A comparative immunohistochemical study of peritoneal and ovarian serous tumors, and mesotheliomas

Our plain-English summary of A comparative immunohistochemical study of peritoneal and ovarian serous tumors, and mesotheliomas, by N. Khoury, U. Raju, J.D. Crissman, et al (Human Pathology, 1990).

The study

• Authors: N. Khoury, U. Raju, J.D. Crissman, R.J. Zarbo, K.A. Greenawald
• Journal: Human Pathology
• Published: 1990;21(8):811-9
• Cited by: 60 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The distinction between serous neoplasms of the peritoneum in women and conventional mesothelioma can be difficult. In order to determine any significant immunohistochemical differences, formalin-fixed, paraffin-embedded sections of 10 peritoneal serous tumors (PST), 10 ovarian serous tumors (OST), and 10 epithelial mesotheliomas were evaluated with a panel of 10 antibodies directed against carcinoembryonic antigen (CEA: polyclonal, monoclonal), high molecular weight keratin (34 beta E12), low molecular weight keratin (35 beta H11), Leu-M1, TAG-72 (monoclonal antibody B72.3), human milk fat globulin (HMFG-2), vimentin, placental alkaline phosphatase (PLAP), and S-100 protein. The antibodies CEA, Leu-M1, and B72.3 had the most discriminatory value in differentiating serous tumors from mesothelioma. Eighty-five percent of PSTs and OSTs (17 of 20) were positive with CEA, Leu-M1, and/or B72.3. None of the mesotheliomas stained for CEA or Leu-M1; three mesotheliomas had very focal positivity with B72.3 (1% or less). Vimentin, PLAP, HMGF-2, keratin, and S-100 had no significant discriminatory value. Epithelial mucin was present in 80% of serous tumors, while the mesotheliomas lacked epithelial mucin. Leu-M1, CEA, and/or B72.3 positivity in a peritoneal tumor supports a diagnosis of serous tumor. However, since some PST do not stain for any of the three antibodies and the focal nature of positive reactions in some cases may be difficult to interpret, exclusion of mesotheliomas is enhanced by the use of mucin stains.

In plain English

This laboratory study compared stained tumor tissue to find markers that help pathologists tell apart two tumor types that can look alike: serous tumors of the peritoneum (the abdominal lining) in women, and mesothelioma. The authors tested archived samples from 10 peritoneal serous tumors, 10 ovarian serous tumors and 10 epithelial mesotheliomas with a panel of 10 antibodies and with mucin stains. None of the mesotheliomas stained for CEA or Leu-M1. Among the serous tumors, 35% were CEA-positive and 30% were Leu-M1-positive. After pepsin pretreatment, B72.3 stained 13 of 20 serous tumors (65%). It also stained very few cells, 1% or less, in three mesotheliomas. Overall, 85% of serous tumors were positive for at least one of these three antibodies. Epithelial mucin was found in seven peritoneal and nine ovarian serous tumors but in no mesothelioma. The authors judged HMFG-2 and PLAP not useful. The authors concluded that CEA, Leu-M1 and/or B72.3 positivity supports a serous tumor diagnosis and that mucin stains help exclude mesothelioma. They cautioned that negative results should be interpreted carefully.

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: comparative immunohistochemical laboratory study of archived, formalin-fixed, paraffin-embedded tumor tissue
• Who was studied: Tissue from 10 peritoneal serous tumors (in women aged 19 to 75), 10 ovarian serous tumors and 10 predominantly epithelial-type mesotheliomas (eight men, two women; four peritoneal, six pleural). The time period of the cases is not stated.
• Exposure: Not an asbestos exposure study. The tissues were tested with 10 antibodies (polyclonal and monoclonal CEA, Leu-M1, B72.3, high and low molecular weight keratin, HMFG-2, vimentin, PLAP, S-100) and with mucin stains.
• Main results:
  • All 10 mesotheliomas were negative for CEA and Leu-M1. Among the 20 serous tumors, 35% were CEA-positive and 30% were Leu-M1-positive.
  • With pepsin predigestion, B72.3 was positive in 13 of 20 serous tumors (65%), focal in three of them.
  • Three mesotheliomas had very focal B72.3 positivity in pepsin-treated sections: much less than 1% of cells in two cases and 1% in one case.
  • 85% of serous tumors were positive for at least one of CEA, Leu-M1 or B72.3.
  • Epithelial mucin was found in 7 of 10 peritoneal and 9 of 10 ovarian serous tumors (80% overall). The mesotheliomas lacked epithelial mucin.
  • 90% of serous tumors were positive for at least one of the three antibodies or the mucin stains.
  • High molecular weight keratin stained 8 of 10 mesotheliomas strongly and diffusely, and two were negative. It also stained two peritoneal and three ovarian serous tumors, more weakly.
  • PLAP was positive in 25% of serous tumors and absent in mesotheliomas. The authors considered this too small a share to be of practical value.
  • The authors judged HMFG-2 not useful for this diagnostic distinction.
  • Vimentin was positive in only four mesotheliomas, each with a spindle cell component. It was also positive, focally, in 30% of peritoneal and 30% of ovarian serous tumors.
  • S-100 was negative in all but two of the serous tumors and in all mesotheliomas.
• The authors' conclusion: The authors concluded that Leu-M1, CEA and/or B72.3 positivity in a peritoneal tumor supports a diagnosis of serous tumor, and that mucin stains improve exclusion of mesothelioma. They added that negative results from any of these ancillary tests should be interpreted with caution.
• Limitations the authors state:
  • Some peritoneal serous tumors did not stain with any of the three antibodies, and focal positive reactions can be hard to interpret.
  • Mucin stains alone may be inconclusive, because some serous tumors show no recognizable epithelial mucin in the samples examined.
  • CEA stains showed nonspecific staining in necrotic areas, inflammatory cells and psammoma bodies, so they had to be interpreted carefully.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Neoplasm, Peritoneum, Carcinoembryonic Antigen (CEA), Monoclonal, B72.3 (TAG-72), Monoclonal Antibody, Placental Alkaline Phosphatase (PLAP).

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