74 • • • It may be reasonable to indicate in a comment that a solid component [30% correlates with aggressive behavior. If evidence of high grade transformation is present, this should be reported and quantitated. A comment regarding the unusually high propensity for lymph node involvement is recommended. Mucoepidermoid Carcinoma Mucoepidermoid carcinoma is the most common salivary gland malignancy and is histologically comprised of a mixture of mucus cells, intermediate cells and squamoid or epidermoid cells. This tumor may also demonstrate clear cell, oncocytic or columnar cells. There is arguably no other salivary gland tumor in which grading is as important to prognosis and therapy. The reported overall 5 year sur- vival for MEC ranges from 92 to 100% for low grade Head and Neck Pathol (2009) 3:69–77 tumors, 62–92% for intermediate grade tumors, and 0–43% for high grade tumors [16]. A few recent studies have also highlighted the value of grade in the management of patients [17, 18]. Low grade tumors generally require only surgical treatment, while high grade tumors require adju- vant radiation and neck dissection. The controversy arises in the management of intermediate grade mucoepidermoid carcinoma, and perhaps the root of this controversy lies within the grading system employed. Even when described initially by Stewart et al. [19] in 1945, two types of mucoepidermoid carcinoma were doc- umented, a ‘benign’ and ‘malignant’ version which equate today to low and high grade respectively. Shortly thereaf- ter, the potential need for an intermediate category was recognized [20]. Today, mucoepidermoid are carcinoma graded by most using three tiers: low, intermediate and high grade. The three most popular grading systems are: the AFIP grading system [21], modiﬁed Healey sys- tem [22], and the Brandwein [23] system (Table 5). All categories assess a similar set of parameters, both AFIP [21] Point based Intracystic component \20% = 2pts Neural invasion present = 2pts Necrosis present = 3pts Brandwein [23] Point based Intracystic component \25% = 2pts Tumor invades in small nests and islands = 2pts Pronounced nuclear atypia = 2pts Table 5 Comparison of Grading Systems for Mucoepidermoid Carcinoma Modiﬁed Healey [22] Qualitative Low grade Macrocysts, microcysts, transition with excretory ducts Differentiated Mucin producing Epidermoid Cells, often in a 1:1 ration; minimal to moderate intermediate cell population Daughter cyst proliferation from large cysts Minimal to absent pleomorphism, rare mitoses Broad-front, often circumscribed invasion Pools of extravasated mucin with stromal reaction Intermediate grade No macrocysts, few microcysts, solid nests of cells Large duct not conspicuous Slight to moderate pleomorphism, few mitoses, prominent nuclei and nucleoli Invasive quality, usually well diﬁned and uncircumscribed Chronic inﬂammation at periphery, ﬁbrosis separates nests of cells and groups of nests High grade Perineural spread = 3pts No macrocysts, predominantly solid but may be nearly all glandular Necrosis = 3pts Cell constituents range from poorly differentiated to recognizable epidermoid and intermediate to ductal type adenocarcinoma Considerable pleomorphism, easily found mitoses Unquestionable soft tissue, perineural and intravascular invasion Chronic inﬂammation less prominent, desmoplasia of stroma may outline invasive Low grade = 0–4 pts clusters Intermediate grade = 5–6 pts High grade = 7–14 pts High grade = 4 or more pts Low grade = 0 pts Intermediate grade = 2–3 pts Mitosis (4 or more per Lymphatic and/or vascular 10 HPF) = 3pts invasion = 3pts Anaplasia = 4pts Bony invasion = 3pts [4mitoses per 10 HPF = 3pts