[Sentinel lymph node biopsy in malignant melanoma--an update]

The popliteal fossa - a problem zone for sentinel lymphonodectomy

BACKGROUND

The impact of lymphatic drainage to popliteal sentinel lymph nodes (SLNs) has yet to be explored in detail.

PATIENTS AND METHODS

We performed lymphoscintigraphy on 663 patients with cutaneous melanomas. The following day sentinel lymphonodectomy was performed. SLNs were studied on serial sections with both histology and immunohistochemistry.

RESULTS

166 patients had a melanoma located on the foot, the lower leg or the knee, i. e., the potential of lymphatic drainage to the popliteal lymph nodes. On lymphoscintigraphy, only 16 patients (9.6 %) showed popliteal SLNs. A popliteal SLN was surgically identified in only 6 of the 16 patients. The reason for the poor identification rate was exhausted radioactivity in the small popliteal nodes the day after lymphoscintigraphy. In 3 cases, popliteal SLN metastasis was diagnosed. All but one patient had an additional drainage to the inguinal lymph nodes; inguinal SLN metastasis was diagnosed in 7 patients. Even all 16 patients showed lymphatic drainage to iliac lymph nodes, metastasis in the pelvis was diagnosed in 4 patients.

CONCLUSIONS

Popliteal SLNs are observed in less than 10 % of the patients with melanomas of the distal leg. In the case of suspected popliteal drainage, lymphoscintigraphy should be performed on the day of sentinel lymphonodectomy because the radioactivity of the small and deeply situated popliteal nodes diminishes rapidly. With respect to complete lymphadenectomy, decision-making is difficult since three nodal basins (popliteal, inguinal and iliac) may harbor metastases.

Intraoperative Detektion von Sentinel-Lymphknoten beim malignen Melanom der Haut-Vitalfarbung allein versus Vitalfarbung plus Gammasonde. Intraoperative detection of sentinel lymph nodes in cutaneous malignant melanoma - blue dye alone versus blue dye plus gamma-detection

BACKGROUND

Compared with intraoperative sentinel lymph node identification using blue dye only, the introduction of a hand-held gamma probe has improved the identification rates. In this retrospective study, further aspects related to the introduction of gamma-guided preparation are analysed in detail.

PATIENTS AND METHODS

81 patients who underwent sentinel biopsy using the blue dye technique were compared to 247 patients whose operations were guided by blue dye and gamma probe.

RESULTS

After the introduction of radio-guided surgery, the sentinel node identification rate increased from 87.7 % to 99.2 % (P < 0.00001). The number of harvested sentinel lymph nodes increased from 1.4 +/- 0.9 to 1.8 +/- 0.09 (P < 0.00001). The "clinical false-negative rate" decreased from 15.8 % to 9.6 %. The percentage of positive completion lymphadenectomy decreased from 50 % to 24.6 %. The risk of postoperative seroma decreased as a consequence of gamma guided preparation (5.1 % versus 15 %, P = 0.01). Regarding overall survival and recurrence-free survival, there were no significant differences between both groups. The 5-year-probability of nodal basin failure was 7.9 % after negative sentinel biopsy and 25.3 % after positive sentinel lymphonodectomy plus consecutive completion lymphadenectomy.

CONCLUSIONS

Combined application of blue dye and gamma-probe improved sensitivity and decreased the risk of postoperative seroma. The probability of recurrence and survival was not influenced by the technique of intraoperative sentinel node identification.