Validation and application of the sentinel lymph node concept in malignant vulvar tumours

Inguinal lymphadenectomy, unilateral or bilateral, is widely used in cases of vulvar squamous cell carcinoma and melanoma but has a high morbidity. Sentinel lymph node (SLN) biopsy may be used in the management of these patients. The aims of this study were firstly to determine the reliability of SLN biopsy in predicting regional lymph node status and secondly to apply this technique in the routine clinical setting.

We prospectively studied 70 women with vulvar malignancies. The first 50 cases were of squamous vulvar cancer and were used to validate the SLN technique in this clinical setting (validation group). Once a satisfactory success rate had been achieved in the validation group, the SLN technique was applied to a further 20 patients with vulvar malignancies, i.e. squamous cell carcinoma (n=12) and melanomas (n=8) (application group). Dynamic and static images were acquired after the injection of 74-148 MBq of a colloidal albumin, and continued until SLN identification. Fifteen minutes before surgery, blue dye injection was administered in a similar manner to the radiocolloid. After incision, a hand-held gamma probe was used to find the SLN. In the validation group, dissection of the SLN was always followed by lymphadenectomy. In the application group, this procedure was only performed if the SLN was positive for metastases. For pathological staging, samples were evaluated using haematoxylin and eosin and immunohistochemistry.

In the validation group, lymphoscintigraphy allowed SLN detection in 49/50 patients (98%). Blue dye detected the SLN in 40/50 patients (80%). In 16 patients (33%), the SLN showed metastases in the pathology study. All 33 patients with negative SLN had regional lymph nodes negative for metastases (negative predictive value 100%). In the application group, lymphoscintigraphy showed drainage to an SLN in 19 out of 20 patients (95%) and blue dye demonstrated a stained SLN in 17/20 patients (85%). Seven of the 19 SLN-identified nodes (37%) were positive for metastases.

SLN identification permits the accurate pathological study of regional nodes and could reduce the high morbidity of current surgical treatment in vulvar tumour patients if the technique were to be adopted on a routine clinical basis.