Malignant mesothelioma of the peritoneum: case reports and immunohistochemical findings including Ki-67 expression

Our plain-English summary of Malignant mesothelioma of the peritoneum: case reports and immunohistochemical findings including Ki-67 expression, by H. Hirano, T. Fujisawa, K. Maekawa, et al (Medical Molecular Morphology, 2010).

The study

• Authors: H. Hirano, T. Fujisawa, K. Maekawa, E. Ohkubo, A. Okimura, K. Kuribayashi, T. Nakano, K. Nakasho, T. Nishigami
• Journal: Medical Molecular Morphology
• Published: 2010;43(1):53-9
• Type of article: Case report
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A malignant mesothelioma (MM) is an aggressive neoplasm, although some patients have shown long-term survival, and factors related to survival remain uncertain. We present three cases of MM of the peritoneum including autopsy results, in which factors related to long-term survival were investigated. Case 1 was a 69-year-old man who died 6 years after the initial diagnosis. In case 2, a 67-year-old woman came to us with abdominal distention and, despite chemotherapy, died 9 months after the initial diagnosis. The patient in case 3 was a 68-year-old man who also had abdominal distention and died 9 months after the initial diagnosis. We studied the clinicopathological appearance and performed immunohistochemical staining including Ki-67 labeling index (Ki-67 LI) in primary and metastatic sites of these cases. The histological findings of case 1 indicated epithelioid type; case 2 and 3 were of biphasic type. Immunohistochemical results were consistent with MM. The Ki-67 LI value for both primary and metastatic sites of case 1 was significantly lower than those in cases 2 and 3. We consider Ki-67 LI to be a useful prognostic indicator for MM of the peritoneum.

In plain English

This case report described three patients with malignant mesothelioma of the peritoneum (the abdominal lining), all examined after death. A 69-year-old man died 6 years after diagnosis. A 67-year-old woman and a 68-year-old man each died about 9 months after diagnosis or admission. The 68-year-old man had a 10-year history of asbestos exposure and was the only one with pleural plaque and asbestos bodies in the lungs. The 69-year-old man recalled no obvious asbestos exposure but had been exposed at work to fine particles that may have included asbestos. The woman recalled no obvious exposure. The long survivor's tumor was epithelioid type. The other two were biphasic, with necrosis and a sarcomatous component. The Ki-67 labeling index is the share of tumor cells showing a marker of proliferation. It was significantly lower in the long survivor (0.85% in the main tumor) than in the other two (42.9% and 5.5% in the epithelioid part of their main tumors). The authors considered Ki-67 a useful prognostic indicator for peritoneal mesothelioma. They also noted other factors may be needed to explain poor prognosis.

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 of three patients, with autopsy findings and immunohistochemical staining, including the Ki-67 labeling index
• Who was studied: Three patients with malignant mesothelioma of the peritoneum, all autopsied, from hospitals in Hyogo, Japan: a 69-year-old man, a 67-year-old woman and a 68-year-old man. Dates are not given.
• Exposure: Case 3 (68-year-old man) had a 10-year history of asbestos exposure. Case 1 (69-year-old man) had no memory of obvious asbestos exposure but had been exposed at work to fine particles that may have included asbestos. Case 2 (67-year-old woman) had no recollection of obvious asbestos exposure. No fiber types are named.
• Main results:
  • Case 1 (epithelioid type) had an indolent course compared with cases 2 and 3 (biphasic type). Case 1 died 6 years after diagnosis; cases 2 and 3 died about 9 months after admission or diagnosis.
  • The tumors in cases 2 and 3 showed solid architecture, high-grade nuclei, high mitotic count, necrosis and a sarcomatous component. The tumor in case 1 did not.
  • At autopsy, plaque in the pleura and asbestos bodies in both lungs were found only in case 3. No plaque or asbestos bodies were found in the lungs in cases 1 and 2.
  • Immunohistochemical staining results in all three cases were consistent with malignant mesothelioma.
  • The Ki-67 labeling index was calculated by counting positive nuclei per 100 tumor cells. In both the primary peritoneal tumor and the metastatic sites, it was significantly lower in case 1 than in cases 2 and 3.
  • Case 1, primary peritoneal tumor (epithelioid): Ki-67 labeling index 0.85% plus or minus 0.3%
  • Case 2, primary peritoneal tumor, epithelioid component: Ki-67 labeling index 42.9% plus or minus 11.8%
  • Case 3, primary peritoneal tumor, epithelioid component: Ki-67 labeling index 5.5% plus or minus 1.5%
  • In cases 1 and 3, the Ki-67 labeling index in the metastatic organs was significantly higher than in the peritoneum.
  • In case 2, the Ki-67 labeling index of the sarcomatous component was lower at the metastatic site (23.7%) than in the primary peritoneal tumor (29.2%). The table marks this difference as not significant.
• The authors' conclusion: The authors considered the Ki-67 labeling index a useful prognostic indicator for malignant mesothelioma of the peritoneum. They also suggested that the epithelioid type may tend toward an indolent course.
• Limitations the authors state:
  • Because of the findings in case 2, the authors stated that factors other than Ki-67 may be needed to explain the poor prognosis of peritoneal mesothelioma.
  • The authors stated that survival cannot be accounted for by histological appearance, because some low-grade-looking mesotheliomas behave aggressively.
  • The authors had no information on how far the tumor had spread in case 1 at the time of initial diagnosis.

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: Malignant Mesothelioma, Peritoneum, Ki-67, Neoplasm, Autopsy, Chemotherapy, Immunohistochemistry, Epithelioid.

Related studies

• Malignant mesothelioma of the pericardium: case reports and immunohistochemical studies including Ki-67 expression — H. Hirano, T. Maeda, et al. (2002)
• Pseudomesotheliomatous carcinoma involving pleura and peritoneum: A clinicopathologic and immunohistochemical study of three cases — I.A. Shah, J.R. Salvatore, et al. (1999)
• Prognostic role of CD74, CD10 and Ki-67 immunohistochemical expression in patients with diffuse malignant peritoneal mesothelioma: a retrospective study — Y. Liang, C. Li, et al. (2023)
• 'Mucin-positive' epithelial mesothelioma of the peritoneum: an unusual diagnostic pitfall — D.S. Cook, R.L. Attanoos, et al. (2000)
• Malignant epithelial mesothelioma of the peritoneum: observations on a problem case — B.P. Eyden, S. Banik, et al. (1996)
• 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)

Browse return to medical research.