Several recent studies examined the value of FDG-PET/CT in the detection of lymph node metastases. Kamran et al [27] retrospectively evaluated the performance of FDG-PET/CT prior to lymphadenectomy in 20 patients with primary vulvar SCC (size unspecified) and >1 mm of stromal invasion. They found that on a patient-by-patient basis, FDG-PET/CT demonstrated a sensitivity of 50%, specificity of 100%, PPV of 100%, and NPV of 57.1%. Crivellaro et al [28] retrospectively evaluated 29 patients with clinical early-stage primary vulvar cancer (primary tumors <4 cm and stromal invasion >1 mm) who were imaged with FDG-PET/CT prior to lymphadenectomy. The sensitivity, specificity, PPV, and NPV of FDG-PET/CT was 53%, 85%, 73%, 76%, and 67% on a groin-based analysis, and 50%, 67%, 59%, 59% on a patient-based analysis, respectively. The authors concluded that FDG- PET/CT had low sensitivity and moderate specificity for detecting IFLN metastases in early-stage disease. Combination of radiocolloid (usually Tc-99m sulfur colloid) and blue dye (most commonly isosulfan blue 1%) has a superior SLN detection rate (97.7%) compared with either Tc-99m sulfur colloid (94%) or blue dye (68.7%) alone [21,23]. Radiocolloid is injected intradermally around the tumor 2 to 4 hours prior to surgery. Preoperative lymphoscintigraphy may help with approximate SLN localization, whereas the intraoperative handheld gamma probe allows more precise SLN detection and localization. Blue dye is injected in the operating room 15 to 30 Staging and Follow-up of Vulvar Cancer minutes prior the procedure and localizes transiently to SLN aiding intraoperative visualization and removal of blue-stained lymph nodes [6]. If the SLN is negative for metastatic spread on pathologic evaluation, lymphadenectomy is omitted [6]. If an ipsilateral SLN is not identified, complete lymphadenectomy is recommended [6].
Staging and Follow up of Vulvar Cancer. Several recent studies examined the value of FDG-PET/CT in the detection of lymph node metastases. Kamran et al [27] retrospectively evaluated the performance of FDG-PET/CT prior to lymphadenectomy in 20 patients with primary vulvar SCC (size unspecified) and >1 mm of stromal invasion. They found that on a patient-by-patient basis, FDG-PET/CT demonstrated a sensitivity of 50%, specificity of 100%, PPV of 100%, and NPV of 57.1%. Crivellaro et al [28] retrospectively evaluated 29 patients with clinical early-stage primary vulvar cancer (primary tumors <4 cm and stromal invasion >1 mm) who were imaged with FDG-PET/CT prior to lymphadenectomy. The sensitivity, specificity, PPV, and NPV of FDG-PET/CT was 53%, 85%, 73%, 76%, and 67% on a groin-based analysis, and 50%, 67%, 59%, 59% on a patient-based analysis, respectively. The authors concluded that FDG- PET/CT had low sensitivity and moderate specificity for detecting IFLN metastases in early-stage disease. Combination of radiocolloid (usually Tc-99m sulfur colloid) and blue dye (most commonly isosulfan blue 1%) has a superior SLN detection rate (97.7%) compared with either Tc-99m sulfur colloid (94%) or blue dye (68.7%) alone [21,23]. Radiocolloid is injected intradermally around the tumor 2 to 4 hours prior to surgery. Preoperative lymphoscintigraphy may help with approximate SLN localization, whereas the intraoperative handheld gamma probe allows more precise SLN detection and localization. Blue dye is injected in the operating room 15 to 30 Staging and Follow-up of Vulvar Cancer minutes prior the procedure and localizes transiently to SLN aiding intraoperative visualization and removal of blue-stained lymph nodes [6]. If the SLN is negative for metastatic spread on pathologic evaluation, lymphadenectomy is omitted [6]. If an ipsilateral SLN is not identified, complete lymphadenectomy is recommended [6].