Frequently, the overlying epithelium is eroded or ulcerated which helps to explain their frequent confusion with squamous cell carcinoma. Microscopically, the lesion shows proliferation of atypical melanocytes along the dermoepidermal junction with extension into the squamous epithelium. The atypical melanocytes may be epithelioid, spindled or mixed and occur singly or in clusters. The infiltrative component is usually nevoid or spindled. Determination of the tumor thickness is based on a system proposed by Chung et al. since Clark's levels are inappropriate for mucosal sites of melanoma.
Most tumors are deeply invasive.
The differential diagnosss includes metastasis from other sites, poorly differentiated squamous cell carcinoma, sarcoma, lymphoma and blue nevus. It appears to be influenced by tumor size with lesions greater than 3 cm having a bad prognosis. Age, mitotic count, stage and location of the lesion do not influence survival. Benign melanosis of the vagina and cervix. Am J Obstet Gynecol.