ERBB2 and salivary duct carcinoma: Overexpression of HER2 has been reported in salivary gland carcinomas of excretory cell origin, including salivary duct and squamous cell carcinomas, but not in those of intercalated cell origin, including adenoid cystic, acinic cell, and adenocarcinomas, and it is associated with poor clinical prognosis in patients with salivary duct carcinoma [8].