241 Coexistence of Immunochemical Features of Usual Type and Differentiated Type Vulvar Intraepithelial Neoplasia—A Rare Case Report. (11th January 2018)

• Record Type: Journal Article
• Authors: Xiong, Yiqin; Khan, Ashraf; Bai, Hongwei
• Is Part Of: American journal of clinical pathology. Volume 149(2018)Supplement 1
• Page Start: S102
• Page End: S103
• Publication Date: 2018-01-11
• Subjects: Diagnosis, Laboratory -- Periodicals; Pathology -- Periodicals; 616.07
• DOI: 10.1093/ajcp/aqx123.240
• Languages: English
• ISSNs: 0002-9173

Abstract

Abstract: Objectives: Current classification of squamous cell carcinoma precursors includes two distinct categories: HPV-dependent low-grade or high-grade squamous intraepithelial lesions (LGSIL, HGSIL) and HPV-independent TP53-associated differentiated type VIN (dVIN). Distinguishing between these two is important because the risk of progression to invasion can be rapid in dVIN. Methods: A 64-year-old woman presented with a right vulvar lesion for presurgical consultation in our institution. Her previous biopsy at another hospital was diagnosed as dVIN based on the morphology, patchy p16 and weak p53 staining. Right vulvar excision and immunochemical analyses were performed. Results: Sections show areas of irregular elongation and anastomoses of the rete ridges, basal and parabasal keratinocytic atypia with terminal differentiation but with areas of abnormal keratinization. The overlying hyperkeratosis and a background of lichen sclerosus are present. Immunostains for p53, p16, and Ki67 were performed, which showed an unequivocal evidence of mostly parabasal nuclear p53 positivity, with elevated Ki67-labeling index. The findings are highly suggestive of dVIN. However, a "block-type, " strong and diffuse nuclear and cytoplasmic p16 positivity is present on p16 immunostain in the lesional cells. Molecular tests for high-risk HPV were performed and showed negative results for a selected panel. Although the treatment for both entities is wide local excision, the unique staining results on p53 and p16 in this vulvar lesion posed a challenge in the diagnosis. Conclusion: This is a rare case showing both typical immunochemical features for two distinct entities in vulvar precancerous lesions. This suggests (1) diffuse and strong with a "block-type" positivity of p16 is probably not sufficient to rule out dVIN; or (2) there is a possibility of unusual high-risk HPV infection associated with TP53 mutation in this patient. These two events might not be mutually exclusive of tumorigenesis of vulvar intraepithelial neoplasia.