[1166] A Comparative Analysis of LEF-1 in Odontogenic and Salivary Tumors.

Elizabeth A Bilodeau, Marie Acquafondata, Leon Barnes, Raja R Seethala. University of Pittsburgh, PA

Background: Odontogenic tumors may occasionally prove difficult to distinguish from salivary gland tumors in the oral cavity, particularly those with basaloid morphology. We evaluate the potential utility of LEF-1, a nuclear transcription factor involved in tooth and hair follicle development, in distinguishing between these tumors.
Design: Immunohistochemical staining for LEF-1 (sc-8591, 1:200 dilution; Santa Cruz Biotechnology, Santa Cruz, CA, USA) was performed on paraffin sections from 23 basaloid salivary gland carcinomas (16 basal cell adenocarcinomas (BCAC), 7 adenoid cystic carcinomas (ACC) ), and 25 odontogenic tumors (13 ameloblastomas, 5 calcifying cystic odontogenic tumors, 3 adenomatoid odontogenic tumors, 2 calcifying epithelial odontogenic tumors, 1 ameloblastic carcinoma, and 1 squamous odontogenic tumor). Hair follicle bulb was used as a positive control.
Nuclear staining intensity (grades 0-3) and percentage of positive cells were recorded. A value between 1 and 4 was assigned for the percentage of positive cells (1 for 0-25%, 2 for 26-50%, 3 for 51-75% and 4 for 76 to 100%). The product of intensity and positive cells was calculated for a composite score (range: 0-12). Positivity was defined as at least 2+ intensity in >50% of tumor cells which required a composite score of >6.
Results: LEF-1 was positive in 80% (4/5) calcifying cystic odontogenic tumors, 15% (2/13) of ameloblastomas, and 33% (1/3) of adenomatoid odontogenic tumors. The calcifying epithelial odontogenic tumors, ameloblastic carcinoma, and squamous odontogenic tumor were negative.
Strong and diffuse LEF-1 expression was seen in 69% (11/16) of BCACs, which was significantly more frequent that in ACCs, which were only positive in 14% (1/7) of cases (Fisher exact, 2-tail p = 0.027). No LEF-1 staining was seen in any components of normal salivary gland parenchyma. LEF-1 expression was greatest in the peripheral basal layer of BCACs. 100% (4/4) of tubulotrabecular and (1/1) cribriform patterned BCACs stained for LEF-1; whereas, 67% (4/6) of solid and 40% (2/5) of membranous patterned expressed LEF-1.
Conclusions: We document for the first time the presence of LEF-1 expression in select basaloid salivary gland carcinomas. This finding combined with the low frequency of immunoexpression in most of the tested odontogenic tumors argues against its utility in distinguishing salivary gland tumors from odontogenic tumors. However, it appears that BCACs frequently express LEF-1 suggesting that these are truly 'dermal analogue tumors' phenotypically. This strong expression may have utility in distinguishing these tumors from ACC.
Category: Head & Neck

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 145, Wednesday Morning


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