|Year : 2012 | Volume
| Issue : 1 | Page : 41-43
A case of multicystic peritoneal mesothelioma
Koyye R Tagore1, Ramineni S. A. Kumar1, N Bhavani2, S Ramachander3
1 Department of Pathology, MNR Medical College, Sangareddy, Andhra Pradesh, India
2 Department of Gynaecology and Obstetrics, MNR Medical College, Sangareddy, Andhra Pradesh, India
3 Department of Surgery, MNR Medical College, Sangareddy, Andhra Pradesh, India
|Date of Web Publication||28-Aug-2012|
Koyye R Tagore
Department of Pathology, MNR Medical College, Narasapur Road, Sangareddy, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Multicystic peritoneal mesothelioma is an unusual mesothelial lesion that deserves separate consideration because of its characteristic histologic picture and its benign behavior. In the past, this lesion was often confused with cystic lymphangioma, mesenteric lymphatic cyst, diffuse mesothelioma, and disseminated form of mucin-producing adenocarcinoma. Diagnostic accuracy and long-term follow-up are needed due to high incidence of recurrence. We report a rare case of huge multicystic peritoneal mesothelioma in a 36-year-old woman. At follow-up 18 months after surgery, the patient remained asymptomatic with no further growth.
Keywords: Multicystic, mesothelioma, peritoneum
|How to cite this article:|
Tagore KR, Kumar RS, Bhavani N, Ramachander S. A case of multicystic peritoneal mesothelioma. Ann Nigerian Med 2012;6:41-3
| Introduction|| |
Multicystic peritoneal mesothelioma commonly occurs in young to middle-aged women (mean age, 37 years) and female to male ratio is 5:1. However, cases involving men, preadolescent children,  elderly women  and rare extra-abdominal cases have been reported.  It is usually brought to notice because it produces vague lower abdominal pain or symptoms suggesting partial intestinal obstruction, such as distension, nausea, or vomiting. Rarely, patients present with an acute abdomen  or ascites.  The symptoms of the disease are relatively non-specific, and a correct preoperative diagnosis is difficult.
| Case Report|| |
A 36-year-old female presented with breathlessness on mild exertion and swelling in the right lower abdomen for 1 month. On examination, she was afebrile with moderate pallor and vital signs were normal. There was mild pedal edema. Cardiovascular and chest examination were normal. Abdominal examination revealed a mass of 26 weeks size which was smooth and cystic with palpable lower boarder. Vaginal examination showed a normal sized uterus and the fornices were free. Routine investigations were within normal limits except for moderate microcytic hypochromic anemia with hemoglobin of 8.5 g/dl. Ultrasonography showed a large, lobulated multicystic mass extending into the pelvis and attached to the peritoneal surface of the right lower abdomen. Needle aspiration yielded pale yellow fluid which showed mesothelial cells on cytology. At laparotomy the multicystic mass was found to occupy almost the entire abdomen and was adherent to the small bowel, large bowel, liver, and bladder. The tumor was resected except where it was inseparable from the viscera. The patient made an uneventful postoperative recovery.
Grossly the mass measured 250 ×180 × 130 mm and weighed 5.8 kg. On cut section, it was multicystic with numerous thin walled translucent cysts [Figure 1] and [Figure 2]. The cysts are 0.5-5 cm in diameter with a thin translucent wall and slightly gelatinous clear content. In between the cysts, fibrous tissue was present. Microscopic examination revealed multiple cystic spaces lined by flat to low cuboidal cells, with occasional hobnail cell features and no atypia or mitoses. The cysts were separated by fibrous septa with areas of acute and chronic inflammation and slight stromal cell proliferation [Figure 3]. The cells lining the cysts stained positive for cytokeratin and calretinin markers on immunohistochemical stains. A diagnosis of benign multicystic mesothelioma was made.
|Figure 1: Gross appearance of tumor measuring 250 × 180 × 80 mm and weigh 5800 gr showed multicystic with numerous thin walled translucent cysts|
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|Figure 3: Histopathological examination showed the cysts were separated by fibrous septa (H and E staining, ×40). Inset showed areas of acute and chronic inflammation and slight stromal cell proliferation (H and E staining, ×40)|
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At 18 months follow-up after surgery, the patient remained asymptomatic with no further growth.
| Discussion|| |
Multicystic peritoneal mesothelioma are borderline lesions, and they do not metastasize; however, they have a high propensity for local recurrence. The classic presenting signs and symptoms as seen in the present case are abdominal or pelvic mass, abdominal pain, and tenderness. ,
The tumor is clinically and radiologically undistinguishable from various benign and malignant mesenteric lesions, and the preoperative diagnosis of benign cystic mesotheliomas is difficult to make. Ultrasound and computerized tomography (CT) scan do not differentiate benign cystic mesotheliomas from other cystic lesions. Fine-needle aspiration in most cases is not informative. Magnetic resonance imaging (MRI) reveals a multiloculated cystic mass showing hypointensity on T1-weighted images and hyper or intermediate intensity on T2-weighed images and therefore may be very helpful for making a preoperative diagnosis. Laparoscopy is the most accurate diagnostic method since it allows local biopsy of the suspected lesions; however, it is an invasive procedure. Therefore, diagnostic procedures such as ultrasound, CT, and MRI can demonstrate an abnormality suggestive of this disorder while confirmation of the diagnosis is accomplished only at surgery.
Most of these tumors are usually large at the time of diagnosis (mean diameter, 13 cm).  In our case, the tumor was very large (25 × 18 × 13 cm) and weighed 5.8 kg. Very few such cases of huge tumors have been reported.  Exploratory laparotomy reveals characteristic numerous thin walled transparent cysts which are unevenly distributed in the serosal and subserosal tissue of the parietal and visceral peritoneum of the abdomen and pelvis, often forming multicystic masses. Histology shows round or irregularly shaped multiple cystic spaces of various sizes lined by flat and cuboidal mesothelial cells, and immunohistology shows calretinin and keratin staining. Transition between multicystic mesothelioma and adenomatoid tumor has been observed on several occasions. 
The most important histological differential diagnosis among benign lesions include cystic lymphangioma, cystic adenomatoid tumor, cystic forms of endosalpingiosis, endometriosis, müllerian cysts involving the retroperitoneum, and cystic mesonephric duct remnants while malignant lesions include malignant mesothelioma and serous tumors of the peritoneum. In addition to hematoxylin-eosin sections, immunohistochemical staining is useful in the differential diagnosis. , Among these, benign multicystic peritoneal mesothelioma is most likely to be confused with multilocular cystic lymphangioma; however, cystic lymphangioma is usually seen in males younger than 5 years. Microscopically, lymphoid aggregates and smooth muscle are present in their walls. Immunohistochemistry is also helpful in problematic cases. , The cystic component in cystic adenomatoid tumor is usually accompanied by a recognizable solid component. There are cases of tumors with mixed features of both. Thus, these two lesions are probably pathogenetically related.  Positive staining with calretinin, vimentin, and Wilms' tumor antigen and negative staining for Ber-EP-4, carcinoembryonic antigen (CEA), and CD15 indicate mesothelial lineage.  Malignant tumors mimicking benign multicystic mesothelioma show significant cytologic atypia or increased mitotic activity, at least focally within the lesion.  In addition, malignant mesothelioma grossly appears as multiple plaques or nodules, which are almost always associated with ascites. 
Aspiration cytology is of limited value in making a preoperative diagnosis.  In our patient, the aspiration cytology showed benign mesothelial cells against eosinophilic protenaceous background and occasional cells exhibiting presence of a brush border. Conditions such as cirrhosis, viral infections, and connective tissue disorders with mesothelial hyperplasia can also yield an aspirate with mesothelial cells, but in these conditions the cells tend to form clusters and aggregates as opposed to the large flat sheets seen in benign cystic mesothelioma. Rarely, the tumor may present as free floating pelvic cysts. 
The prognosis of multicystic peritoneal mesothelioma is excellent. The reported recurrence rate is slightly higher in women (40-50%) than in men (33%).  There are no specific uniform treatment strategies for peritoneal cystic mesothelioma. Complete eradication of all peritoneal cysts is the mainstay of therapy. In most cases, complete resection is not possible because the lateral margins of the lesion can often be seen to merge with the surrounding normal mesothelial covering. Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy using cisplatin or doxorubicin has been effective in several series of patients with peritoneal dissemination and demonstrating a prolonged disease-free survival.  Hormonal manipulation by use of tamoxifen and long-acting GnRH analogues as a therapeutic option for tumor reduction before anticipated surgery or management of recurrent lesions has been used in some cases.  Rosen and Sutton used potassium titanyl phosphate laser to treat these lesions. The laser penetrates to a depth of 2 mm, its primary effect being coagulation and vaporization. The authors consider this method to be efficacious in the treatment of multiple sites disease and, in addition, may reduce the need for repeated laparotomies. 
| Conclusion|| |
Multicystic peritoneal mesothelioma is an uncommon benign mesothelial proliferation that occurs mainly in women in the reproductive age. Histological examination with the aid of immunohistochemical techniques is essential for diagnosis. The prognosis is generally good. There are no efficient tools for early diagnosis and a long-term follow-up is needed due to the high incidence of recurrence.
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[Figure 1], [Figure 2], [Figure 3]