Low-grade mucoepidermoid carcinoma with biologically aggressive behaviour

Abstract

<h3>Background</h3> Mucoepidermoid carcinomas are common tumours of the minor salivary glands and have diverse clinical outcomes. The most important histological parameter for predicting tumour behaviour is the tumour grade. <h3>Methods and Results</h3> We report a case of an 87-year-old male with right cheek swelling. The lesion was excised and tissue sections from paraffin blocks were stained with H&E. Histological examination revealed a mucoepidermoid carcinoma arising in the buccal mucosa, with direct bone invasion and metastatic tumour in one Level 1 lymph node. Using the Armed Forces Institute of Pathology (AFIP)^1,2 grading system, the tumour was classified as low grade, but demonstrated biologically high grade behaviour. <h3>Discussion</h3> Mucoepidermoid carcinomas are currently graded into low, intermediate and high grades using a weighted system by Auclair and Goode from the AFIP.^1,2 An alternate method of grading has been proposed by Brandwein³ which takes into consideration three features in addition to AFIP criteria including (i) lymphovascular invasion, (ii) bone invasion and (iii) pattern of tumour infiltration. This new system upgraded our tumour from low to high grade. This case illustrates some discordance between tumour grade and behaviour as defined by the AFIP system and demonstrates improved correlation between tumour grade and behaviour using the modified Brandwein system.