Coexisting high-grade vulvar intraepithelial neoplasia (VIN) and condyloma acuminatum: independent lesions due to different HPV types occurring in immunocompromised patients.

The majority of vulvar intraepithelial neoplasia (VIN) is high-grade and is related to high-risk human papillomavirus (HRHPV) (most commonly HPV 16). It is considered to be the precursor of HRHPV-related vulvar squamous cell carcinoma. Vulvar condyloma acuminatum is low-risk HPV (LRHPV)-related (most commonly types 6 and 11) and has virtually no risk of neoplastic progression. While infection with multiple LRHPV and HRHPV types has been reported for cervical squamous intraepithelial lesions, coexisting vulvar condyloma and adjacent high-grade VIN have not been well characterized. Eleven cases of concurrent condyloma acuminatum and adjacent flat high-grade VIN and 3 cases of high-grade VIN with prominent condylomatous architecture were analyzed using immunohistochemical analysis of p16 expression, in situ hybridization (ISH) for HPV detection [HPV 6/11, HPV 16, HPV 18, and HPV wide spectrum (types 6, 11, 16, 18, 31, 33, 35, 45, 51, 52) probes], and HPV typing by a polymerase chain reaction (PCR)-based method (in select cases). All patients had underlying immunosuppressive conditions (human immunodeficiency virus infection or posttransplant therapy). Among the 11 cases of concurrent high-grade VIN and condyloma, the lesions were directly adjacent to one another in 5 cases (with 2 of these demonstrating an intimate admixture of lesions), and in 6 cases the lesions were found in separate tissue sections from the same specimen. Diffuse/strong p16 expression was seen in all high-grade VIN lesions, whereas patchy/weak staining was found in all condylomata. All condylomata contained HPV 6 or 11 as detected by ISH. HRHPV was detected in all of the accompanying high-grade VIN lesions. Ten contained HPV 16 (9 by ISH, 1 by PCR), with the remaining case containing multiple HPV types by PCR. All condylomatous high-grade VIN lesions demonstrated diffuse/strong p16 expression and had evidence of HRHPV (1 with HPV 16 by ISH, 1 with HPV 18 by ISH, and 1 with multiple HPV types by PCR), with no detection of HPV 6 or 11 by ISH. The restriction of LRHPV to condylomatous components and HRHPV to high-grade VIN components of adjacent lesions suggests these are independent lesions caused by different HPV types. Diffuse p16 expression can highlight small foci of high-grade VIN, which may be overlooked in more abundant condylomatous tissue from immunosuppressed patients. The presence of only HRHPV in those VIN lesions with high-grade cytologic features but prominent condylomatous architecture supports their classification as forms of pure high-grade VIN and distinguishes them from condyloma acuminatum.