Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma

Our plain-English summary of Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma, by K. Kushitani, V.J. Amatya, Y. Okada, et al (Histopathology, 2017).

The study

• Authors: K. Kushitani, V.J. Amatya, Y. Okada, Y. Katayama, A.S. Mawas, Y. Miyata, M. Okada, K. Inai, T. Kishimoto, Y. Takeshima
• Journal: Histopathology
• Published: 2017;70(3):375-384
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims: The aims of this study were to clarify the usefulness of immunohistochemistry in the differential diagnosis of epithelioid mesothelioma with a solid growth pattern [solid epithelioid mesothelioma (SEM)] and poorly differentiated squamous cell carcinoma (PDSCC), and to confirm the validity of a specific type of antibody panel. Additionally, we aimed to clarify the pitfalls of immunohistochemical analyses.

Methods And Results: Formalin-fixed paraffin-embedded specimens from 36 cases of SEM and 38 cases of PDSCC were immunohistochemically examined for calretinin, podoplanin (D2-40), Wilms' tumour gene product (WT1), cytokeratin (CK) 5/6, p40, p63, carcinoembryonic antigen (CEA), epithelial-related antigen (MOC31), claudin-4, thyroid transcription factor-1 (TTF-1), and napsin A. WT1 showed the highest diagnostic accuracy (85.1%) as a mesothelial marker, and CEA, p40 and claudin-4 showed higher diagnostic accuracies (95.9%, 94.6%, and 93.2%, respectively) as carcinoma markers. Calretinin (diagnostic accuracy: 75.7%), D2-40 (diagnostic accuracy: 67.6%), CK5/6 (diagnostic accuracy: 63.5%), TTF-1 (diagnostic accuracy: 55.4%) and napsin A (diagnostic accuracy: 52.7%) could not differentiate between SEM and PDSCC. Among these markers, the combination of calretinin and WT1 showed the highest diagnostic accuracy (86.5%) as a positive marker, and the combination of p40 and CEA showed the highest diagnostic accuracy (97.3%) as a negative marker. The combination of CEA and claudin-4 also showed relatively high diagnostic accuracy (94.6%) as a negative marker.

Conclusions: We recommend the combination of WT1 and calretinin as a positive maker, and the combination of CEA and claudin-4 as a negative marker, for differential diagnoses of SEM and PDSCC.

© 2016 John Wiley & Sons Ltd.

In plain English

This Japanese laboratory study tested whether antibody staining (immunohistochemistry) can tell apart two look-alike cancers: epithelioid mesothelioma with a solid growth pattern, and poorly differentiated lung squamous cell carcinoma. The authors examined archived tissue from 36 mesothelioma patients and 38 lung carcinoma patients, collected between 2000 and 2014, using 11 commercially available markers. The study did not measure asbestos exposure; occupational asbestos history was one factor used to confirm the mesothelioma diagnoses. Among single markers, WT1 had the highest diagnostic accuracy as a mesothelioma marker (85.1%), and CEA had the highest of all 11 markers (95.9%). Calretinin, D2-40, CK5/6, TTF-1 and napsin A could not separate the two tumours. Requiring both calretinin and WT1 to be positive gave 86.5% accuracy; counting either as positive gave 74.3%. Requiring both p40 and CEA to be negative gave 97.3% (accepting either gave 93.2%), and requiring both CEA and claudin-4 to be negative gave 94.6%. The authors recommended WT1 plus calretinin and CEA plus claudin-4, preferring claudin-4 to p40 because p40 is rarely expressed in lung adenocarcinoma, which could then be mistaken for mesothelioma.

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: Diagnostic laboratory study: immunohistochemical staining of archived tumour specimens with 11 antibody markers, with sensitivity, specificity, predictive values and diagnostic accuracy calculated for single markers and pairs of markers
• Who was studied: Formalin-fixed paraffin-embedded specimens from 36 patients with solid epithelioid mesothelioma (from pleural biopsy, pleurectomy/decortication, extrapleural pneumonectomy or autopsy) and 38 patients with primary pulmonary poorly differentiated squamous cell carcinoma (from surgical resection), 2000 to 2014, Japan (Hiroshima University). None of the carcinomas showed diffuse pleural growth.
• Exposure: Asbestos exposure was not studied or measured. What was tested were 11 antibody markers: calretinin, D2-40, WT1, CK5/6, p40, p63, CEA, MOC31, claudin-4, TTF-1 and napsin A. Clinical history such as occupational asbestos exposure was one of the factors used to confirm the mesothelioma diagnoses.
• Main results:
  • WT1 was positive in 26 of 36 mesotheliomas (72.2%) and in only 1 of 38 carcinomas. It had a specificity of 97.4% and the highest diagnostic accuracy (85.1%) among the three mesothelioma-positive markers.
  • None of the 36 mesotheliomas stained for CEA, while 92.1% of the carcinomas did. CEA had a sensitivity of 100% and a diagnostic accuracy of 95.9%, the best of all 11 markers.
  • Calretinin was positive in 33 of 36 mesotheliomas (91.7%) but also in 15 of 38 carcinomas (39.5%). Its specificity was 60.5% and its diagnostic accuracy 75.7%.
  • D2-40 had a sensitivity of 97.2% for mesothelioma, but a specificity of 39.5% and a diagnostic accuracy of 67.6%.
  • Calretinin (75.7%), D2-40 (67.6%), CK5/6 (63.5% in the abstract; Table 3 gives 36.5%), TTF-1 (55.4%) and napsin A (52.7%) could not differentiate the two tumours.
  • p40 was positive in 2 of 36 mesotheliomas (5.6%, both in an extremely confined area) and in 94.7% of carcinomas. Its diagnostic accuracy was 94.6%.
  • Claudin-4 was positive in 2 of 36 mesotheliomas (5.6%) and in 92.1% of carcinomas. Its sensitivity was 94.4%, specificity 92.1% and diagnostic accuracy 93.2%.
  • MOC31 was positive in 12 of 36 mesotheliomas (33.3%) and in 89.5% of carcinomas. The authors did not recommend it as a carcinoma marker.
  • Among marker pairs used as positive markers for mesothelioma, requiring both calretinin and WT1 to be positive gave the highest diagnostic accuracy (86.5%). Counting a case as positive when either marker was positive gave 74.3% (Table 4).
  • Among pairs used as negative (carcinoma) markers, requiring both p40 and CEA to be negative gave the highest diagnostic accuracy (97.3%); accepting either as negative gave 93.2%. Requiring both CEA and claudin-4 to be negative gave 94.6% (Table 5).
• The authors' conclusion: The authors recommended WT1 and calretinin as positive markers, and CEA and claudin-4 as negative markers, for distinguishing solid epithelioid mesothelioma from poorly differentiated squamous cell carcinoma. They advised using claudin-4 rather than p40 as the carcinoma marker, and said new mesothelium-specific markers are needed.
• Limitations the authors state:
  • WT1 positivity in mesothelioma (72.2%) was lower than in an earlier study by Ordonez et al. The authors suggested differences in antibody source or staining system might explain this.
  • A small number of mesotheliomas stained for p40 and/or p63, mostly weakly. The authors said this must be kept in mind in practice.
  • Using p40 as a carcinoma marker could lead to misdiagnosing solid lung adenocarcinoma as mesothelioma, because p40 is rarely expressed in adenocarcinoma.

Topics

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

Medical terms in this study, explained in our Lexicon: Immunohistochemistry, Differential Diagnosis, Epithelioid, Mesothelioma, Squamous Cell Carcinoma, Calretinin, Podoplanin (D2-40), Carcinoembryonic Antigen (CEA).

Related studies

• 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)
• Use of Anti-Noxa Antibody for Differential Diagnosis between Epithelioid Mesothelioma and Reactive Mesothelial Hyperplasia — K. Kushitani, V.J. Amatya, et al. (2016)
• p40 is the best marker for diagnosing pulmonary squamous cell carcinoma: comparison with p63, cytokeratin 5/6, desmocollin-3, and sox2 — T. Tatsumori, K. Tsuta, et al. (2014)
• Application of immunohistochemistry in the diagnosis of epithelioid mesothelioma: a review and update — N.G. Ordóñez (2013)
• Diagnostic utility of immunohistochemistry in distinguishing between epithelioid pleural mesotheliomas and breast carcinomas: a comparative study — N.G. Ordóñez, A.A. Sahin (2014)
• Membranous HEG1 expression is a useful marker in the differential diagnosis of epithelioid and biphasic malignant mesothelioma versus carcinomas — K. Hiroshima, D. Wu, et al. (2021)

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