Peritoneal, benign, cystic mesothelioma with free-floating cysts, re-examined by new methods. A case report

Our plain-English summary of Peritoneal, benign, cystic mesothelioma with free-floating cysts, re-examined by new methods. A case report, by O.H. Iversen, T. Hovig, P. Brandtzaeg (APMIS, 1988).

The study

• Authors: O.H. Iversen, T. Hovig, P. Brandtzaeg
• Journal: APMIS
• Published: 1988;96(2):123-7
• Type of article: Case report
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A histologically-confirmed, multicystic, benign mesothelioma, with free-floating, thin-walled cysts, in the abdominal cavity of a 27-year-old woman was reported in 1954. After removal of all visible cysts by laparotomy, the patient was healthy and well for 29 years, when she was surgically treated for cholecystitis and gall bladder stones in 1982. The whole peritoneum was found covered with small cysts lined by mesothelial cells. The patient is (April 1987) well, with no complaints. Sections from the old paraffin blocks were studied by means of scanning, transmission electron microscopy and immunohistochemistry. These methods confirmed the histological diagnosis. The authors discuss whether such a lesion really is a benign tumor or should rather be otherwise classified.

In plain English

This case report described a woman who, at age 27 in 1953, had an operation for suspected appendicitis. Inside her abdomen the surgeon found thin-walled, fluid-filled cysts floating freely among the intestines. Some 30 cysts were removed, and the tissue was diagnosed as benign mesothelioma. She felt well for 29 years. In 1982, during an operation for gall bladder inflammation and gallstones, many small cysts up to 1 cm across were found covering the lining of the abdomen. They were lined with mesothelial cells. The authors reported she had been healthy since then. They re-examined the original 1953 tissue block with scanning and transmission electron microscopy and with a keratin stain. These methods showed features the authors called typical of mesothelioma, such as short microvilli and cell junctions, and confirmed the original diagnosis, although the old fixation had altered the cells' fine structure. The authors concluded that the long course confirmed the lesion was benign. They questioned whether it was truly a tumour or a developmental abnormality. The article does not mention asbestos or any other exposure.

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: case report; re-examination of archived tissue from one patient using electron microscopy and immunohistochemistry
• Who was studied: one woman, aged 27 in 1953, operated on in Norway in 1953 and again in 1982
• Main results:
  • At the 1953 operation, about 15 free-floating cysts emerged when the peritoneum was opened, and some 30 cysts in total were removed. The tissue was diagnosed as benign mesothelioma.
  • In 1982, during surgery for cholecystitis and gall bladder stones, the peritoneal surface all over the abdomen was covered with small cysts. The cysts sat on both the parietal and mesenterial peritoneum, were up to 1 cm in diameter, and were lined with mesothelial cells.
  • Scanning electron microscopy of the 1953 tissue showed numerous short microvilli on the cells lining the cysts.
  • Transmission electron microscopy of the 1953 tissue identified tight junctions, desmosomes and segments of a basal lamina.
  • Keratin staining (cytokeratin PKK1) of the 1953 tissue showed intense, diffuse staining in the cells lining the cysts.
  • The new methods confirmed the original histological diagnosis.
  • New sections of the 1982 cysts looked exactly like the 1953 cysts, except that they were attached (sessile) rather than free-floating.
  • The patient had been healthy since the 1982 operation.
• The authors' conclusion: The authors concluded that the course of the disease confirmed the lesion was benign. They questioned whether it is a true benign cystic mesothelioma or should be classified otherwise, for example as a cystic 'dysplasia' of the peritoneal lining.
• Limitations the authors state:
  • Because the tissue had originally been fixed in formaldehyde and embedded in paraffin, the fine structure of the cells was altered by fixation artifacts.
  • Vimentin, a protein found in mesothelial cells, is poorly preserved in formaldehyde-fixed tissue.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Peritoneal mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Laparotomy, Peritoneum, Mesothelial Cells, Paraffin Block, Transmission Electron Microscopy (TEM), Immunohistochemistry.

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