[361] Comparing HPV ISH and P16 in Assessing Metastatic Oropharyngeal Carcinoma

Nazneen Fatima, Cynthia Cohen, Momin T Siddiqui. Emory University, Atlanta, GA

Background: Background: The strong association of Oropharyngeal cancers (OPCs) with Human papilloma virus (HPV) infection, mainly HPV-16 and HPV-18, is now well recognized and well reported from various studies worldwide. HPV-positive tumors comprise a unique subset of head and neck squamous cell carcinomas (HNSCCs) that are different from HPV-negative tumors in respect to tumor differentiation, genetic changes, risk factors, risk stratification and prognosis. Detection of HPV status is now a standard practice in the pathological evaluation of HNSCCs. Strong correlations have been reported between diffuse nuclear and cytoplasmic p16 immunohistochemical staining (IHC) and HPV DNA detection by ISH. P16 IHC is used as a reasonable surrogate marker for high-risk HPV. Metastatic OPC may be the first clinical manifestation of the primary tumor and its evaluation may help in detecting the primary site. In this study we have compared the efficacy of HPV ISH and P16 IHC in the evaluation of metastatic OPCs.
Design: A total of 53 fine needle aspiration cell blocks (CB) from metastatic OPCs were evaluated with HPV ISH and P16 IHC. HPV ISH was interpreted as positive if a minimum of one tumor cell showed punctuate dot like nuclear positivity, P16 was interpreted as positive if 70% of tumor cells showed brown nuclear and cytoplasmic staining.10 CB from lung squamous cell carcinoma were taken as negative controls.
Results: Thirty four of 53 CB (64%) were positive for HPV ISH and 23 of 53 (43%) were positive for P16 IHC. 21 of 53 (39%) CB were positive for both HPV ISH and P16. The 10 CB from lung squamous cell carcinoma negative controls were all uniformly negative for HPV ISH and P16.

 HPV ISHP16Both
CB34/53 (64%)23/53 (43%)21/53 (39%)


Statistical analysis in CB

 SensitivitySpecificityPPVNPVAccuracy
HPV ISH64%100%100%34%69.8%
P1643%100%100%25%52%
PPV: Positive predictive value, NPV: Negative predictive value


Conclusions: In comparing HPV ISH with P16 in cell blocks, we have determined that HPV ISH plays a more important role in determining HPV status in comparison to P16, as noted by a higher sensitivity, NPV and Accuracy rate. P16 staining is easier to recognize and evaluate on tumor cells in contrast to punctuate dot like positivity seen in HPV ISH which may be very focal and requires careful evaluation at a higher magnification. A definite learning curve exists for pathologists in evaluating HPV ISH since the task may be laborious and time consuming. The combination of both HPV ISH and P16 in assessing for metastatic OPC may be helpful in determining the HPV status of these tumors.
Category: Cytopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 59, Monday Morning

 

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