Potential applications of intraoperative lymphatic mapping in vulvar cancer

Objective: We describe early results of and potentially important anatomic findings with intraoperative lymphatic mapping in patients with vulvar cancer. Methods: Isosulfan blue was injected into the dermis at the leading edge of the vulvar lesion in 21 patients. One to five minutes later a standard groin incision was made and carried to the superficial fascia. After gentle dissection, the afferent lymphatic channel and/or sentinel lymph node was identified by its bright blue color. The sentinel node was removed and then the superficial inguinal lymphadenectomy was completed. Results: The 21 patients, ranging in age from 23 to 85 years (median, 52 years), underwent intraoperative lymphatic mapping. The clinical stages were as follows: T₁in 9, T₂in 10, T₃in 1, and unknown in 1 patient with a prior wide local excision. Two patients had palpably suspicious nodes. Ten patients had lateral lesions, and 11 had midline tumors. Eight of the 11 patients had bilateral groin dissections, making a total of 29 groins dissected. The sentinel node was identified in 18 patients (86%) and in 19 groins (66%). Five patients had unilateral node metastases, and one patient had bilateral node metastases. A sentinel node was found in five of these seven groins. A total of 238 nodes were removed (median, 8.2 nodes per groin). In no case was a nonsentinel node positive if the sentinel node was negative. In one patient the only metastasis was microscopic tumor in the sentinel lymph node. In one case, the sentinel node was found below the cribriform fascia. The sentinel node could not be identified in either groin in one patient with a clitoral primary; however, dye was seen in lymphatic channels passing under the symphysis pubis. The sentinel node was identified in various sites within the superficial compartment including lateral to the femoral artery and at the extreme medial border of the dissection. No complication related to the injection of isosulfan blue was seen. Conclusion: Intraoperative lymphatic mapping is safe and simple to perform and may help identify the sentinel node, define the extent of superficial inguinal lymphadenectomy, and identify uncommon anatomic variations.