Keratin and epithelial membrane antigen immunoreactivity in nonneoplastic fibrous pleural lesions: implications for the diagnosis of desmoplastic mesothelioma

Our plain-English summary of Keratin and epithelial membrane antigen immunoreactivity in nonneoplastic fibrous pleural lesions: implications for the diagnosis of desmoplastic mesothelioma, by J.I. Epstein, R.E. Budin (Human Pathology, 1986).

The study

• Authors: J.I. Epstein, R.E. Budin
• Journal: Human Pathology
• Published: 1986;17(5):514-9
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The histologic distinction between desmoplastic mesothelioma and reactive fibrosis and between biphasic desmoplastic mesothelioma and pleural metastases with desmoplasia can be difficult. The presence of such epithelial markers as keratin and epithelial membrane antigen (EMA) within the fibrous areas of a pleural lesion might be construed as evidence in support of the diagnosis of desmoplastic mesothelioma. To test this hypothesis ten desmoplastic mesotheliomas were studied with monoclonal antisera to keratin and EMA and compared with ten hyaline pleural plaques, 11 pleural scars, five benign localized fibrous mesotheliomas, and eight desmoplastic pleural metastases. Although the hyalinized fibrous areas within the desmoplastic mesotheliomas stained with keratin (ten of ten) and EMA (five of ten), the following reactive fibrous pleural lesions were also positive: plaques (four of ten keratin-positive, five of ten EMA-positive); scars (six of 11 keratin-positive, four of 11 EMA-positive); and fibrosis induced by metastases (six of eight keratin-positive, one of eight EMA-positive). Benign localized fibrous mesotheliomas were keratin- and EMA-negative. This study suggests that both benign and malignant fibrous pleural lesions may be of mesothelial origin and demonstrates the need to determine by histologic criteria whether the spindle cell component is benign or malignant before assessing the significance of its keratin or EMA immunoreactivity. The lack of keratin and EMA staining in benign localized fibrous mesotheliomas might be of use in distinguishing benign localized cellular fibrous mesotheliomas from sarcomatous mesotheliomas.

In plain English

This laboratory study at The Johns Hopkins Hospital tested whether two markers of epithelial cells, keratin and epithelial membrane antigen (EMA), could help distinguish desmoplastic mesothelioma (a pleural mesothelioma more than half made of sparse-celled fibrous tissue) from non-cancerous pleural scarring or from cancers that had spread to the pleura. The authors stained tissue from ten desmoplastic mesotheliomas and compared it with ten hyaline pleural plaques, 11 pleural fibrous lesions not associated with tumor, five benign localized fibrous mesotheliomas and eight cancers spread to the pleura. Fibroblast-like cells in the fibrous areas stained for keratin in all ten mesotheliomas and for EMA in five. Non-cancerous tissue also stained. Keratin stained four of ten plaques and six of 11 fibrous lesions. EMA stained five of ten plaques and four of 11 lesions. Keratin also stained the fibrous reaction around six of eight metastases. Benign localized fibrous mesotheliomas and 16 fibrous lesions away from the pleura did not stain. The authors concluded that these markers in benign fibrous pleural tissue are not evidence of desmoplastic mesothelioma. 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 pathology study comparing immunohistochemical staining (keratin and epithelial membrane antigen) of desmoplastic mesotheliomas with non-cancerous and other fibrous pleural lesions
• Who was studied: Ten desmoplastic mesotheliomas from the Johns Hopkins Hospital pathology files (Baltimore, Maryland). Comparison tissues were ten hyaline pleural plaques obtained at autopsy, 11 pleural fibrous processes (five hyaline scars, two cellular scars, four fibrinofibrous scars), five surgically excised benign localized fibrous mesotheliomas, and eight scirrhous metastases to the pleura. Also included were tumor-associated fibrous tissue away from the pleura in six of these metastatic cases, plus ten more tumors not involving the pleura. Years of the cases are not given.
• Exposure: Not an exposure study: the article does not report asbestos or any other exposure for these cases. The tissues were stained with monoclonal antibodies to keratin and epithelial membrane antigen (EMA).
• Main results:
  • Desmoplastic mesotheliomas: keratin stained the bland fibroblast-like cells in the hyalinized areas of all ten mesotheliomas.
  • Desmoplastic mesotheliomas: EMA stained fibroblastic cells in the desmoplastic areas of five of the ten (one sarcomatous, three mixed, one plaque-like).
  • Pleural hyaline plaques: keratin stained fibroblastic cells in four of ten plaques.
  • Pleural hyaline plaques: EMA stained fibroblastic cells in five of ten plaques, two of which were also keratin-positive.
  • Pleural fibrous lesions not associated with tumor: six of 11 were keratin-positive.
  • Pleural fibrous lesions not associated with tumor: EMA stained four of them (one cellular, one fibrinofibrous and two hyaline scars).
  • Cancers spread to the pleura: the fibroblastic cells of the fibrous response were keratin-positive in six of eight cases.
  • Cancers spread to the pleura: EMA stained the fibroblastic response in one of eight cases, and that case was keratin-negative.
  • Fibrous tissue around tumors away from the pleura (six of the metastatic cases plus ten other scirrhous tumors) showed no keratin or EMA staining.
  • Benign localized fibrous mesotheliomas: none of the five stained for keratin or EMA.
  • In several cases of non-cancerous pleural fibrosis, transitions were traced from marker-positive surface mesothelial cells to deeper marker-positive fibroblastic cells. The authors suggested that some, and possibly all, fibrous lesions on the pleural surface come from mesothelium.
• The authors' conclusion: The authors concluded that keratin or EMA staining in benign-appearing fibrous tissue on the pleura is not evidence of desmoplastic mesothelioma. Such staining may represent non-specific fibrosis or a desmoplastic metastasis. Whether the spindle cells are benign or malignant must first be judged by histologic criteria.

Topics

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

Medical terms in this study, explained in our Lexicon: Epithelial Membrane Antigen (EMA), Desmoplastic Mesothelioma, Fibrosis, Biphasic Mesothelioma, Monoclonal, Pleural Plaques, Mesothelioma, Spindle Cell.

Related studies

• The distinction of adenocarcinoma from malignant mesothelioma in cell blocks of effusions: the role of routine mucin histochemistry and immunohistochemical assessment of carcinoembryonic antigen, keratin proteins, epithelial membrane antigen, and milk fat globule-derived antigen — E.S. Cibas, J.M. Corson, et al. (1987)
• Keratin protein immunoreactivity of sarcomatoid and mixed types of diffuse malignant mesothelioma: an immunoperoxidase study of 30 cases — A.G. Montag, G.S. Pinkus, et al. (1988)
• 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)
• Immunoreactivity for calretinin and keratins in desmoid fibromatosis and other myofibroblastic tumors: a diagnostic pitfall — S. Barak, Z. Wang, et al. (2012)
• Value of p63 and cytokeratin 5/6 as immunohistochemical markers for the differential diagnosis of poorly differentiated and undifferentiated carcinomas — O. Kaufmann, E. Fietze, et al. (2001)

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