Characteristics of sentinel lymph nodes' metastatic involvement in early stage of vulvar cancer

Background: Nodal involvement is one of the most significant prognostic factors in early-stage vulvar cancer. Aims: To determine the diagnostic accuracy of sentinel lymph node (SLN) detection in early-stage vulvar cancer and to describe the characteristics of metastatic lymph node involvement. Methods: Of 23 women with early-stage squamous cell vulvar cancer included in the study, five had lateral lesions and 18 had midline lesions. SLN detection was performed by using a radioactive tracer and blue dye, followed by radical vulvectomy or radical wide excision with uni/bilateral inguinofemoral lymphadenectomy, depending on tumour size and localization. SLNs were subsequently examined with haematoxylin-eosin and immunohistochemistry. Results: The SLN detection was successful in all 23 women (100%) and in 38 of 41 groins (92.3%) tested. The total number of SLNs was 67, with an average of 1.76 per groin. In total, 20 positive SLNs were detected in 14 of 23 patients. From a total of 20 positive SLNs, micrometastases were found in five SLNs and isolated tumour cells in one SLN. We experienced one case with a false negativity of SLN. Sensitivity, negative predictive value, accuracy and false negativity of SLN detection were 93.3%, 88.8%, 95.6% and 7.1% respectively. Conclusion: The SLN biopsy performed by an experienced team is a feasible method, with high accuracy in patients with early-stage vulvar cancer. Prognostic value of micrometastases should be confirmed in further studies.