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Laparoscopic Diagnosis and Treatment of Pelvic Benign Multicystic Mesothelioma Associated with High CA19.9 Serum Concentration
Case Report
Laparoscopic Diagnosis and Treatment of Pelvic Benign Multicystic Mesothelioma Associated with High CA19.9 Serum Concentration Vincenzo Pinto, MD*, Angela Cristina Rossi, MD, Maria Grazia Fiore, MD, Vincenzo D’Addario, MD, and Ettore Cicinelli, MD From the Departments of Gynecology, Obstetrics, and Neonatology (Drs. Pinto, Rossi, D’ Addario, and Cicinelli) and Anatomical Pathology (Dr. Fiore), University Medical School of Bari, Bari, Italy.
ABSTRACT We report a case of benign multicystic mesothelioma in a 20-year-old woman referred because of amenorrhea. She underwent pelvic transabdominal ultrasound, which disclosed a micropolycystic appearance of the ovaries and a fluid collection in the pouch of Douglas. Tumor serum markers revealed an increase in CA19.9. Abdominal and pelvic computed tomography scans confirmed the presence of ascites. Laparoscopy disclosed small, thin-walled, translucent cysts in the Douglas cavity. The cysts were free-floating in a yellowish, sticky, gelatinous material. Microscopically, cystic lesions showed mesothelium-lined cystic spaces surrounded by a delicate thin fibrovascular wall. With immunohistochemistry, the tumor cells were strongly positive for cytokeratin and calretinin. These aspects were suggestive of benign multicystic mesothelioma. Electron microscopy confirmed the mesothelial nature of this tumor. Serial evaluation of the CA19.9 concentration showed a progressive decrease in the serum marker in the normal range. The patient is now well and symptom-free with no recurrence 24 months after surgery. The association between benign multicystic mesothelioma and increased CA19.9 serum concentration has been described only once, in a man. To our knowledge, this is the second case of benign multicystic mesothelioma associated with increased CA19.9 serum concentration and the first diagnosed in a woman. In the present case, a minimally invasive laparoscopic approach enabled not only histologic diagnosis of benign multicystic mesothelioma but also its surgical treatment. Although benign multicystic mesothelioma is a rare pathologic entity, it is important that sonologists include it in the differential diagnosis of diseases that manifest with ascites. Furthermore, all surgeons should be aware of the macroscopic and laparoscopic appearance of the lesion, and its generally benign course. Journal of Minimally Invasive Gynecology (2010) 17, 252–254 Ó 2010 AAGL. All rights reserved.
Benign multicystic mesotheliomas, also known as multilocular peritoneal inclusion cysts or mesothelial inclusion cysts, are benign lesions located primarily on the peritoneal surface covering the rectum, cul-de-sac, uterus, adnexa, and urinary bladder [1]. These lesions occur rarely, and their incidence and natural history remain unclear. They are sporadically described in case reports [2–5] and in small series [1,6]. It is generally believed that benign multicystic mesotheliomas are characterized by a slow progressive process with a high rate of relapse after surgical dissection [4], although transformation into malignant lesions is a rare and debated occurrence. The diagnosis is usually made during open or The authors have no commercial, proprietary, or financial interest in the products or companies described in this article. Corresponding author: Vincenzo Pinto, MD, Corso Umberto I, 14, 70042 Mola di Bari (BA), Italy. E-mail: [email protected] Submitted May 25, 2009. Accepted for publication November 11, 2009. Available at www.sciencedirect.com and www.jmig.org 1553-4650/$ - see front matter Ó 2010 AAGL. All rights reserved. doi:10.1016/j.jmig.2009.11.013
laparoscopic surgery concomitant with other well-defined diseases such as appendicitis, cholelithiasis, endometriosis, and ovarian neoplasms. We report an asymptomatic benign multicystic mesothelioma in a woman with increased CA19.9 serum levels and no concomitant disease. Case Report A 20-year-old woman was referred to our unit because of oligomenorrhea, which worsened in amenorrhea. She underwent pelvic transabdominal ultrasound, which revealed a normal uterus, a mild bilateral increase in ovarian volume, and a fluid collection in the pouch of Douglas. The ovaries also showed a micropolycystic appearance. Tumor serum markers (CA 125, CA 15.3, CA 19.9, carcinoembryonic antigen, ferritin, and b2-microglobulin) were assessed; only CA 19.9 was positive (401.6; range, 0–30.9). Hormonal assessment confirmed the diagnosis of polycystic ovary syndrome. Gastroscopy and colonoscopy did not reveal anomalies of the gastrointestinal system. Abdominal and pelvic
Pinto et al.
Benign Multicystic Mesothelioma and High CA19.9 Levels
computed tomography confirmed the presence of ascites; however, no useful information was added to the diagnosis. An exploratory laparoscopy was performed to investigate the presence of an abdominal mass that could have led to ascites and positive CA 19.9. Numerous thin-walled translucent cysts approximately 0.5 cm in greatest diameter were revealed in the serosal tissues of the parietal and visceral pelvic peritoneum. The cysts were free-floating in the Douglas cavity, in a yellowish, sticky, gelatinous material (Fig. 1). All of the cysts that gathered in the pelvis were removed, and multiple biopsies were performed on the peritoneum and both ovaries. Histopathologic analysis confirmed the mesothelial origin of the pelvic cysts. Microscopically, the cystic lesions showed typical morphologic features: multiple mesothelium-lined cystic spaces surrounded by a delicate thin fibrovascular wall containing occasional lymphocytes. The cells lining the spaces varied from flattened endothelium-like to cuboidal cells (Fig. 2A). Detached clumps of mesothelial cells within cystic spaces, hyperplastic-reactive modification of the mesothelium, adenomatoid changes, and squamous metaplasia were occasionally observed. There were no mitotic figures or muscle fibers within the cystic wall. With immunohistochemistry, the tumor cells were strongly positive for cytokeratin (AE1/AE3) and calretinin (Fig. 2B), and negative for factor VIII. These aspects were suggestive of a benign multicystic mesothelioma. Electron microscopy confirmed the mesothelial nature of the tumor. Biopsy specimens from the peritoneal surface were normal, whereas those from the ovaries confirmed the micropolycystic aspects. The patient was counselled and referred for follow-up. Serial evaluation of the CA 19.9 concentration showed a progressive decrease in the serum marker in the normal range. The patient is now well and symptom-free with no recurrence 24 months after surgery. Follow-up consists of evaluation of CA 19.9 serum concentrations, and abdominal and pelvic sonography every 6 months.
253
Fig. 1. Numerous free-floating cysts in the pouch of Douglas, in a gelatinous sticky material. The ovaries show a micropolycystic appearance.
ease. In contrast, because of lack of previous surgery, low incidence of previous abdominal infections, and documentation of disease-related death, other authors [6,8] support a neoplastic rather than a reactive basis for these lesions. In the series of 25 cases reported by Weiss and Tavassoli [6],
Discussion Benign multicystic mesothelioma is a rare lesion of unknown pathogenesis with uncertain malignant potential and no uniform treatment strategy [1,6]. It occurs more frequently in young to middle-aged women, but may also be frequently seen after menopause [3]. Only a few cases of benign multicystic mesothelioma have been described in male patients [5,7]. The etiology of benign multicystic mesothelioma is still unclear, and there is controversy about its reactive or neoplastic nature. Some authors [4,7] have suggested that benign multicystic mesothelioma cysts are multiple inclusion cysts that result from a proliferative reaction within the peritoneal tissue. They are considered a peculiar peritoneal reaction to chronic irritation stimuli, with mesothelial cell entrapment, reactive proliferation, and cystic formation [4,7]. According to this hypothesis, the lesions are often associated with a history of pelvic inflammatory dis-
Fig. 2. A, Mesothelial lining of cysts varies from flattened endotheliallike to cuboidal cells (hematoxylin-eosin; original magnification !200). B, Peroxidase-antiperoxidase immunostain for calretinin shows reactivity of cells lining cystic spaces (original magnification !100).
254
2 patients died of benign multicystic mesothelioma, and in 1 patient, benign multicystic mesothelioma showed transition to conventional malignant mesothelioma. A clear malignant transformation to an invasive process has been described also in other studies [8]. In most cases, benign multicystic mesothelioma is asymptomatic and diagnosed incidentally [4]. In the present case, amenorrhea, because of which the patient was referred to our unit, was due to polycystic ovary syndrome. The evidence of ascites and the increase in CA 19.9 concentration were the only anomalies that we were able to detect before an explorative laparoscopy was performed. Although our case report is limited by a short follow-up, it highlights 2 important topics on the occurrence of benign multicystic mesothelioma. First, the condition may be totally asymptomatic. Second, the presence of a mild fluid collection in the Douglas cavity could be the only sign of benign multicystic mesothelioma. In this case, lack of visualization of the cysts at transabdominal sonography and computed tomography could be due to the extremely thin fibrovascular wall and to the gelatinous fluid in which they were embedded, giving the appearance of ascites. Detection of fluid within the pelvis in the absence of major signs such as suspected ovarian masses, together with an increase in CA 19.9 concentration, should arouse suspicion of a benign multicystic mesothelioma after exclusion of pathologic conditions more frequently associated with ascites. CA 19.9 is an antigen, detected by a monoclonal antibody, that recognizes carbohydrate chain sialyl Lewis A. It is expressed on some tumor cells and has a role in adhesion between tumor and endothelial cells. Sialyl Lewis A is secreted into the serum, and is used as a marker for detection and follow-up of abdominal epithelial tumors, especially pancreatic adenocarcinomas but also hepatobiliary and colorectal carcinomas. To our knowledge, this is the second case of benign multicystic mesothelioma associated with increased CA 19.9 serum concentration, and the first diagnosed in a woman. In the first report, by Holtzman et al [9], and in a case of benign mesothelial splenic cyst with high CA 19.9 serum concentrations [10], it was suggested that metaplastic changes in mesothelial cells were responsible for secretion of this marker. Adenomatoid change or squamous metaplasia of the mesothelium occurs in one-third of benign multicystic mesotheliomas [6]. Both of these features are described in our case, together with hyperplastic reactive modification of the mesothelium. It is unlikely that these aspects could be related to the increased CA 19.9 serum concentration. CA 19.9 is considered the best serum tumor marker for pancreatobiliary cancer; however, its sensitivity, specificity, and predictive values limit its use as a reliable test. Increased CA 19.9 has a positive predictive value for pancreatobiliary malignancy of only 69%. It is well known that moderately increased concentrations of CA 19.9 can be found in 15% to 36% of patients, and there is no explanation for the increased CA 19.9 serum concentration in 8.8% of above-normal values [11]. This antigen is related to the Lewis blood group; thus,
Journal of Minimally Invasive Gynecology, Vol 17, No 2, March/April 2010
individuals with Lewis-null blood type cannot produce CA 19.9, and approximately 5% of persons will not test positive for CA 19.9. Thus, the clinical usefulness of this marker for monitoring cancer is considered far better than that for diagnosis of cancer. Further investigation is necessary to elucidate the significance of CA 19.9 in benign multicystic mesotheliomas; however, we should not exclude a higher degenerative potential of cystic epithelium that produces dedifferentiated proteins. At this time, we suggest periodic measurements of this tumor marker to check for recurrence. It may be difficult to differentiate benign multicystic mesothelioma from other cystic neoplastic or inflammatory lesions of the peritoneum such as multilocular cystic lymphangioma, cystic adenomatoid tumors, mu¨llerian cysts involving the peritoneum, and epithelial inclusion cysts [4,12]. In some cases, the diagnosis is confirmed only at electron microscopy and immunohistochemistry (positivity for cytokeratin and calretinin). In conclusion, although benign multicystic mesothelioma is a rare pathologic entity, it is important that sonologists include it in the differential diagnosis of diseases that manifest with ascites. Furthermore, all surgeons should be aware of the macroscopic and laparoscopic appearance of the lesions and of its generally benign course. Lack of long-term longitudinal studies, risk of local recurrence, and malignant transformation suggest careful follow-up.
References 1. Urbanczyk K, Skotniczny K, Kucinski J, et al. Mesothelial inclusion cysts (so-called benign cystic mesothelioma): a clinicopathological analysis of six cases. Pol J Pathol. 2005;56:81–87. 2. Adolph AJ, Smith TE, Adolph J. Benign multicystic mesothelioma: a case report. J Obstet Gynaecol Can. 2002;24:246–247. 3. Saad S, Brockmann M, Maegele M. Benign peritoneal multicystic mesothelioma diagnosed and treated by laparoscopic surgery. J Laparoendosc Adv Surg Tech A. 2007;17:649–652. 4. Safioleas MC, Kontzoglou C, Stamatakos M, et al. Benign multicystic mesothelioma: a case report and review of the literature. World J Gastroenterol. 2006;12:5739–5742. 5. Takenouchi Y, Oda K, Takahara O, et al. Report of a case of benign cystic mesothelioma. Am J Gastroenterol. 1995;90:1165–1167. 6. Weiss SW, Tavassoli FA. Multicystic mesothelioma: an analysis of pathologic findings and biologic behavior in 37 cases. Am J Surg Pathol. 1988;12:737–746. 7. Vara-Thorbeck C, Toscano-Mendez R. Peritoneal cystic mesothelioma. Surg Endosc. 2002;16:220. 8. Gonzalez-Moreno S, Yan H, Alcorn KV, et al. Malignant transformation of ‘‘benign’’ cystic mesothelioma of the peritoneum. J Surg Oncol. 2002;79:243–251. 9. Holtzman RN, Heymann D, Bordone F, et al. Carbohydrate antigen 19.9 and carcinoembryonic antigen immunostaining in benign multicystic mesothelioma of the peritoneum. Arch Pathol Lab Med. 2001;125:944–947. 10. Walz MK, Metz KA, Sastry M, et al. Benign mesothelial splenic cyst may cause high serum concentration of CA 19.9. Eur J Surg. 1994; 160:389–391. 11. Osswald BR, Klee FE, Wysocki S. The reliability of highly elevated CA 19.9 levels. Dis Markers. 1993;11:275–278. 12. Abdullahi H, Fawzi H. Gynaecological presentation of benign multicystic mesothelioma. J Obstet Gynaecol. 2003;23:576.
Laparoscopic Diagnosis and Treatment of Pelvic Benign Multicystic Mesothelioma Associated with High CA19.9 Serum Concentration Vincenzo Pinto, MD*, Angela Cristina Rossi, MD, Maria Grazia Fiore, MD, Vincenzo D’Addario, MD, and Ettore Cicinelli, MD From the Departments of Gynecology, Obstetrics, and Neonatology (Drs. Pinto, Rossi, D’ Addario, and Cicinelli) and Anatomical Pathology (Dr. Fiore), University Medical School of Bari, Bari, Italy.
ABSTRACT We report a case of benign multicystic mesothelioma in a 20-year-old woman referred because of amenorrhea. She underwent pelvic transabdominal ultrasound, which disclosed a micropolycystic appearance of the ovaries and a fluid collection in the pouch of Douglas. Tumor serum markers revealed an increase in CA19.9. Abdominal and pelvic computed tomography scans confirmed the presence of ascites. Laparoscopy disclosed small, thin-walled, translucent cysts in the Douglas cavity. The cysts were free-floating in a yellowish, sticky, gelatinous material. Microscopically, cystic lesions showed mesothelium-lined cystic spaces surrounded by a delicate thin fibrovascular wall. With immunohistochemistry, the tumor cells were strongly positive for cytokeratin and calretinin. These aspects were suggestive of benign multicystic mesothelioma. Electron microscopy confirmed the mesothelial nature of this tumor. Serial evaluation of the CA19.9 concentration showed a progressive decrease in the serum marker in the normal range. The patient is now well and symptom-free with no recurrence 24 months after surgery. The association between benign multicystic mesothelioma and increased CA19.9 serum concentration has been described only once, in a man. To our knowledge, this is the second case of benign multicystic mesothelioma associated with increased CA19.9 serum concentration and the first diagnosed in a woman. In the present case, a minimally invasive laparoscopic approach enabled not only histologic diagnosis of benign multicystic mesothelioma but also its surgical treatment. Although benign multicystic mesothelioma is a rare pathologic entity, it is important that sonologists include it in the differential diagnosis of diseases that manifest with ascites. Furthermore, all surgeons should be aware of the macroscopic and laparoscopic appearance of the lesion, and its generally benign course. Journal of Minimally Invasive Gynecology (2010) 17, 252–254 Ó 2010 AAGL. All rights reserved.
Benign multicystic mesotheliomas, also known as multilocular peritoneal inclusion cysts or mesothelial inclusion cysts, are benign lesions located primarily on the peritoneal surface covering the rectum, cul-de-sac, uterus, adnexa, and urinary bladder [1]. These lesions occur rarely, and their incidence and natural history remain unclear. They are sporadically described in case reports [2–5] and in small series [1,6]. It is generally believed that benign multicystic mesotheliomas are characterized by a slow progressive process with a high rate of relapse after surgical dissection [4], although transformation into malignant lesions is a rare and debated occurrence. The diagnosis is usually made during open or The authors have no commercial, proprietary, or financial interest in the products or companies described in this article. Corresponding author: Vincenzo Pinto, MD, Corso Umberto I, 14, 70042 Mola di Bari (BA), Italy. E-mail: [email protected] Submitted May 25, 2009. Accepted for publication November 11, 2009. Available at www.sciencedirect.com and www.jmig.org 1553-4650/$ - see front matter Ó 2010 AAGL. All rights reserved. doi:10.1016/j.jmig.2009.11.013
laparoscopic surgery concomitant with other well-defined diseases such as appendicitis, cholelithiasis, endometriosis, and ovarian neoplasms. We report an asymptomatic benign multicystic mesothelioma in a woman with increased CA19.9 serum levels and no concomitant disease. Case Report A 20-year-old woman was referred to our unit because of oligomenorrhea, which worsened in amenorrhea. She underwent pelvic transabdominal ultrasound, which revealed a normal uterus, a mild bilateral increase in ovarian volume, and a fluid collection in the pouch of Douglas. The ovaries also showed a micropolycystic appearance. Tumor serum markers (CA 125, CA 15.3, CA 19.9, carcinoembryonic antigen, ferritin, and b2-microglobulin) were assessed; only CA 19.9 was positive (401.6; range, 0–30.9). Hormonal assessment confirmed the diagnosis of polycystic ovary syndrome. Gastroscopy and colonoscopy did not reveal anomalies of the gastrointestinal system. Abdominal and pelvic
Pinto et al.
Benign Multicystic Mesothelioma and High CA19.9 Levels
computed tomography confirmed the presence of ascites; however, no useful information was added to the diagnosis. An exploratory laparoscopy was performed to investigate the presence of an abdominal mass that could have led to ascites and positive CA 19.9. Numerous thin-walled translucent cysts approximately 0.5 cm in greatest diameter were revealed in the serosal tissues of the parietal and visceral pelvic peritoneum. The cysts were free-floating in the Douglas cavity, in a yellowish, sticky, gelatinous material (Fig. 1). All of the cysts that gathered in the pelvis were removed, and multiple biopsies were performed on the peritoneum and both ovaries. Histopathologic analysis confirmed the mesothelial origin of the pelvic cysts. Microscopically, the cystic lesions showed typical morphologic features: multiple mesothelium-lined cystic spaces surrounded by a delicate thin fibrovascular wall containing occasional lymphocytes. The cells lining the spaces varied from flattened endothelium-like to cuboidal cells (Fig. 2A). Detached clumps of mesothelial cells within cystic spaces, hyperplastic-reactive modification of the mesothelium, adenomatoid changes, and squamous metaplasia were occasionally observed. There were no mitotic figures or muscle fibers within the cystic wall. With immunohistochemistry, the tumor cells were strongly positive for cytokeratin (AE1/AE3) and calretinin (Fig. 2B), and negative for factor VIII. These aspects were suggestive of a benign multicystic mesothelioma. Electron microscopy confirmed the mesothelial nature of the tumor. Biopsy specimens from the peritoneal surface were normal, whereas those from the ovaries confirmed the micropolycystic aspects. The patient was counselled and referred for follow-up. Serial evaluation of the CA 19.9 concentration showed a progressive decrease in the serum marker in the normal range. The patient is now well and symptom-free with no recurrence 24 months after surgery. Follow-up consists of evaluation of CA 19.9 serum concentrations, and abdominal and pelvic sonography every 6 months.
253
Fig. 1. Numerous free-floating cysts in the pouch of Douglas, in a gelatinous sticky material. The ovaries show a micropolycystic appearance.
ease. In contrast, because of lack of previous surgery, low incidence of previous abdominal infections, and documentation of disease-related death, other authors [6,8] support a neoplastic rather than a reactive basis for these lesions. In the series of 25 cases reported by Weiss and Tavassoli [6],
Discussion Benign multicystic mesothelioma is a rare lesion of unknown pathogenesis with uncertain malignant potential and no uniform treatment strategy [1,6]. It occurs more frequently in young to middle-aged women, but may also be frequently seen after menopause [3]. Only a few cases of benign multicystic mesothelioma have been described in male patients [5,7]. The etiology of benign multicystic mesothelioma is still unclear, and there is controversy about its reactive or neoplastic nature. Some authors [4,7] have suggested that benign multicystic mesothelioma cysts are multiple inclusion cysts that result from a proliferative reaction within the peritoneal tissue. They are considered a peculiar peritoneal reaction to chronic irritation stimuli, with mesothelial cell entrapment, reactive proliferation, and cystic formation [4,7]. According to this hypothesis, the lesions are often associated with a history of pelvic inflammatory dis-
Fig. 2. A, Mesothelial lining of cysts varies from flattened endotheliallike to cuboidal cells (hematoxylin-eosin; original magnification !200). B, Peroxidase-antiperoxidase immunostain for calretinin shows reactivity of cells lining cystic spaces (original magnification !100).
254
2 patients died of benign multicystic mesothelioma, and in 1 patient, benign multicystic mesothelioma showed transition to conventional malignant mesothelioma. A clear malignant transformation to an invasive process has been described also in other studies [8]. In most cases, benign multicystic mesothelioma is asymptomatic and diagnosed incidentally [4]. In the present case, amenorrhea, because of which the patient was referred to our unit, was due to polycystic ovary syndrome. The evidence of ascites and the increase in CA 19.9 concentration were the only anomalies that we were able to detect before an explorative laparoscopy was performed. Although our case report is limited by a short follow-up, it highlights 2 important topics on the occurrence of benign multicystic mesothelioma. First, the condition may be totally asymptomatic. Second, the presence of a mild fluid collection in the Douglas cavity could be the only sign of benign multicystic mesothelioma. In this case, lack of visualization of the cysts at transabdominal sonography and computed tomography could be due to the extremely thin fibrovascular wall and to the gelatinous fluid in which they were embedded, giving the appearance of ascites. Detection of fluid within the pelvis in the absence of major signs such as suspected ovarian masses, together with an increase in CA 19.9 concentration, should arouse suspicion of a benign multicystic mesothelioma after exclusion of pathologic conditions more frequently associated with ascites. CA 19.9 is an antigen, detected by a monoclonal antibody, that recognizes carbohydrate chain sialyl Lewis A. It is expressed on some tumor cells and has a role in adhesion between tumor and endothelial cells. Sialyl Lewis A is secreted into the serum, and is used as a marker for detection and follow-up of abdominal epithelial tumors, especially pancreatic adenocarcinomas but also hepatobiliary and colorectal carcinomas. To our knowledge, this is the second case of benign multicystic mesothelioma associated with increased CA 19.9 serum concentration, and the first diagnosed in a woman. In the first report, by Holtzman et al [9], and in a case of benign mesothelial splenic cyst with high CA 19.9 serum concentrations [10], it was suggested that metaplastic changes in mesothelial cells were responsible for secretion of this marker. Adenomatoid change or squamous metaplasia of the mesothelium occurs in one-third of benign multicystic mesotheliomas [6]. Both of these features are described in our case, together with hyperplastic reactive modification of the mesothelium. It is unlikely that these aspects could be related to the increased CA 19.9 serum concentration. CA 19.9 is considered the best serum tumor marker for pancreatobiliary cancer; however, its sensitivity, specificity, and predictive values limit its use as a reliable test. Increased CA 19.9 has a positive predictive value for pancreatobiliary malignancy of only 69%. It is well known that moderately increased concentrations of CA 19.9 can be found in 15% to 36% of patients, and there is no explanation for the increased CA 19.9 serum concentration in 8.8% of above-normal values [11]. This antigen is related to the Lewis blood group; thus,
Journal of Minimally Invasive Gynecology, Vol 17, No 2, March/April 2010
individuals with Lewis-null blood type cannot produce CA 19.9, and approximately 5% of persons will not test positive for CA 19.9. Thus, the clinical usefulness of this marker for monitoring cancer is considered far better than that for diagnosis of cancer. Further investigation is necessary to elucidate the significance of CA 19.9 in benign multicystic mesotheliomas; however, we should not exclude a higher degenerative potential of cystic epithelium that produces dedifferentiated proteins. At this time, we suggest periodic measurements of this tumor marker to check for recurrence. It may be difficult to differentiate benign multicystic mesothelioma from other cystic neoplastic or inflammatory lesions of the peritoneum such as multilocular cystic lymphangioma, cystic adenomatoid tumors, mu¨llerian cysts involving the peritoneum, and epithelial inclusion cysts [4,12]. In some cases, the diagnosis is confirmed only at electron microscopy and immunohistochemistry (positivity for cytokeratin and calretinin). In conclusion, although benign multicystic mesothelioma is a rare pathologic entity, it is important that sonologists include it in the differential diagnosis of diseases that manifest with ascites. Furthermore, all surgeons should be aware of the macroscopic and laparoscopic appearance of the lesions and of its generally benign course. Lack of long-term longitudinal studies, risk of local recurrence, and malignant transformation suggest careful follow-up.
References 1. Urbanczyk K, Skotniczny K, Kucinski J, et al. Mesothelial inclusion cysts (so-called benign cystic mesothelioma): a clinicopathological analysis of six cases. Pol J Pathol. 2005;56:81–87. 2. Adolph AJ, Smith TE, Adolph J. Benign multicystic mesothelioma: a case report. J Obstet Gynaecol Can. 2002;24:246–247. 3. Saad S, Brockmann M, Maegele M. Benign peritoneal multicystic mesothelioma diagnosed and treated by laparoscopic surgery. J Laparoendosc Adv Surg Tech A. 2007;17:649–652. 4. Safioleas MC, Kontzoglou C, Stamatakos M, et al. Benign multicystic mesothelioma: a case report and review of the literature. World J Gastroenterol. 2006;12:5739–5742. 5. Takenouchi Y, Oda K, Takahara O, et al. Report of a case of benign cystic mesothelioma. Am J Gastroenterol. 1995;90:1165–1167. 6. Weiss SW, Tavassoli FA. Multicystic mesothelioma: an analysis of pathologic findings and biologic behavior in 37 cases. Am J Surg Pathol. 1988;12:737–746. 7. Vara-Thorbeck C, Toscano-Mendez R. Peritoneal cystic mesothelioma. Surg Endosc. 2002;16:220. 8. Gonzalez-Moreno S, Yan H, Alcorn KV, et al. Malignant transformation of ‘‘benign’’ cystic mesothelioma of the peritoneum. J Surg Oncol. 2002;79:243–251. 9. Holtzman RN, Heymann D, Bordone F, et al. Carbohydrate antigen 19.9 and carcinoembryonic antigen immunostaining in benign multicystic mesothelioma of the peritoneum. Arch Pathol Lab Med. 2001;125:944–947. 10. Walz MK, Metz KA, Sastry M, et al. Benign mesothelial splenic cyst may cause high serum concentration of CA 19.9. Eur J Surg. 1994; 160:389–391. 11. Osswald BR, Klee FE, Wysocki S. The reliability of highly elevated CA 19.9 levels. Dis Markers. 1993;11:275–278. 12. Abdullahi H, Fawzi H. Gynaecological presentation of benign multicystic mesothelioma. J Obstet Gynaecol. 2003;23:576.