MR imaging features of mammary analogue secretory carcinoma and acinic cell carcinoma of the salivary gland: a preliminary report.

Objectives: To report MR imaging features of mammary analogue secretory carcinoma (MASC) and acinic cell carcinoma (AciCC) of the salivary gland based on the latest version of the World Health Organization (WHO) 2017 classification of head and neck tumours. Methods: MR images in 4 patients with MASC and 4 with AciCC were reviewed for margin characteristics, the presence of pathological cervical nodes, the presence of a cystic component and interface between cystic and solid component, signal intensity of the cystic components on T-1 weighted images, and signal intensity of the solid component on T-1 and T-2 weighted images. Results: All the MASCs and AciCCs had well-defined boundaries, and 1 AciCC had pathological nodes. All 4 MASCs presented as predominantly cystic tumours with papillary projection of the solid component. All 4 AciCCs presented as solid tumours. The signal intensity of the cystic components on T-1 weighted images was entirely hyperintense in 2, and partly hyperintense demonstrating fluid-fluid level in 2. In all the MASCs, the signal intensity of the solid components on T-1 weighted images was intermediate. In the AciCCs, the signal intensity of the solid components on T-1 weighted images was high in 2 tumours and intermediate in 2. The signal intensity of the solid components on T-2 weighted images varied from low to high in both MSACs and AciCCs. Conclusions: All 4 MASCs had a large cystic component, including areas of high signal intensity on T-1 weighted images. The solid component appeared as a papillary projection into the cystic component. All 4 AciCCs presented as solid tumours, 2 of which showed high signal intensity on T-1 weighted images.