title: Peritoneal mesothelial hyperplasia associated with gynaecological disease: a potential diagnostic pitfall that is commonly associated with endometriosis.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Pathology, Ninewells Hospital and Medical School, Dundee, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Oparka
authors.forename: W Glenn
authors.initials: WG
authors.lastname: McCluggage
authors.forename: C Simon
authors.initials: CS
authors.lastname: Herrington
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D064032:Calbindin 2; D049109:Cell Proliferation; D003937:Diagnosis, Differential; D004715:Endometriosis / Q000150:complications*; D004848:Epithelium / Q000473:pathology; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000175:diagnosis / Q000209:etiology / Q000473:pathology; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000175:diagnosis; D010053:Ovary / Q000473:pathology; D010534:Peritoneal Neoplasms / Q000175:diagnosis; D010537:Peritoneum / Q000473:pathology*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D055815:Young Adult; D000951:Antigens, Neoplasm
chemical_list: D015415:Biomarkers; D014408:Biomarkers, Tumor; D064032:Calbindin 2; D064030:S100 Calcium Binding Protein G; C576764:CALB2 protein, human; C115012:human epithelial antigen-125; D000951:Antigens, Neoplasm