[1244] Human Papillomavirus Status by In-Situ Hybridization and Correlation with p16 Immunohistochemistry in Adenoid Cystic Carcinoma of the Head and Neck

SM O'Connor, CA Moskaluk, MH Stoler, EB Stelow. University of Virginia Health System, Charlottesville, VA

Background: Although chronic alcohol and tobacco use are well-known risk factors for head and neck carcinoma, 15 to 20% of patients have no exposure to these substances. Reports indicate that human papillomavirus (HPV) is associated with head and neck squamous cell carcinomas (HNSCCs), particularly those involving the oropharynx and those with a basaloid phenotype. P16 expression and HPV status are not well described in other head and neck carcinomas, including those included in the differential diagnosis with basaloid SCCs. The purpose of this study is to determine status of p16 and HPV in adenoid cystic carcinomas (ACCs) of the head and neck.
Design: Tissue microarrays were constructed from 26 archival formalin-fixed, paraffin-embedded ACCs. Each tumor was represented by 3 cores. The Ventana HR HPV III probe set was used to perform automated ISH on the microarrays. IHC was performed using an antibody to p16INK4 (CINtec, MTM Laboratories). Antibody to p16 was determined to be immunoreactive if strong nuclear and cytoplasmic staining was present in >5% of cells and nonreactive if ≤5% stained.
Results: Of the 26 ACCs, 14 were immunoreactive with antibodies to p16 (54%), but none of these cases showed HPV by ISH. No p16 non-reactive cases demonstrated HPV. Of the 14 p16 immunoreactive tumors, 13 were cribriform, tubular, or mixed pattern (93%); only 1 of 14 was solid (7%). Six of the 12 p16 non-reactive tumors were mixed (50%); 4/12 (25%) were solid; 2 were tubular, but none were pure cribriform.
Conclusions: In contrast to the good correlation between p16 IHC and HPV ISH seen in HNSCCs, there is essentially no correlation between p16 immunoreactivity and presence of HPV in ACCs. Loss of p16 may be associated with a worse prognosis as it was more often associated with a solid growth pattern. Given the high rate of p16 immunoreactivity in ACCs, p16 cannot be used to distinguish ACC from basaloid squamous cell carcinoma. However, HPV in situ hybridization may be helpful.
Category: Head & Neck

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 157, Tuesday Afternoon

 

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