Proposal for modified inguinofemoral lymphadenectomy derived from investigation of anatomic distribution of sentinel and metastatic nodes in vulvar cancer

Abstract

ObjectiveWe aimed to develop a less invasive inguinofemoral lymphadenectomy (IFL) approach for vulvar cancer based on the investigation of the anatomic distribution of sentinel and metastatic nodes.MethodsPatients with vulvar cancer treated by surgery between 1995 and 2019 were retrospectively reviewed. A seven‐field method was adopted to assign the anatomic locations for lymph nodes removed via IFL or sentinel node biopsy. Only patients with nodal metastasis or sentinel nodes were included.ResultsA total of 102 patients with eligible data were analyzed. Nodal metastasis was confirmed in 118 groins undergoing IFL; sentinel node detection succeeded in 46 groins. The medial‐inguinal field had the highest rate of nodal metastasis involvement (59.3%, 70/118) and sentinel nodes present (73.9%, 34/46). The inferior‐femoral field was involved only in one groin with quadruple‐field metastases. The lateral‐inguinal field was not involved in any groin. Neither the lateral‐inguinal nor the inferior‐femoral field presented sentinel nodes.ConclusionThe lateral‐inguinal and inferior‐femoral fields of the groins have a low risk of developing nodal metastasis. Therefore, a modified IFL preserving these fields can be established to reduce surgical morbidity without sacrificing its therapeutic effect.

Sonographic localisation and description of inguinofemoral lymph nodes in patients with vulvar squamous cell carcinoma

“…Inguinofemoral LNs are located within the region outlined by the femoral triangle, also known as the Scarpa's triangle 16 . The boundaries of the femoral triangle include the inguinal ligament superiorly, the medial border of the sartorius muscle laterally and the medial border of the adductor longus muscle medially 17 . The roof of the femoral triangle is formed by the fascia lata 17 .…”

“…Although the femoral triangle defines structures deep to the fascia lata, the same boundaries can be used as a guide for the extent of a sonographic assessment of inguinofemoral LNs 16,19 . There is a paucity of studies reporting the anatomic distribution of inguinofemoral nodes 17 . There is however consensus that the inguinofemoral LNs, are categorised into superficial and deep groups, which are separated by the fascia lata 19,20 …”

“…The superficial inguinofemoral LNs range in number from ~12 to 17 7,12,21 . They are divided into the inguinal and femoral (sub‐inguinal) groups 17 (Figure 1D). Superficial inguinal LNs run more transversely across the groin, parallel and inferior to the course of the inguinal ligament 22 .…”

“…The expected areas of lymphatic drainage from the perineum and genitals are firstly the superficial inguinofemoral LNs in the superomedial quadrant/zone and subsequently the external iliac LNs 16 . Hence, the superomedial zone (zone 1) has the highest risk of involvement of nodal metastases from vulval cancer 17 . The location of any LNs with sonographic features of malignancy, the presence of any extra‐nodal extension of tumour and the relationship of the LN to surrounding vessels should be noted for biopsy and surgical planning 10 .…”

“…Using a high frequency linear transducer (10–18 MHz) with the patient positioned supine and legs in a frog‐leg position, systematic sonographic B‐mode, and colour Doppler imaging of the inguinofemoral region is performed. The area for sonographic assessment of inguinofemoral LNs should extend from the inguinal ligament region (2 cm superior to the groin crease) to 3–4 cm inferior to the groin crease, which should correspond to the apex of the femoral triangle 17 . Sonographic imaging of this region should be performed in longitudinal, transverse, and oblique planes.…”