Placental-like alkaline phosphatase reactivity in human tumors: an immunohistochemical study of 520 cases

Our plain-English summary of Placental-like alkaline phosphatase reactivity in human tumors: an immunohistochemical study of 520 cases, by M.R. Wick, P.E. Swanson, J.C. Manivel (Human Pathology, 1987).

The study

• Authors: M.R. Wick, P.E. Swanson, J.C. Manivel
• Journal: Human Pathology
• Published: 1987;18(9):946-54
• Cited by: 89 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Placental-like alkaline phosphatase (PLAP) activity has been reported in various human neoplasms of both somatic and germ cell types. The expression of PLAP was examined with a polyclonal antibody and the immunoperoxidase technique in formalin-fixed, paraffin-embedded sections of 37 germ cell neoplasms and 483 somatic tumors. The expression of keratin and epithelial membrane antigen (EMA) was concurrently assessed to determine whether these stains were helpful in distinguishing germ cell neoplasms from somatic tumors that might mimic them microscopically. All germ cell lesions were reactive for PLAP, but so were 62 somatic carcinomas, usually in female müllerian, intestinal, and lung cancers and less often in carcinomas of the breast and kidney. PLAP-reactive somatic tumors exhibited EMA and keratin positivity in the absence of prior protease digestion, whereas germ cell neoplasms failed to do so. Malignant mesotheliomas were nonreactive for PLAP, as were carcinomas of the nasopharynx, adrenals, liver, pancreas, stomach, prostate, and urinary bladder. PLAP is a highly sensitive but nonspecific immunohistologic marker of germ cell differentiation. However, non-protease-enhanced stains for keratin and EMA allow separation of germ cell and somatic carcinomas, despite their shared capacity for PLAP expression. In somatic neoplasms, PLAP immunoreactivity might be of potential use in predicting possible primary sources for metastatic tumors of unknown origin.

In plain English

This 1987 laboratory study did not examine asbestos or any exposure. It tested whether staining tumor tissue for the enzyme placental-like alkaline phosphatase (PLAP) helps tell tumor types apart. The authors stained 520 archived tumors (37 germ cell, 483 somatic) for PLAP, keratin and epithelial membrane antigen (EMA). All germ cell tumors stained for PLAP, as did 62 somatic carcinomas, mostly female müllerian (genital-tract), intestinal and lung cancers. PLAP-positive somatic carcinomas stained for EMA; germ cell tumors did not, except primitive somatic tissue in one immature teratoma. None of six pleural malignant mesotheliomas stained for PLAP, versus 16 per cent of pulmonary and 60 per cent of serous ovarian adenocarcinomas. These mesotheliomas also lacked the Leu M1 marker, found in 41 of 50 peripheral pulmonary adenocarcinomas. The authors concluded that PLAP, EMA and keratin stains done without protease digestion together help separate germ cell tumors from somatic carcinomas. They suggested PLAP staining may contribute to distinguishing mesothelioma from lung or ovarian adenocarcinoma spread to the pleura. They noted their results are hard to compare with earlier studies using different antibodies.

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: Immunohistochemical (tissue-staining) study of archived tumor specimens
• Who was studied: 520 formalin-fixed, paraffin-embedded tumor specimens from the University of Minnesota surgical pathology files: 37 germ cell tumors and 483 somatic tumors, including 6 malignant epithelial mesotheliomas of the pleura. Collection dates are not given.
• Exposure: Not studied. The article does not mention asbestos or any patient exposure history. It evaluates laboratory stains on tumor tissue.
• Main results:
  • All germ cell tumors were PLAP-positive, and so were 62 somatic carcinomas, usually female müllerian, intestinal and lung cancers and less often breast and kidney carcinomas.
  • All PLAP-positive somatic carcinomas stained for EMA. The text says germ cell tumors did not, but Table 1 marks the single immature teratoma as EMA-positive in its primitive somatic tissues.
  • Table 1 footnote explaining the immature teratoma's EMA and PLAP marking: positivity in primitive somatic tissues.
  • Without protease digestion, PLAP-positive somatic carcinomas stained for keratin. Seminomas and embryonal carcinomas either lacked keratin or showed it only after protease treatment. Choriocarcinoma was the exception among germ cell tumors and stained for keratin without protease.
  • None of the 6 pleural malignant mesotheliomas stained for PLAP. By comparison, 16 per cent of pulmonary adenocarcinomas and 60 per cent of serous ovarian adenocarcinomas did.
  • All 6 pleural malignant mesotheliomas lacked the Leu M1 antigen, which was present in 41 of 50 peripheral pulmonary adenocarcinomas.
  • No carcinomas of the nasopharynx, adrenal gland, liver, pancreas, stomach, prostate or urinary bladder in the study stained for PLAP.
  • The authors suggested that PLAP staining may contribute to distinguishing primary malignant mesothelioma from adenocarcinomas of the lung or ovary that have spread to the pleura.
• The authors' conclusion: The authors concluded that staining for PLAP, together with stains for EMA and for keratin (compared with and without protease digestion), helps distinguish germ cell tumors from somatic carcinomas that look similar under the microscope.
• Limitations the authors state:
  • The authors state that their results are difficult to compare with earlier studies because those studies used different antibodies and detection methods.

Topics

Medical terms in this study, explained in our Lexicon: Placental Alkaline Phosphatase (PLAP), Neoplasm, Epithelial Membrane Antigen (EMA), Carcinoma, Lung Cancer, Malignant Mesothelioma.

Related studies

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• Solitary fibrous tumor of the pleura. An immunohistochemical, electron microscopic and tissue culture study of a tumor producing insulin-like growth factor I in a patient with hypoglycemia — E.H. Strøm, F. Skjørten, et al. (1991)
• The distribution of vimentin and keratin in epithelial and nonepithelial neoplasms. A comprehensive immunohistochemical study on formalin- and alcohol-fixed tumors — N. Azumi, H. Battifora (1987)
• Immunohistochemical distribution of tubulin beta II in human normal and neoplastic tissues — E. Oda, Y. Nakamura, et al. (2005)
• Expression of the Wilms' tumor gene WT1 in human malignant mesothelioma cell lines and relationship to platelet-derived growth factor A and insulin-like growth factor 2 expression — A.W. Langerak, K.A. Williamson, et al. (1995)
• Immunohistochemical reactivity in mesothelioma and adenocarcinoma: a stepwise logistic regression analysis — A. Dejmek, A. Hjerpe (1994)

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