[710] Diagnostic Approach to Anal Condylomas Using p16, HPV L1 Capsid Protein and HPV Chromogenic In-Situ Hybridization

Deepa T Patil, Bin Yang. Cleveland Clinic, Cleveland, OH

Background: Most anal condylomas arise as a result of low-risk HPV infection and thus behave in an indolent manner. In comparison to cervical neoplasia, there is conflicting data whether documentation of HPV infection alone qualifies anal condylomas to be classified as dysplastic lesions. It is also unclear as to what percentage of condylomas harbor dysplasia. The current study was undertaken to systematically evaluate p16 and HPV L1 capsid protein expression and correlate these findings with HPV status. In addition, we also analyzed the utility of these markers in diagnosing dysplasia in a background of condyloma.
Design: A total of 43 anal condylomatous lesions were histologically reviewed and evaluated for nuclear HPV L1 staining, p16 staining (diffuse or patchy/focal), and low-risk (LR) and high-risk (HR) HPV status by chromogen in-situ hybridization. Dysplasia (low-grade or high-grade anal squamous intraepithelial neoplasia; LG-ASIN, HG-ASIN) was diagnosed only in the presence of HR-HPV or combined LR and HR-HPV reactivity.
Results: Of 43 lesions examined from 42 patients (27 men, 15 women), 29 (67%) were negative for dysplasia and 14 (32%) had coexisting squamous dysplasia, including 12 cases of LG-ASIN and 2 cases of HG-ASIN. Among 29 cases of condylomas without dysplasia, 24 (85%) harbored LR-HPV and none had HR-HPV infection. All 29 cases (100%) showed negative or patchy p16 immunostaining, while 19 cases (66%) expressed HPV L1 capsid protein. All 14 cases of condylomas with dysplasia had detectable HR-HPV either alone or with LR-HPV. p16 immunostaining showed focal/patchy staining pattern in condylomas with LG-ASIN and diffuse staining pattern in condylomas with HG-ASIN. HPV L1 expression was seen in all 12 cases of condyloma with LG-ASIN and one of two cases of condyloma with HG-ASIN.
Conclusions: Our study indicates that nearly a third of condylomas show dysplasia, supported by detectable HR-HPV and increased p16 immunoreactivity. Diffuse p16 staining pattern is a hallmark of malignant transformation from condyloma to HG-ASIN. In contrast, expression of HPV L1 capsid protein in condylomas with LG-ASIN suggests the episomal non-integrated stage of HPV infection in the low -grade anal squamous lesions.
Category: Gastrointestinal

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 104, Wednesday Morning

 

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