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Figure 1. 78-year-old woman with basal cell adenoma of the right parotid gland. (a) Post-contrast CT image in the early phase (at 30 s) shows a multinodular tumour with strong contrast enhancement. (b) Post-contrast CT image in the delayed phase (at 25 min) shows less enhancement of the tumour than in the early phase. (c) CT attenuation-time (HU) curve shows strong enhancement in the early phase and gradually reduced enhancement at later phases. (d) Non-contrast axial T1 weighted MRI (500/14, repetition time/echo time (TR/TE)) shows isointense mass. The region of mild hyperintensity at the right lateral aspect is consistent with haemorrhage. (e) Axial T2 weighted MRI (3800/90, TR/TE) shows a hyperintense mass lesion surrounded by a hypointense capsule. Note the higher intensity in the right lateral aspect of the lesion. (f) Histological section of the parotid mass shows material resembling basal membrane surrounding an island of tumour cells. Note the trabecular pattern of tumour cells, some of which have formed palisades, with narrow cytoplasm and hyperchromatic nuclei (haematoxylin and eosin x 100).
