Peritoneal mesothelial hyperplasia associated with gynaecological disease: a potential diagnostic pitfall that is commonly associated with endometriosis

Our plain-English summary of Peritoneal mesothelial hyperplasia associated with gynaecological disease: a potential diagnostic pitfall that is commonly associated with endometriosis, by R. Oparka, W.G. McCluggage, C.S. Herrington (Journal of Clinical Pathology, 2011).

The study

• Authors: R. Oparka, W.G. McCluggage, C.S. Herrington
• Journal: Journal of Clinical Pathology
• Published: 2011;64(4):313-8
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims: To describe the clinicopathological features of florid peritoneal mesothelial hyperplasia associated with gynaecological disease.

Methods: Review of a series of 44 cases where there was significant peritoneal mesothelial proliferation, usually on the surface of the ovary, which resulted in diagnostic problems, often including a consideration of malignancy.

Results: Florid mesothelial proliferation was associated with a variety of benign and malignant lesions, most commonly endometriosis. The most characteristic morphological appearance was that of small bland tubules and nests and cords of cells often embedded in fibrous tissue, sometimes with a linear arrangement. In a minority of cases, there were closely packed small glands and papillae resulting in mimicry of a serous proliferation; psammoma bodies were present in one such case. In several cases, the groups of mesothelial cells either exhibited true lymphovascular invasion or were surrounded by spaces closely simulating lymphovascular invasion. Although most cases were appreciated to represent a reactive mesothelial proliferation, several were referred with a presumed or possible diagnosis of mesothelioma, low-grade serous carcinoma, adenocarcinoma, adenomatoid tumour or Sertoli cell tumour. Positive staining with calretinin and negative staining with Ber-EP4 often helped to identify the cells as mesothelial rather than epithelial.

Conclusions: Florid peritoneal mesothelial hyperplasia can occur in association with a variety of gynaecological disorders. Recognition of this phenomenon and appreciation that it can produce worrisome histological patterns, particularly when associated with endometriosis, is key to reaching the correct diagnosis.

In plain English

This study, from pathology departments in Belfast and Dundee, UK, reviewed 44 cases in which an unusually extensive growth of the cells lining the abdominal cavity (peritoneal mesothelial hyperplasia), usually on the surface of the ovary, caused diagnostic difficulty, often including a question of cancer. The article does not study asbestos or any other exposure. The growth occurred alongside non-cancerous conditions in 38 cases, most often ovarian endometriosis (29 cases), and alongside tumours in six cases. All patients with endometriosis were under 50 (aged 22 to 49). Under the microscope, the cells usually formed small tubules, solid nests and cords set in fibrous tissue, with at most mild nuclear atypia and no necrosis. In some cases, groups of cells lay inside true vascular spaces, a feature that can suggest cancer. Several cases had been referred with a presumed or possible diagnosis of mesothelioma or other tumours. Staining for calretinin and Ber-EP4 aided diagnosis in 14 of the 19 cases where staining was done. The authors concluded that recognising this reactive growth, particularly with endometriosis, is key to reaching the correct diagnosis.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective case series (review of pathology slides from hospital archives and consultation files)
• Who was studied: 44 cases of florid peritoneal mesothelial proliferation in women with gynaecological disease, from the pathology archives of Royal Victoria Hospital, Belfast and Ninewells Hospital, Dundee (UK), and the authors' consultation files. The article gives no dates for when the cases occurred.
• Exposure: No exposure was studied. The article concerns associated gynaecological conditions (mainly endometriosis) and does not mention asbestos or any fiber.
• Main results:
  • Of the 44 cases, the mesothelial proliferation was associated with non-neoplastic lesions in 38 and with neoplastic lesions in 6.
  • The most common associated non-neoplastic lesion was ovarian endometriosis (29 cases). The others were tubo-ovarian abscesses (3), paraovarian cysts (2), follicular cysts (2), a torted ovary (1), and one case with no associated lesion.
  • All patients with endometriosis were under 50 (range 22 to 49, median 37). Patients with other non-neoplastic lesions were aged 32 to 62 (median 41). Patients with neoplastic lesions were aged 24 to 68 (median 38).
  • The proliferating mesothelial cells were on the ovarian surface in 41 of the 44 cases.
  • The cells showed at most mild nuclear atypia and only very occasional mitoses, and there was no necrosis.
  • Groups of mesothelial cells occasionally appeared within true vascular spaces, which was confirmed by CD34 immunohistochemistry.
  • A minority of cases showed closely packed small glands and papillae that mimicked a serous proliferation. Psammoma bodies were present in one of these cases. All of these cases were associated with endometriosis.
  • Several cases had been referred with a presumed or possible diagnosis of mesothelioma, low-grade serous carcinoma, adenocarcinoma, adenomatoid tumour or Sertoli cell tumour.
  • Immunohistochemistry was performed in 19 cases. Calretinin and Ber-EP4 staining aided diagnosis in 14 of them: the mesothelial cells were calretinin positive and Ber-EP4 negative.
• The authors' conclusion: The authors concluded that florid peritoneal mesothelial hyperplasia can occur with a variety of gynaecological disorders. They concluded that recognising it, and knowing that it can produce worrisome patterns under the microscope (particularly with endometriosis), is key to reaching the correct diagnosis.

Topics

Medical terms in this study, explained in our Lexicon: Reactive Mesothelial Hyperplasia, Tubule, Papillae, Mesothelial Cells, Mesothelioma, Carcinoma, Adenocarcinoma, Adenomatoid Tumor.

Related studies

• Peritoneal malignant mesothelioma (PMM), and primary peritoneal serous carcinoma (PPSC) and reactive mesothelial hyperplasia (RMH) of the peritoneum. Immunohistochemical and fluorescence in situ hybridisation (FISH) analyses — T. Kawai, S. Tominaga, et al. (2016)
• Malignant peritoneal mesothelioma in patients with endometriosis — K.J. Butnor, J. Rueckert, et al. (2018)
• Value of mesothelial and epithelial antibodies in distinguishing diffuse peritoneal mesothelioma in females from serous papillary carcinoma of the ovary and peritoneum — R.L. Attanoos, R. Webb, et al. (2002)
• Selected topics in peritoneal pathology — P.M. Baker, P.B. Clement, et al. (2014)
• p16/CDKN2A FISH in Differentiation of Diffuse Malignant Peritoneal Mesothelioma From Mesothelial Hyperplasia and Epithelial Ovarian Cancer — T. Ito, M. Hamasaki, et al. (2015)
• Laparoscopic management of peritoneal mesothelioma associated with pelvic endometriosis — F.R. Nezhat, S.M. DeNoble, et al. (2010)

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