Salivary duct carcinoma of the parotid gland: clinical and MR features in six patients.

This study reports the clinical and MR features of salivary duct carcinoma (SDC) of the parotid gland, which is a rare and highly malignant tumour. We assessed retrospectively the clinical and MR features of six patients with histologically proven SDC of the parotid gland. The five men and one woman, ranging in age from 65-71 years (mean, 67 years), had undergone MRI before surgery. All patients presented with parotid masses and four patients had facial paralysis. Two had been aware of the parotid mass for more than 10 years. On MRI, all of the tumours had an ill-defined margin along either the entire circumference or part of the circumference. Four tumours showed infiltration into the subcutaneous or parapharyngeal space. Two tumours showed a wholly solid internal content, and four tumours had varying proportions of cystic content. The signal intensity of the solid portion was low to intermediate on both T(1) weighted and T(2) weighted images. Three patients showed multiple cervical lymph node swellings. Although SDC can show non-specific MRI findings, the combined findings (e.g. low-to-intermediate signal intensities on T(2) weighted images, ill-defined boundaries, infiltration into the surrounding fat space, facial nerve paralysis and associated cervical lymphoadenopathy, seem to suggest a high-grade malignancy.