Importance of Magnetic Resonance in the Diagnosis of Pleomorphic Parotid Adenoma: Clinical Case Series

Introduction: Parotid tumours represent about 3% of head and neck neoplasms, of which 80% are benign. The most common being the Pleomorphic Adenoma (PA). Objective: To analyse the morphological characteristics of the PA by Magnetic Resonance (MRI scan) and its behaviour in advanced diffusion (ADC - Apparent Diffusion Coefficient- value) and perfusion sequences. Materials and methods: Descriptive and inter-observer study of patients with a suspected PA diagnosis in an MRI scan and subsequent histological confirmation. All studies were carried out with the same MRI. The MRI protocol included enhanced sequences in T1 (T1W), T2 (T2W) diffusion study (DWI) and enhanced sequences in T1 with fat saturation (T1W FS) after injecting the contrast. Results: 39 of the 43 cases with suspected PA were confirmed (90.67%). They were morphologically well defined homogeneous tumours, with an average value of high ADC (1.85 x 10-3 mm2/s) and a type A perfusion curve (associated to benignity). The inter-observer concordance was 100%. Conclusions: PAs show typical morphological characteristics in an MRI scan. In case of diagnostic doubt, the diffusion and perfusion sequences help establish a definite diagnosis.