Salivary Duct Carcinoma

Abstract

A case of salivary duct carcinoma of the parotid gland is reported in a 58-year-old man who presented with an enlarged lymph node in the right upper neck and whose only risk factor for malignancy was a history of occupational radiation exposure. Fine needle aspiration biopsy yielded a carcinoma with cytologic features reminiscent of apocrine-type breast carcinoma. Immunohistochemical stains for keratin, androgen receptor, and gross cystic disease fluid protein-15 were all positive. Imaging studies identified an infiltrative mass in the deep lobe of the right parotid gland and multiple pathologically enlarged right cervical lymph nodes. The combination of the clinical presentation, cytologic features, and the results of immunostains was consistent with a diagnosis of salivary duct carcinoma. Total parotidectomy and modified radical neck dissection were subsequently performed and microscopic evaluation confirmed the diagnosis. Salivary duct carcinoma is a clinically aggressive carcinoma with pathological features that resemble high-grade ductal adenocarcinoma of the breast. Most tumors are positive for androgen receptor. Although uncommon, the histologic appearance of salivary duct carcinoma is distinctive. Awareness of this entity is important for accurate diagnosis. Appropriate adjunctive testing may inform clinical management in advanced cases.