Comparison of histological grading methods in mucoepidermoid carcinoma of minor salivary glands

Context: Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy and its grading is greatly consequential in the management and prognosis of patients with the disease. Aims: To compare histologic grading systems in MEC of minor salivary glands. Settings and Design: Two qualitative (modified Healy and Memorial Sloan-Kettering Cancer Center [MSKCC] methods) and two quantitative (Armed Forces Institute of Pathology [AFIP] and Brandwein methods) were evaluated. Subjects and Methods: Diagnostics slides of 19 patients including one recurrent case were evaluated using the four grading systems. Statistical Analysis Used: Percentages and proportions were used. Results: Agreement across all grading system was found to be very low (32%) while there was a better agreement between AFIP and MSKCC methods (84%) between modified Healy and Brandwein (58%). The method that gave the poorest agreement with all the others was the Brandwein grading. In general, the AFIP and MSKCC methods tended to grade the tumors lower while the Brandwein and modified Healy methods seemed to grade them higher. Conclusions: Most MEC of minor salivary glands appear to be low-grade tumors. It is conceivable that some grading methods (Brandwein and modified Healy) may lead to an unnecessary escalation of management methods in these tumors. The MSKCC method may have emphasized some parameters which may not have much importance in minor salivary gland MEC. The AFIP method appears to be the most appropriate to use for the grading of minor salivary gland MEC. Further studies are required to confirm or disprove this finding