Metastases to the parotid nodes: CT and MR imaging findings

To present and characterize CT and MR imaging findings of metastases to the parotid nodes. CT (n = 10) and MR (n = 11) images from 14 patients with metastases to the parotid nodes were reviewed. The primary tumour sites were the ocular adnexa in five patients, facial skin in four patients, upper aerodigestive tract in four patients and thyroid gland in one patient. CT and MR images were evaluated with emphasis on the size and number of parotid tumours, their location in the parotid gland, the presence of associated clinically pathological cervical nodes or previous history of cervical node metastasis, margin characteristics and the presence of central necrosis. A total of 18 tumours were identified in 14 patients, with an average maximal cross-sectional diameter of 19 mm (7-44 mm). 12 patients had a single parotid tumour and 2 patients had unilateral multiple tumours; 12 tumours in 10 patients were located in the parotid tail, 6 tumours in 4 patients were located in the superficial lobe and no tumour was noted in the deep lobe. In the superficial lobe, four of six tumours were located in the pretragal area. Three of nine patients whose primary sites were the ocular adnexa or skin had associated clinically pathological cervical nodes. None of these patients had a previous history of cervical node metastasis. All five patients with other primary sites had associated pathological cervical nodes or a history of such. 11 tumours had well-defined margins and 7 tumours had ill-defined margins. Post-contrast images showed central necrosis in 2 of 11 tumours. Metastases to the parotid nodes tend to present as solitary parotid masses with two preferential sites.