Salivary Gland Secretory Carcinoma With High-Grade Transformation, CDKN2A/B Loss, Distant Metastasis, and Lack of Sustained Response to Crizotinib
Background. Salivary gland secretory carcinoma is usually a low-grade neoplasm. However, high-grade transformation can occur and has important implications for clinical outcome. Methods. A patient presented with an enlarging buccal mass. Magnetic resonance imaging (MRI) showed a tumor with a biphasic appearance along the right parotid duct. Local excision and histopathologic examination confirmed the diagnosis of secretory carcinoma with high-grade transformation. ETV6-NTRK3 translocation and loss of CDKN2A/B were identified. Results. The patient subsequently presented with cough and dyspnea and was found to have pleural metastases. Carboplatin and paclitaxel exacerbated the symptoms. Crizotinib resulted in initial symptomatic and radiographic improvement; however, the patient soon succumbed to progressive intrathoracic disease. Conclusions. High-grade salivary gland secretory carcinoma can have a biphasic appearance on MRI. Diagnosis is confirmed by the histologic appearance and associated ETV6-NTRK3 fusion. Additional molecular genetic events leading to transformation are unknown; however, loss of CDKN2A/B may have contributed. Treatment with multimodal chemotherapy was of limited benefit.