Well-differentiated papillary mesothelioma of the peritoneum: a separate entity

Our plain-English summary of Well-differentiated papillary mesothelioma of the peritoneum: a separate entity, by K. Hoekman, G. Tognon, E.K. Risse, et al (European Journal of Cancer, 1996).

The study

• Authors: K. Hoekman, G. Tognon, E.K. Risse, C.A. Bloemsma, J.B. Vermorken
• Journal: European Journal of Cancer
• Published: 1996;32A(2):255-8
• Type of article: Case report
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Three female patients with a diffuse well-differentiated papillary mesothelioma of the peritoneum are presented. They did not have a history of exposure to asbestos. The peritoneal biopsies were studied extensively, including electron microscopy, nuclear morphometry and DNA ploidy analysis. The results from these more sophisticated investigations confirmed the mesothelial origin and further characterised these lesions. One of the 3 patients has continuing elevated serum CA-125 levels, which increased transiently during and after pregnancy. All 3 patients have done well without therapy, 2 patients being alive and non-symptomatic 6 and 7 years after the initial diagnosis. It is important to distinguish this disorder from the malignant diseases of the peritoneum and the ovary. In view of the indolent course of this subtype of mesothelioma, avoidance of treatment is justified unless there is evidence of progressive disease.

In plain English

This article reported three cases of diffuse well-differentiated papillary mesothelioma (WDPM) of the peritoneum (the abdominal lining) in the Netherlands. All three were women, aged 30, 36 and 44 at diagnosis. The authors reported that none had a history of exposure to asbestos. In each case the disease was found by chance during surgery for another reason. Electron microscopy showed many microvilli and desmosomes in all three, which the authors took as confirming mesothelial origin. One patient's blood levels of the marker CA-125 rose after each of two pregnancies, to a maximum of 13000 U/ml, and stayed elevated. Tissue from another patient showed an abnormal (aneuploid) DNA pattern, whose significance the authors called unclear. Before referral, one patient had an operation removing her omentum and both ovaries; otherwise the authors withheld treatment from all three. Two were well 6 and 7 years after diagnosis. The authors stated that long-term follow-up is still required because biopsies can miss areas and WDPM can turn into true cancer. They concluded that clinicians should know the disease's slow course in order to refrain from aggressive treatment.

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 series (report of three patients)
• Who was studied: Three women with diffuse well-differentiated papillary mesothelioma of the peritoneum, seen at hospitals in Amsterdam and Almelo, the Netherlands, between 1988 and 1995. Patient 1 was 44 in 1989. Patient 2 was 30 and 24 weeks pregnant in 1988. Patient 3 was 36 in February 1995.
• Exposure: No asbestos exposure. The authors reported that none of the three women had a history of exposure to asbestos.
• Main results:
  • Patient 1: after a biopsy suggested probable papillary mesothelioma, a second laparotomy removed the omentum and both ovaries, and multifocal WDPM was confirmed in all removed specimens. This happened before she was referred to the authors' hospital.
  • Patient 1: serum CA-125 was normal (under 30 U/ml) before and after the second laparotomy and remained normal.
  • Patient 1 had no symptoms of disease after 6 years of follow-up without therapy.
  • Patient 2: serum CA-125 was 1170 U/ml during her first pregnancy and reached a maximum of 1660 U/ml 3 months after delivery.
  • Patient 2: after a second delivery (August 1990), serum CA-125 rose gradually to a maximum of 13000 U/ml.
  • Patient 2 remained well after 7 years of follow-up without therapy, although her serum CA-125 values continued to be elevated.
  • Patient 3: all further examinations, including serum CA-125, were negative and remained so.
  • In all 3 patients, electron microscopy showed many microvilli and desmosomes, which the authors took as confirming mesothelial origin.
  • Mean nuclear area was 27.4 square micrometres (standard deviation 5.1) in patient 1 and 36.5 square micrometres (standard deviation 8.4) in patient 2. The authors described these values as low and, in their experience, an indication of benign behaviour.
  • DNA flow cytometry showed a diploid (normal) pattern in patient 1 and an aneuploid pattern with a DNA index of 1.24 in patient 3.
  • CA-125 and EMA staining of tissue was negative in patients 1 and 2 and positive in patient 3.
  • The authors withheld treatment during follow-up and were able to follow 2 patients for a long period. This came after patient 1's earlier surgery.
• The authors' conclusion: The authors concluded that clinicians should be aware of this disease, its clinical features and its indolent course, in order to refrain from an aggressive therapeutic approach.
• Limitations the authors state:
  • Long-term follow-up is required because of possible sampling errors in biopsy material and because WDPM can dedifferentiate to true cancer.
  • The significance of the aneuploid DNA pattern in patient 3 is not clear.
  • Nuclear measurement could not be done for patient 3, because only frozen material was available.
  • DNA flow cytometry could not be done for patient 2, because no adequate material was available.
  • The negative CA-125 tissue staining in patient 2, despite her very high blood levels, might be an artefact of formalin fixation of material from other hospitals.

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: Well-Differentiated Papillary Mesothelioma, Peritoneum, CA-125, Mesothelioma.

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• Well-differentiated papillary mesothelioma of the peritoneum is genetically defined by mutually exclusive mutations in TRAF7 and CDC42 — M. Stevers, J.T. Rabban, et al. (2019)
• Well-differentiated papillary mesothelioma of the female peritoneum: a clinicopathologic study of 26 cases — A. Malpica, S. Sant'Ambrogio, et al. (2012)
• Well-differentiated papillary mesothelioma of the peritoneum: a pathological analysis and review of the literature — A.V. Hoekstra, M.W. Riben, et al. (2005)
• Therapeutic strategies for well-differentiated papillary mesothelioma of the peritoneum — Y.K. Lee, H.J. Jun, et al. (2013)
• Heterozygous loss of NF2 is an early molecular alteration in well-differentiated papillary mesothelioma of the peritoneum — H. Nemoto, G. Tate, et al. (2012)

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