The pathology of superficially invasive, thin vulvar squamous cell carcinoma

Thirty-six cases of vulvar squamous cell carcinoma 5 mm or less in thickness were studied, and potential predictors of lymph node metastases were evaluated. Tumor thickness and depth of stromal invasion were measured. Inguinal lymph node metastases were present in six (17%) cases, all of which had primary neoplasms more than 3 mm thick. The most superficial lesion to have lymph node metastasis was 3.2 mm thick and had 1.6 mm of stromal invasion. Nonetheless, depth of stromal invasion of less than 3 mm was associated with statistically fewer lymph node metastases (7%) than that of neoplasms with 3 mm or more of stromal invasion (50%). Although lymphatic or blood capillary invasion was present in four (11%) cases, this feature had no statistically significant association with lymph node metastasis. There was no relationship between clinical stage, surface diameter, or histological grade of the lesion and lymph node metastasis. A significant percentage of cases had either carcinoma in situ (31%) or atypical hypertrophic dystrophy (19%) in the epithelium adjacent to the infiltrating carcinoma. Koilocytotic atypia suggestive of human papilloma virus infection was present in the adjacent epithelium in 47% of the cases. This study suggests that thickness of the neoplasm is a valid predictor for the presence or absence of lymph node metastasis in vulvar squamous cell carcinoma; it may be more useful than neoplastic depth of invasion in this regard.