Carcinoma Ex Pleomorphic Adenoma: Case Report and Options for Systemic Therapy

The most common benign salivary tumour is a pleomorphic adenoma. Transformation to malignancy, carcinoma ex pleomorphic adenoma (CXPA), occurs in 6% of cases. Management focuses on surgical resection and radiotherapy; however, rare cases require systemic management. We present the case of a 60-year-old woman with a CXPA of the left parotid gland who required systemic therapy for locally recurrent disease. Treatment options were guided by the literature concerning malignant salivary gland tumour and by whole-genome and transcriptome sequencing of the tumour. The patient received multiple systemic agents during the course of her disease, with cyclophosphamide–doxorubicin–cisplatin providing the best control (partial response). Genomeand transcriptome-directed therapy, including sorafenib and vismodegib, were utilized with limited clinical benefit. Malignant transformation in CXPA is a complex process, and therapy directed at a single tumour pathway might not be sufficient to control disease.