Comparative morphometric study on the depth of invasion in vulvar carcinoma

Various studies assess the significance of depth of invasion as an important prognostic factor in squamous cell carcinoma of the vulva. However, methodologic problems exist with regard to the measurement points. While the deepest point of invasion can be measured accurately, the upper reference point is arbitrarily chosen. The goal of the present study was to identify the method of measurement and the threshold value, allowing the clearest prognostic differentiation between groups of patients with vulvar carcinoma. The study involved 124 patients treated between 1971 and 1980, who had received identical treatment (simple vulvectomy followed by local and inguinal irradiation) and identical histopathologic workup (large-scale sections). Beginning with the deepest point of tumor invasion, comparative measurement was carried out with three different points of reference: to the basement of the most superficial dermal papilla (method A), to the surface of the tumor (method B), and to the basement membrane of the deepest rete ridge (method C). The data were used to determine differences in specified end points. The results and conclusions are as follows: (1) The morphometrically determined degree of tumor invasion has prognostic significance. (2) Measurement of tumor thickness (method B) prognostically differentiates patient groups better than measurement of invasion from the most superficially lying epithelial papilla (method A), if classified into tumors up to and over 0.5 cm. (3) Patients with superficial invasive vulvar carcinomas up to 0.5 cm can be further prognostically differentiated into two groups, when measuring depth of invasion from the deepest rete ridge (method C), and classifying into tumors up to and over 0.3 cm.