Sentinel node identification and the ability to detect metastatic tumor to inguinal lymph nodes in squamous cell cancer of the vulva

Abstract

Objectives The goal of this study was to identify one or more inguinal sentinel nodes in patients with primary squamous cell carcinoma of the vulva and to determine the ability of the sentinel node to predict metastasis to the inguinal lymphatic basin. Methods Techniques employing technetium-99m (Tc-99m) sulfur colloid and isosulfan blue dye were utilized to identify sentinel nodes in the inguinal lymphatic beds. Technetium-99m sulfur colloid was injected intradermally at the tumor margins 90–180 min preoperatively followed by a similar injection of isosulfan blue dye 5–10 min before the groin dissection. A handheld collimated gamma counter was employed to identify Tc-99m-labeled sentinel nodes. Lymphatic tracts that had taken up blue dye and their corresponding sentinel node were also identified and retrieved. A completion inguinal dissection was then performed. Each sentinel node was labeled as hot and blue, hot and nonblue, or cold and blue. The sentinel nodes were subjected to pathologic examination with step sections and nonsentinel nodes were evaluated in the standard fashion. Results Twenty-one patients with a median age of 79 were entered onto protocol and a total of 31 inguinal node dissections were performed. A sentinel node was identified in 31/31 (100%) groin dissections with the use of Tc-99m. Isosulfan blue dye identified a sentinel node in 19/31 (61%) groin dissections. Surgical staging revealed 7 patients with stage I disease, 5 with stage II disease, 5 with stage III disease, and 4 with stage IV disease. Lymph nodes in 9 groin dissections were found to have metastatic disease, and in 4 of these dissections, the sentinel node was the only positive node. Lymph nodes in 22 groin dissections had no evidence of metastasis. No false-negative sentinel lymph nodes were obtained (sentinel node negative and a nonsentinel node positive). Conclusion Tc-99m sulfur colloid is superior to isosulfan blue dye in the detection of sentinel nodes in inguinal dissections of patients with vulvar cancer. A sentinel node dissection utilizing Tc-99m alone can identify a sentinel node in all inguinal dissections. Pathologic examination with step sections has shown the sentinel node to be an accurate predictor of metastatic disease to the inguinal nodal chain.