Keratin protein immunoreactivity of sarcomatoid and mixed types of diffuse malignant mesothelioma: an immunoperoxidase study of 30 cases

Our plain-English summary of Keratin protein immunoreactivity of sarcomatoid and mixed types of diffuse malignant mesothelioma: an immunoperoxidase study of 30 cases, by A.G. Montag, G.S. Pinkus, J.M. Corson (Human Pathology, 1988).

The study

• Authors: A.G. Montag, G.S. Pinkus, J.M. Corson
• Journal: Human Pathology
• Published: 1988;19(3):336-42
• Cited by: 48 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To define the role of keratin protein immunohistochemistry in the pathologic diagnosis of the sarcomatoid type of diffuse malignant mesothelioma (DMM), we examined 30 DMM (16 pure sarcomatoid type and 14 mixed sarcomatoid-epithelial type) by an indirect immunoperoxidase technique using three commercially available antibodies to keratin proteins. The sarcomatoid (spindle-cell) areas of all 30 cases of sarcomatoid DMM were immunoreactive for keratin proteins. In 14 of 16 cases of sarcomatoid DMM, 50% or more of the tumor cells were reactive with one or more antibodies; however, polyclonal bovine muzzle and monoclonal AE1/AE3 antibodies were distinctly superior to polyclonal human callus keratin antibody in the detection of spindle tumor cells. In contrast with the staining patterns observed for DMM, 39 spindle-cell malignancies and tumor-like processes of 10 histogenetic types were unreactive with the three antibodies. Those spindle-cell tumors and reactive mesothelial proliferations that may enter into the differential diagnosis of sarcomatoid DMM are discussed. We conclude that keratin protein immunohistochemistry is a sensitive and highly useful method for the pathologic diagnosis of the sarcomatoid type of DMM and its distinction from other spindle-cell neoplasms.

In plain English

This Boston laboratory study tested whether keratin staining helps diagnose sarcomatoid (spindle-cell) diffuse malignant mesothelioma. The authors stained 30 mesotheliomas, 16 pure sarcomatoid and 14 mixed sarcomatoid-epithelial, with up to three keratin antibodies, but not every case received all three. They compared these with 39 other spindle-cell tumors and tumor-like processes of 10 types. Spindle tumor cells in every mesothelioma stained for keratin. In 15 of the 16 sarcomatoid cases, more than 50% of tumor cells stained with one or more antibodies. The human callus antibody was less sensitive: it stained 10% or fewer tumor cells in 6 of 16 sarcomatoid cases, versus 1 of 16 (bovine muzzle) and 2 of 13 (AE1/AE3). None of the 39 comparison tumors stained. The authors concluded that keratin staining is a sensitive and useful diagnostic method. They cautioned that some other spindle-cell tumors and normal and reactive mesothelial cells are keratin positive. Assuming a 1 by 0.1 cm needle core, they estimated from their staining patterns that as many as 10 to 15% of needle biopsies potentially could be falsely negative. Asbestos exposure was not studied.

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: Laboratory (immunohistochemistry) study of archived tumor tissue, comparing mesothelioma cases with control spindle-cell tumors
• Who was studied: 30 diffuse malignant mesothelioma cases (16 pure sarcomatoid, 14 mixed type) chosen from more than 200 in the files of Brigham and Women's Hospital, Boston. Patients were 22 male and 8 female, aged 32 to 85 (median 61). There were 27 pleural and 3 peritoneal specimens; one case was from 1962 and the rest from 1979 to 1986. Controls were 39 other spindle-cell tumors and tumor-like processes from 1982 to 1986.
• Exposure: No asbestos or other exposure was studied. The article examined tumor staining with three keratin antibodies: polyclonal human callus, polyclonal bovine muzzle, and monoclonal AE1/AE3. Not all cases were tested with AE1/AE3.
• Main results:
  • All 16 sarcomatoid-type mesotheliomas stained for keratin proteins, and all but 1 stained with all three antibodies.
  • In 15 of the 16 sarcomatoid cases, more than 50% of tumor cells stained with one or more antibodies.
  • Among sarcomatoid cases, the human callus antibody stained 10% or fewer tumor cells in 6 of 16 cases (38%).
  • By comparison, the bovine muzzle antibody stained 10% or fewer tumor cells in 1 of 16 sarcomatoid cases (6%), and the AE1/AE3 antibody did so in 2 of 13 cases tested (15%).
  • In all 14 mixed-type cases, the sarcomatoid areas stained with both polyclonal antibodies. Median stained cells were 40% (human callus) and 75% (bovine muzzle) in sarcomatoid areas, and 90% and 97% in epithelial areas.
  • In the 39 control spindle-cell tumors and tumor-like processes, tumor cells did not stain with any of the three antibodies.
• The authors' conclusion: The authors concluded that keratin protein staining is a sensitive and highly useful method for diagnosing the sarcomatoid type of diffuse malignant mesothelioma and for distinguishing it from other spindle-cell tumors.
• Limitations the authors state:
  • In the mixed-type cases, only a few were stained with the AE1/AE3 antibody because there was not enough tissue.
  • From the distribution of stained tumor cells in their cases, and assuming a 1 by 0.1 cm biopsy core, the authors estimated that as many as 10 to 15% of needle biopsies potentially could give a false-negative result, even with the more sensitive antibodies. This was an estimate, not an observed rate.
  • Some spindle-cell tumors other than mesothelioma can express keratin, and normal and reactive mesothelial cells are keratin positive, so results need careful interpretation.

Topics

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

Medical terms in this study, explained in our Lexicon: Sarcomatoid, Malignant Mesothelioma, Immunohistochemistry, Monoclonal, Differential Diagnosis, Neoplasm.

Related studies

• Keratin proteins and carcinoembryonic antigen in lung carcinoma: an immunoperoxidase study of fifty-four cases, with ultrastructural correlations — J.W. Said, G. Nash, et al. (1983)
• Immunoperoxidase localization of keratin proteins, carcinoembryonic antigen, and factor VIII in adenomatoid tumors: evidence for a mesothelial derivation — J.W. Said, G. Nash, et al. (1982)
• Distinct keratin patterns demonstrated by immunoperoxidase staining of adenocarcinomas, carcinoids, and mesotheliomas using polyclonal and monoclonal anti-keratin antibodies — H.J. Kahn, P.S. Thorner, et al. (1986)
• Keratin and epithelial membrane antigen immunoreactivity in nonneoplastic fibrous pleural lesions: implications for the diagnosis of desmoplastic mesothelioma — J.I. Epstein, R.E. Budin (1986)
• Immunoreactivity for calretinin and keratins in desmoid fibromatosis and other myofibroblastic tumors: a diagnostic pitfall — S. Barak, Z. Wang, et al. (2012)
• Immunohistochemical staining for vimentin and keratin in malignant mesothelioma — A. Churg (1985)

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