[488] Basal Cell Carcinomas of the Vulva Are Unrelated to High-Risk Human Papillomavirus

Hillary Elwood, Jinah Kim, Brigitte M Ronnett, Janis Taube. The Johns Hopkins Hospital, Baltimore, MD; Stanford University Hospital, Stanford, CA

Background: Basal cell carcinoma (BCC) of the vulva is rare and may be confused with the much more commonly encountered high-risk human papillomavirus (HPV)-related basaloid squamous cell carcinoma (SCC) of the vulva. Basaloid SCCs are characterized by a diffuse p16 expression pattern which serves as a surrogate marker for high-risk HPV in these tumors. The HPV status of BCCs is not well-established: p16 expression studies are limited and analysis by HPV in situ hybridization has not been previously reported. This study assesses the utility of p16 expression patterns and high-risk HPV detection in a series of vulvar BCCs for distinction of these tumors.
Design: Twelve cases of vulvar BCC identified in the surgical pathology archives from 1996 to 2010 were analyzed. P16 expression was assessed by immunohistochemical analysis and HPV status was assessed by in situ hybridization with a wide-spectrum probe for high-risk HPV types. P16 staining patterns were scored as either diffusely positive (>90% of tumor cells positive) or as patchy positive/negative when a lesser extent of staining or absence of staining was encountered.
Results: The average age of the patients was 80.3 years (range 54-95). All tumors (12/12) demonstrated patchy p16 positivity, with <50% of tumor cells expressing p16 in all cases. None demonstrated the diffuse p16 expression characteristic of high-risk HPV-associated lesions. No high-risk HPV was detected by in situ hybridization (0/12).
Conclusions: The lack of diffuse p16 expression and failure to detect high-risk HPV by in situ hybridization in vulvar BCCs indicate that these tumors are unrelated to high-risk HPV. These ancillary techniques, particularly p16 immunohistochemical analysis which is readily performed in most laboratories, are useful for distinguishing vulvar BCCs from basaloid forms of high-risk HPV-related vulvar SCC. Distinction of these tumors is important due to differences in extent of surgical treatment for these entities.
Category: Dermatopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 127, Wednesday Afternoon

 

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