[361] Comparing Automated with Manual HPV ISH, and P16 Immunohistochemistry in Assessing Metastatic Oropharyngeal Carcinoma (OPC)

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

Background: HPV-positive tumors are 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 and prognosis. Detection of HPV status is now a standard practice in the pathologic evaluation of HNSCCs. Detection of HPV in metastatic cancer in neck lymph nodes may also be used to localize the primary within oropharynx, with a high degree of certainty. Determining the integration status of HPV by in situ hybridization (ISH) is cost effective and routinely utilized in clinical practice. Strong correlations have been reported between diffuse nuclear and cytoplasmic p16 immunohistochemical staining (IHC) and HPV DNA detection by ISH. In this study, we compared the efficacy of automated HPV ISH utilizing the Enzo probe with manual HPV ISH utilizing the Dako probe, and P16 IHC in the evaluation of metastatic OPCs.
Design: Forty one fine needle aspiration (FNA) cell blocks (CB) from metastatic OPCs were evaluated with automated HPV ISH utilizing the Enzo probe, the manual HPV ISH with the Dako probe, and P16 IHC. HPV ISH was interpreted as positive if a minimum of one tumor cell showed punctate dot like nuclear positivity. P16 was interpreted as positive if 70% of tumor cells showed brown nuclear and cytoplasmic staining. Ten CB from lung squamous cell carcinoma were studied as negative controls.
Results: Thirty of 41 CB (73%) were positive for automated HPV ISH; 25 of 41 CB (60%) with manual HPV ISH. Eighteen of 41 (43%) CB were positive for P16 IHC. The 10 CB from lung squamous cell carcinoma negative controls were all uniformly negative for HPV ISH by both techniques, and P16.

Summary of ISH and IHC results
 HPV ISH (automated)HPV ISH ( manual)IHC P16
CB30/41 (73%)25/41 (60%)18/41 (43%)




Statistical analysis in CB
 SensitivitySpecificityPPVNPVAccuracy
HPV ISH (automated)73%100%100%47%78%
HPV ISH (manual)60%100%100%38%68%
P16 IHC43%100%100%30%54%
Abbreviations: PPV, positive predictive value; NPV, negative predictive value


Conclusions: In comparing automated HPV ISH utilizing Enzo probe with manual HPV ISH utilizing the Dako probe, and P16 IHC, we have determined that automated HPV ISH plays a more significant role in determining the HPV status in CB as compared to the other two techniques. P16 staining is easier to recognize and evaluate on tumor cells in contrast to punctate dot like positivity seen in HPV ISH which may be very focal and requires careful evaluation at a higher magnification.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 69, Tuesday Afternoon

 

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