BRCA Associated Protein-1 Immuno-Histochemical Stain in Diagnosis of Malignant Mesothelioma

Abstract

Objective: To differentiate malignant mesothelioma from benign mesothelial proliferations and other histological mimickers such as adenocarcinoma and squamous cell carcinoma, utilizing BRCA Associated protein1 (BAP1) immune-histochemical stain.

Study Design: Retrospective longitudinal study.

Place and Duration of Study: Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore Pakistan, from 2015 to 2020.

Methodology: We examined BAP1 IHC expression in 82 cases, including 56 malignant mesotheliomas, 12 Adenocarcinomas, and 14 Squamous cell carcinomas. Fifty-six malignant mesotheliomas included 49 epithelioid, 6 Biphasic and one sarcomatoid subtype. Loss of expression was established for cases showing complete loss of nuclear staining.

Results: Of 56 malignant mesotheliomas, 38(67.85%) showed loss of BAP1 expression, whereas 18(32.14%) showed retained expression. Of 12 adenocarcinoma cases, 10(83.33%) showed retained expression. Similarly, out of 14 squamous cell carcinomas, 12(85.71%) showed retained expression.

Conclusion: Loss of nuclear expression of BAP1 IHC serves as a valuable diagnostic ancillary tool in distinguishing malignant mesothelioma from its histological mimickers.
Keywords: BAP1, Immunohistochemistry, Malignant mesothelioma.