Sentinel Node Mapping in Vulvovaginal Melanoma Using SPECT/CT Lymphoscintigraphy

We report 2 cases of vulvovaginal melanoma in which sentinel node mapping, performed using Tc-99m filtered sulfur colloid SPECT/CT lymphoscintigraphy, added important information to that provided by planar imaging and played a critical role in surgical planning and subsequent management. In the first case, lymphoscintigraphy planar imaging showed only foci of tracer uptake in the right groin and an equivocal focus in the left groin. SPECT/CT precisely localized these radioactive foci to the right and left inguinal sentinel nodes. The patient then underwent bilateral inguinal sentinel node sampling. In the second case, F-18 FDG PET/CT performed prior to lymphoscintigraphy demonstrated a moderately FDG-avid right inguinal lymph node that was indeterminate in nature. SPECT/CT revealed this lymph node to be a radioactive sentinel lymph node that was seen in the right groin on planar imaging. The patient then underwent right inguinal sentinel node sampling. Because pathologic study showed metastasis to the sentinel node, a planned pelvic exenteration was canceled, and the patient was referred for systemic treatment. Preoperative SPECT/CT lymphoscintigraphy is ideal for mapping the unpredicted lymphatic drainage pathways within the complex pelvic anatomy and this technique may also be used in the preoperative workup of other gynecologic malignancies.