Head and Neck Pathol (2009) 3:69–77 DOI 10.1007/s12105-009-0102-9 P R O C E E D I N G S O F T H E 2 0 0 9 N O R T H A M E R I C A N S O C I E T Y O F H E A D A N D N E C K P A T H O L O G Y C O M P A N I O N M E E T I N G ( B O S T O N , M A ) An Update on Grading of Salivary Gland Carcinomas Raja R. Seethala Received: 19 December 2008 / Accepted: 18 January 2009 / Published online: 25 February 2009 Humana 2009 Abstract Histologic grade is a signiﬁcant predictor of outcome in salivary gland carcinomas. However, the sheer variety of tumor type and the rarity of these tumors pose challenges to devising highly predictive grading schemes. As our knowledge base has evolved, it is clear that carci- noma ex pleomorphic adenoma is not automatically a high grade tumor as is traditionally suggested. These tumors should be further qualiﬁed as to type/grade of carcinoma and extent, since intracapsular and minimally invasive carcinomas ex pleomorphic adenoma behave favorably. The two carcinoma types for which grading schemes are common include adenoid cystic carcinoma and mucoepi- dermoid carcinoma. Adenoid cystic carcinomas are graded based solely on pattern with solid components portending a worse prognosis. Occasionally, adenoid cystic carcinomas may undergo transformation to pleomorphic high grade carcinomas. This feature confers a high propensity for lymph node metastasis and should thus be reported to alert the clinical team. Mucoepidermoid carcinomas are graded in a three tier fashion based on a constellation of features including cystic component, border, mitoses, anaplasia, and perineural invasion among others. All grading schemes are somewhat cumbersome, intimidating and occasionally ambiguous, but evidence suggests that using a scheme consistently shows greater reproducibility than using an intuitive approach. The intermediate grade category dem- onstrates the most variability between grading systems and thus the most controversy in management. In the AFIP system intermediate grade tumors cluster with high grade R. R. Seethala (&) Department of Pathology and Laboratory Medicine, University of Pittsburgh Medical Center, A616.3 PUH, 200 Lothrop St, Pittsburgh, PA 15213, USA e-mail: seethalarr@upmc.edu tumors, while in the Brandwein system, they cluster with low grade tumors. Keywords Grading Salivary carcinoma Mucoepidermoid carcinoma Adenoid cystic carcinoma High grade transformation Carcinoma ex pleomorphic adenoma Introduction Salivary gland carcinomas comprise only 3–5% of all head and neck malignancies, yet they are the most diverse with at least 24 different types recognized by the World Health Organization (WHO) [1]. This diversity combined with the rarity of many of the tumor types and the unpredictability in long-term outcome impose a signiﬁcant challenge on the management of salivary gland malignancies overall [2]. For prognosis and treatment, despite these aforementioned factors, it is critical to resolve these tumors, using both clinical and pathologic parameters, into therapeutically meaningful categories (Table 1) [3]. A review of numerous retrospective studies [4] indicates that histologic tumor grade ranks highly among the most important predictors of outcome for salivary gland carci- nomas. High grade salivary carcinomas have a 5 year survival of roughly 40% while low and intermediate grade tumors have a 5 year survival of 85–90% [2, 4]. In sizeable series, histologic grade is an independent predictor of outcome in multivariate analysis, but it also tends to cor- relate with other adverse prognosticators such as size and nodal status. However, the current approach to grading of salivary gland tumors is subject to many deﬁciencies and challenges that on a case by case basis may not always accurately predict outcome. Here I review current