Sentinel node localization should be interpreted with caution in midline vulvar cancer.

OBJECTIVE: Carcinomas of the vulva situated on the midline or close to it, are supposed to have a bilateral lymphatic drainage. The aim of this study was to evaluate sentinel node identification in these tumors.

METHODS: Between April 2002 and February 2004, 17 patients with operable vulvar cancer situated on, or close to the midline were entered in a prospective study. All patients underwent sentinel node identification with (99m)Tc-labelled nanocolloid (preoperative lymphoscintigraphy and intraoperative use of a handheld probe). Depending on the surgeon, intraoperative blue dye was associated. Radical excision of the tumor and routine bilateral lymphadenectomy were then performed. Sentinel nodes were sent separately for histologic examination. Negative sentinel nodes on hematoxylin/eosine were further examined with immunohistochemistry.

RESULTS: One or more sentinel nodes were identified in the 17 patients and in 21 of the 34 groins. In 5 patients, the sentinel nodes were metastatic. There was no false negative (negative sentinel node and metastatic non-sentinel node). In 13 patients, lymphoscintigraphy and then intraoperative identification suggested a unilateral drainage of the tumor with sentinel nodes localized in only one groin. Among these 13 patients, 3 groins with no sentinel node identified contained in fact massively metastatic nodes.

CONCLUSION: Unilateral finding of a sentinel node in tumors of the midline does not preclude a metastatic node in the other groin. Lymph node assessment should remain bilateral in these lesions.