment period, her clinical condition gradually improved.
Malignant mesothelioma is an uncommon malignant neoplasm that arises from mesothelial cells or multipotential subserosal mesenchymal cells of the pleura, peritoneum, pericardium, or tunica vaginalis of the testis. The majority of malignant mesotheliomas originate in the pleura. Peritoneal primary mesotheliomas account for 6%–10% of malignant mesotheliomas [1]. This primary abdominal tumour is usually an aggressive and rapidly spreading neoplasm. It occurs most commonly in older men and it has a strong association with high levels of asbestos exposure [2, 3, 4].
Malignant peritoneal mesothelioma has non-specific radiological abnormalities. Ultrasonography will reveal ascitic fluid and intra-abdominal masses, whereas CT appearances may vary. According to Pickhardt et al, the CT features of MPM’s range from a "dry" appearance, consisting of peritoneum-based masses, to a "wet" appearance, consisting of ascites, irregular or nodular peritoneal thickening, and an omental mass . Scalloping or direct invasion of adjacent abdominal organs may also be seen. Associated calcified plaques are uncommon in malignant peritoneal mesotheliomas in contrast to the pleural counterpart [5].
Several investigators have reported that MPM occurs in two gross forms. The focal form manifests as a large mass, usually in the upper abdomen, along with scattered peritoneal nodules. It may extend into adjacent organs, but typically it does not spread diffusely throughout the peritoneal cavity, similar to our case.
The diffuse or desmoplastic form manifests as diffuse as infiltrating and thickening the peritoneum in a sheet-like fashion. This form tends to spread along the serosal surfaces, may invade the retroperitoneum, extend into the abdominal wall, and grow through the diaphragm into the pleural cavity, thus encasing both solid and hollow visceral organs. The amount of ascites varies, but massive ascites is uncommon [3, 6, 7].
Diffuse malignant mesotheliomas are highly aggressive and most of them are incurable. In contrast, patients with localised malignant mesotheliomas usually have a good prognosis, especially after complete surgical excision of the lesions [8].
The treatment of MPM may involve both surgery and systemical chemotherapy.
According to Jeonf et al, the diagnosis of malignant peritoneal mesothelioma is strongly suggested if there is concomitant asbestos-related pleural and lung parenchymal disease such as pleural plaque [9]. In our case there was neither history of asbestos exposure nor focal pleural masses.
As imaging findings are non-specific the histological and immunohistochemical tests are needed for diagnostic accuracy. Although the prognosis is usually poor, a subset of patients may enjoy a prolonged survival.
Differential Diagnosis List
Peritoneal malignant mesothelioma (MPM)
Metastatic peritoneal carcinomatosis
Primary peritoneal serous carcinoma
Tuberculous peritonitis
Inflammatory diseases of the mesentery
Final Diagnosis
Peritoneal malignant mesothelioma (MPM)
Case information
DOI: 10.1594/EURORAD/CASE.9516
ISSN: 1563-4086