[1286] Adenoid Cystic Carcinoma of Salivary Glands: Clinicopathologic Study with Emphasis on Myb Protein Expression

Nora Katabi, Allen Ho, Alan Ho, Ian Ganly, Ronald Ghossein. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Adenoid cystic carcinoma (ACC) is the second most common primary salivary gland malignancy which shows ductal and myoepithelial differentiation and different growth patterns. Recently, a t(6;9) translocation resulting in the MYB-NFIB fusion gene has been reported in ACC. In addition, overexpression of Myb protein has been demonstrated by IHC including both MYB-NFIB translocation positive and negative tumors. The aim of this study to assess prognostic factors in ACC with emphasis on Myb expression.
Design: 34 cases of ACC were retrieved from the pathology file. Myb immunostain was performed on 31 cases with <5% nuclear staining considered as negative. The cases were subjected to a detailed histopathologic analysis.
Results: Median patient age was 53.5 (24-79) with female predilection (20F/14M). Tumors were located in minor (21,62%) and major (13,38%) salivary glands. Mean size of tumor was 2.9 cm. The majority of tumor showed increased mitoses (56% with ≥3 mitosis/10HPFs), apoptosis (85%), and open chromatin pattern (60%). Tumor necrosis was identified in 6 cases (17%). The predominant growth pattern was cribriform in 70% of cases and solid in 8%. Peirneural invasion (PNI), vascular invasion and positive margins were noted in 79%, 0.8% and 75%, respectively. Median FU was 27 months. Two patients developed local recurrences, four had distant metastases, and four had LN metastases. None of the patients who had tumors with mitoses ≤ 3/10 HPFs developed distant metastases, while 4/18 (22%) patients with tumors showing >3 mitoses/10 HPFs developed distant metastases. Solid growth pattern did not correlate with recurrence. Myb stain was positive in 19/31 (61%) ACC. Myb staining was categorized as follows: 0 (39%), 5-50% (16%), and ≥50% (45%). Myb expression did not significantly correlate with the following: recurrences, distant or LN metastases, solid growth pattern, tumor necrosis, or PNI. However, MYB correlated with increased mitotic rate (>3/10 HPFs) (P<0.03).
Conclusions: Myb expression was found in 61% cases of ACC. MYB staining correlated with increased mitotic rate (>3/10 HPFs) (P<0.03). None of the patients who had tumors with mitoses ≤ 3/10 HPFs developed distant metastases which is suggestive that mitotic rate might be useful to grade ACC. Additional cases of ACC will be studied to further investigate the results.
Category: Head & Neck

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 153, Tuesday Morning


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