Lymphatic Mapping in Treating Patients With Stage I or Stage II Cancer of the Vulva

DISEASE CHARACTERISTICS: * Histologically confirmed invasive squamous cell carcinoma of the vulva that is greater than 1 mm in thickness as measured from the nearest rete peg * Tumor size must be 2-6 cm * No recurrent disease * Prior excision of the primary disease or a history of carcinoma in situ of the vulva allowed * No tumor extending into the urethra, anus, vagina, rectum, or bladder * No grossly suspicious or inflamed groin nodes on physical exam * No grossly infected primary tumors PATIENT CHARACTERISTICS: Age: * Any age Performance status: * GOG 0-3 Life expectancy: * Not specified Hematopoietic: * Not specified Hepatic: * Not specified Renal: * Not specified Other: * No other invasive malignancy within the past 5 years except non-melanomatous skin cancer * No known hypersensitivity to phenylethane compounds PRIOR CONCURRENT THERAPY: * No prior cancer therapy that contraindicates therapy in this study Biologic therapy: * Not specified Chemotherapy: * Not specified Endocrine therapy: * Not specified Radiotherapy: * Not specified Surgery: * See Disease Characteristics * No prior groin dissection