Immunohistochemical differentiation of sarcomatoid mesotheliomas from other spindle cell neoplasms

Our plain-English summary of Immunohistochemical differentiation of sarcomatoid mesotheliomas from other spindle cell neoplasms, by P.T. Cagle, L.D. Truong, V.L. Roggli, et al (American Journal of Clinical Pathology, 1989).

The study

• Authors: P.T. Cagle, L.D. Truong, V.L. Roggli, S.D. Greenberg
• Journal: American Journal of Clinical Pathology
• Published: 1989;92(5):566-71
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002480).

Abstract

A sizable proportion of pleural malignant mesotheliomas are sarcomatoid (22%) or biphasic (24%) and may need to be distinguished from other spindle cell neoplasms that occur as primary or metastatic tumors of the chest wall or lungs. To determine the utility of immunohistochemistry in the differentiation of sarcomatoid malignant mesotheliomas from other spindle cell neoplasms, the authors studied the immunostaining patterns of nine antibodies in four sarcomatoid mesotheliomas, one desmoplastic mesothelioma, two epithelial mesotheliomas, four spindle cell squamous carcinomas, and eight sarcomas of various differentiation. Three of the four sarcomatoid mesotheliomas and the desmoplastic mesothelioma had positive results for cytokeratin, which distinguishes them from sarcomas but not from spindle cell squamous carcinomas. The immunostaining pattern of 14 examples of benign spindle cell mesothelial proliferation was similar to that of the sarcomatoid mesotheliomas, which supports the theory that these tumors are mesothelial in origin. Although other antibodies occasionally may be helpful, depending on the differentiation of the sarcoma, cytokeratin immunostaining appears to be the best method to discriminate sarcomatoid mesotheliomas from sarcomas.

In plain English

This was a small laboratory study. It tested whether antibody staining of tumor tissue (immunohistochemistry) could tell sarcomatoid mesothelioma, a spindle-cell form of the cancer, apart from other spindle-cell tumors. The authors stained stored tissue with nine antibodies. The samples were four sarcomatoid, one desmoplastic and two epithelial mesotheliomas, all of the pleura, plus four spindle cell squamous carcinomas, eight sarcomas, and 14 samples of benign spindle-cell mesothelial growth. Known asbestos exposure was recorded for four of the five patients with sarcomatoid or desmoplastic mesothelioma. No fiber types were given. Three of the four sarcomatoid mesotheliomas, and the desmoplastic one, stained strongly for cytokeratin and vimentin. All 14 benign samples were also cytokeratin positive, and the authors said this similarity suggests that sarcomatoid mesotheliomas are mesothelial in origin. None of the eight sarcomas stained for cytokeratin, but all four spindle cell squamous carcinomas did. The authors concluded that cytokeratin staining is the best marker for distinguishing sarcomatoid mesothelioma from sarcoma. They added that staining cannot separate it from spindle cell squamous carcinoma.

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 comparing antibody staining patterns in stored surgical and autopsy tumor tissue
• Who was studied: Tissue from 4 sarcomatoid mesotheliomas (3 pure and 1 biphasic with a predominantly sarcomatoid pattern), 1 desmoplastic mesothelioma and 2 epithelial mesotheliomas, all pleural. Also tissue from 4 malignant fibrous histiocytomas, 4 spindle cell squamous carcinomas, 2 leiomyosarcomas, 1 neurofibrosarcoma, 1 osteosarcoma, and 14 specimens of benign reactive mesothelial proliferation made up mostly of spindle cells.
• Exposure: The study examined nine antibody stains, not asbestos exposure. Table 1 records known asbestos exposure as present in 4 of the 5 patients with sarcomatoid or desmoplastic mesothelioma and absent in 1 (case 2). No fiber types, products or jobs are given.
• Main results:
  • Sarcomatoid mesotheliomas: 3 of 4 were positive for cytokeratin and 3 of 4 for vimentin. The desmoplastic mesothelioma was positive for both (1/1). In these tumors, 90% of the malignant cells stained strongly for both markers in all but one sarcomatoid mesothelioma.
  • The desmoplastic mesothelioma was also positive for CEA (1/1), but only focally, in its epithelial areas. The mesotheliomas were negative for the other markers tested.
  • Benign spindle cell mesothelial proliferations: 14/14 were positive for cytokeratin and 12/14 for vimentin, a pattern similar to the malignant mesotheliomas. The authors said this similarity suggests that sarcomatoid mesotheliomas are mesothelial in origin.
  • All eight sarcomas were positive for vimentin. None were positive for cytokeratin (Table 3: 0/4 malignant fibrous histiocytomas, 0/2 leiomyosarcomas, 0/1 neurofibrosarcoma, 0/1 osteosarcoma). Some stained for other markers depending on their type: both leiomyosarcomas for desmin (2/2), and malignant fibrous histiocytomas for alpha-1-antichymotrypsin (3/4), CEA (2/4) and lysozyme (1/4).
  • Spindle cell squamous carcinomas: 4/4 were positive for both cytokeratin and vimentin, the same pattern as the sarcomatoid mesotheliomas.
• The authors' conclusion: The authors concluded that, although other antibodies may sometimes help depending on the type of sarcoma, cytokeratin positivity is the best immunohistochemical marker for distinguishing sarcomatoid mesothelioma from sarcoma.
• Limitations the authors state:
  • The authors state that the staining pattern cannot distinguish sarcomatoid mesothelioma from spindle cell squamous carcinoma.

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, Mesothelioma, Spindle Cell, Neoplasm, Malignant Mesothelioma, Biphasic Mesothelioma, Immunohistochemistry, Desmoplastic Mesothelioma.

Related studies

• Unusual primary lung neoplasms: spindle cell and undifferentiated lung carcinomas expressing only vimentin — S.P. Hammar, K.O. Hallman (1990)
• The differential diagnosis between pleural sarcomatoid mesothelioma and spindle cell/pleomorphic (sarcomatoid) carcinomas of the lung: evidence-based guidelines from the International Mesothelioma Panel and the MESOPATH National Reference Center — A.M. Marchevsky, N. LeStang, et al. (2017)
• Synovial sarcoma of the pleura and its differentiation from other primary pleural tumours: a clinicopathological and immunohistochemical review of three cases — A.G. Nicholson, P. Goldstraw, et al. (1998)
• Deep-learning based classification distinguishes sarcomatoid malignant mesotheliomas from benign spindle cell mesothelial proliferations — J.R. Naso, A.B. Levine, et al. (2021)
• Nuclear Brachyury Expression Is Consistent in Chordoma, Common in Germ Cell Tumors and Small Cell Carcinomas, and Rare in Other Carcinomas and Sarcomas: An Immunohistochemical Study of 5229 Cases — M. Miettinen, Z. Wang, et al. (2015)
• Immunohistochemical analysis still has a limited role in the diagnosis of malignant mesothelioma. A study of thirteen antibodies — F. Roberts, C.M. Harper, et al. (2001)

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