BAP1-loss in the salivary duct carcinoma component of an intracapsular carcinoma ex pleomorphic adenoma of the parotid gland

Abstract

Abstract Background BRCA1 associated protein 1 (BAP1) is a tumor suppressor gene that is altered in a variety of neoplasms as well as in BAP1 tumor predisposition syndrome. BAP1 alterations are associated with aggressive behavior in some malignancies and may have treatment implications in the future. We present the first documented case of a BAP1 alteration in the salivary duct carcinoma (SDC) component of an intracapsular carcinoma ex pleomorphic adenoma (CXPA). Methods A woman of approximately 55 years of age presented with a deep parotid lobe mass, which was resected and found to be CXPA. BAP1 immunohistochemistry and next generation sequencing were performed to further characterize the neoplasm. Results The neoplasm showed loss of BAP1 protein expression in the SDC component but retention in the residual pleomorphic adenoma (PA) and at least partial retention in the epithelial-myoepithelial carcinoma (EMC). Next generation sequencing confirmed a BAP1 loss of function alteration. Conclusion The presence of a BAP1 alteration in the SDC component of a CXPA may have prognostic and treatment implications, and additional studies are needed to investigate the relevancy of BAP1 alterations in salivary gland malignancies.