[1309] Prognostic Features and Grading in Mucoepidermoid Carcinoma of Major Salivary Glands

Nora Katabi, Ronald Ghossein, Safina Ali, Snjezana Dogan, David Klimstra, Ian Ganly. MSKCC, New York

Background: Mucoepidermoid carcinoma (MEC) has widely diverse biologic behavior. Grading MEC is important prognostically and therapeutically; however, there is no uniformly accepted grading system. The aim of this study is to assess adverse prognostic features of MEC in relation to outcome and to compare different grading systems.
Design: 72 cases of MEC were subjected to a detailed histopathologic analysis. Four grading systems were used: AFIP, Brandwein, Healy, and our own (personal system mainly based on the architecture and cytology of the tumor). 5 yr estimates of survival were performed.
Results: 20 of 72 cases were misdiagnosed as MEC; 4 as low grade (LG) and 18 as high grade (HG). The 18 HG were reclassified as follows: 2 salivary duct carcinoma, 11 squamous cell carcinoma, and 3 HG carcinoma unclassifiable. Among the 52 MEC, median patient age was 50 with female predilection of 1:2. Tumors were predominantly located in the parotid (50 parotid/2 submandibular). Mean tumor size was 1.77 cm. Lymphoid stroma was found in 83% of tumors. Perineural invasion, vascular invasion, and lymph node metastasis were identified in 19%, 6%, and 9%, respectively. Only 1 patient developed distant metastasis to the lung. Median follow-up was 50 months (1-237). 5 yr estimates of disease specific survival (DSS) and recurrence free survival (RFS) were 95% and 89%, respectively. Mitosis (≥4/10 HPFs), necrosis, pleomorphism, focal keratinization, desmoplasia, and lymph node metastasis were associated with adverse DSS and RFS (P < .002). Vascular invasion, tumor size > 2cm, and infiltrative borders were associated with adverse RFS (P < .002). In all 4 grading systems, LG and intermediate grade (IG) had similar DSS and RFS survival but much better outcome than HG (P<0.007). All patients with a low mitotic rate and no necrosis did not recur except for 1 patient with a positive margin. All patients with tumors showing a high mitotic rate and necrosis died or recurred. Lack of consensus among grading systems was found in 23 out of 52 cases. Among the 23 cases, 3 LG tumors and 1 IG using AFIP criteria were upgraded to HG using Brandwein. None of these 4 patients died or recurred.
Conclusions: 1) HG MEC is very rare and the majority of previously diagnosed HG MEC cases are misclassified. 2) There is no difference in outcome between LG and IG using any grading system. 3) Consideration should be given to stratify MEC into two grade categories based on relatively objective criteria such as mitosis sand necrosis.
Category: Head & Neck

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 154, Tuesday Afternoon


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