6 May 2011 - Case #205
All cases are archived on our website. To view them sorted by case number, diagnosis or category, visit our main Case of the Month page. To subscribe or unsubscribe to Case of the Month or our other email lists, click here.
Thanks to Eddie Fridman, The Chaim Sheba Medical Center (Israel), for contributing this case. This case was reviewed in May 2020 by Dr. Jennifer Bennett, University of Chicago and Dr. Carlos Parra-Herran, University of Toronto.
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Case #205
Clinical history:
A previously healthy 36 year old woman was operated on due to multiple small cystic lesions of the pelvic peritoneum and small bowel mesentery. Both ovaries were unremarkable. Sections are of the cystic areas.
Microscopic images:
What is your diagnosis?
Diagnosis: Benign cystic mesothelioma
Discussion:
Benign cystic mesothelioma, also called multicystic mesothelioma, is a rare tumor that occurs most frequently in women of reproductive age and is difficult to diagnose preoperatively (J Med Case Reports 2010;4:385). It is often associated with prior pelvic surgery, endometriosis or pelvic inflammatory disease but is not associated with asbestos (J Obstet Gynaecol Res 2011;37:1126). Some cases may be neoplastic and others may be caused by inflammation and adhesions (Int J Gynecol Pathol 2011;30:163).
Grossly, the tumors are usually large and may be multifocal or unilocular. Free floating cysts may also occur. Morphologically, the mesothelial cells lining the cysts vary from flattened to endothelial-like to cuboidal. The cysts are thin walled and may contain eosinophilic fluid. Inflammatory cells are often present within the stroma between the cysts. Foci of mesothelial hyperplasia may also be present, as in this case. The lining cells are immunoreactive for keratin and calretinin (Hum Pathol 2003;34:369).
The differential diagnosis includes:
Complete surgical resection of benign cystic mesothelioma is recommended. Follow up is necessary because 50% of tumors recur after excision.
All cases are archived on our website. To view them sorted by case number, diagnosis or category, visit our main Case of the Month page. To subscribe or unsubscribe to Case of the Month or our other email lists, click here.
Thanks to Eddie Fridman, The Chaim Sheba Medical Center (Israel), for contributing this case. This case was reviewed in May 2020 by Dr. Jennifer Bennett, University of Chicago and Dr. Carlos Parra-Herran, University of Toronto.
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Website news:
(1) We are currently updating these chapters: Bladder, Cervix-Cytology and Stains.
(2) We are always looking for reviewers of our chapters, or parts of chapters. If interested, email us your CV and the chapters / topics you are interested in reviewing. More information about reviewing is found here.
Visit and follow our Blog to see recent updates to the website.
(1) We are currently updating these chapters: Bladder, Cervix-Cytology and Stains.
(2) We are always looking for reviewers of our chapters, or parts of chapters. If interested, email us your CV and the chapters / topics you are interested in reviewing. More information about reviewing is found here.
Visit and follow our Blog to see recent updates to the website.
Case #205
Clinical history:
A previously healthy 36 year old woman was operated on due to multiple small cystic lesions of the pelvic peritoneum and small bowel mesentery. Both ovaries were unremarkable. Sections are of the cystic areas.
Microscopic images:
Left: CD31, right: MNF-116
What is your diagnosis?
Click here for diagnosis and discussion:
Diagnosis: Benign cystic mesothelioma
Discussion:
Benign cystic mesothelioma, also called multicystic mesothelioma, is a rare tumor that occurs most frequently in women of reproductive age and is difficult to diagnose preoperatively (J Med Case Reports 2010;4:385). It is often associated with prior pelvic surgery, endometriosis or pelvic inflammatory disease but is not associated with asbestos (J Obstet Gynaecol Res 2011;37:1126). Some cases may be neoplastic and others may be caused by inflammation and adhesions (Int J Gynecol Pathol 2011;30:163).
Grossly, the tumors are usually large and may be multifocal or unilocular. Free floating cysts may also occur. Morphologically, the mesothelial cells lining the cysts vary from flattened to endothelial-like to cuboidal. The cysts are thin walled and may contain eosinophilic fluid. Inflammatory cells are often present within the stroma between the cysts. Foci of mesothelial hyperplasia may also be present, as in this case. The lining cells are immunoreactive for keratin and calretinin (Hum Pathol 2003;34:369).
The differential diagnosis includes:
- Lymphangioma: younger patients, may contain chylous fluid grossly, often lymphoid aggregates and smooth muscle within walls, D2-40+
- Other mesenteric / omental cysts / pseudocysts: usually unilocular, no distinct cyst wall or internal septa, keratin and calretinin negative
- Cystic teratoma: usually contains adipose and calcifications
- Loculated ascitis: usually has irregular borders, is surrounded by bowel loops or abdominal / pelvic organs
Complete surgical resection of benign cystic mesothelioma is recommended. Follow up is necessary because 50% of tumors recur after excision.
