Clark Level (168) Chung Depth of Invasion (167) Breslow Tumor Thickness (169)
I Intraepithelial Intraepithelial <0.76 mm
II Into papillary dermis ≤1 mm from granular layer 0.76–1.5 mm Superficial invasion
III Filling dermal papillae 1.1–2.0 mm from granular layer 1.51–2.25 mm Intermediate invasion
IV Into reticular dermis >2 mm from granular layer 2.26–3.0 Intermediate invasion 2.
The superficial spreading melanoma tends to remain relatively superficial early in its development.
3.
The nodular melanoma, which is the most aggressive, is characterized by a raised lesion that penetrates deeply and may metastasize widely.
In one of the largest reported series, more than one-fourth of the cases of melanomas were macroscopically amelanotic (158). Vulvar melanoma tends to spread early, not only lymphatically but also hematogenously.
Staging The FIGO staging used for squamous lesions is not applicable to melanomas because the lesions are usually much smaller and the prognosis is related to the depth of tumor invasion rather than to the diameter of the lesion (162,165,166). The leveling system established by Clark et al. for cutaneous melanomas is less readily applicable to vulvar lesions because of the different skin morphology (166). The vulvar skin lacks a well-defined papillary dermis. Breslow measured the thickest portion of the melanoma from the surface of intact epithelium to the deepest point of invasion (167). This system is more adequate for the vulva. Chung et al. proposed a modified system that retained Clark’s definitions for levels I and V but arbitrarily defined levels II, III, and IV, using measurements in millimeters (165). A comparison of these systems is shown in Table 38.7.
The revised 2009 AJCC staging for cutaneous melanoma indicates that tumor thickness remains the primary determinant of the T staging, but mitotic rate was integrated to subcategorize T1 tumors in addition to the presence of ulcerations. Specific immunohistochemistry criteria for the detection of micrometastases were included. The number and volume of metastatic nodes, site(s) of distant metastatic disease, serum lactate dehydrogenase level, and sentinel node results remained part of the staging (168).
Treatment With better understanding of the prognostic significance of the microstage, some individualization of treatment developed. Treatment of vulvar melanoma continues to be controversial, in part because of the lack of large prospective studies, which makes it difficult to draw conclusions regarding its behavior and best treatment. Treatments are guided by experience from cutaneous melanoma and squamous cell carcinomas of the vulva. Paralleling the trend toward more conservative surgical management of cutaneous melanoma, there is a shift toward more conservative management of vulvar melanoma (163,164,169–171).