Carcinoma ex pleomorphic adenoma: case report and options for systemic therapy

Abstract

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.

Keywords: Carcinoma ex pleomorphic adenoma; chemotherapy; cisplatin; cyclophosphamide; doxorubicin.

FIGURE 1

(A) Initial pathology, demonstrating a pleomorphic adenoma with mixed epithelial and myoepithelial elements, together with chondromyxoid stroma. (B) Biopsy taken at the time of malignant recurrence demonstrates a high-grade spindle-cell neoplasm, with marked cytologic atypia and brisk mitotic activity.

FIGURE 2

Axial computed tomography images obtained 6 months apart show the left parotid mass (arrow) (A) before and (B) after treatment with 6 cycles of cyclophosphamide–doxorubicin–cisplatin.