IDENTIFICATION OF SENTINEL LYMPH-NODE IN MALIGNANT-MELANOMA BY PREOPERATIVE LYMPHOSCINTIGRAPHY AND INTRAOPERATIVE GAMMA-PROBE GUIDANCE

Aim: The sentinel lymph node (SLN) has shown to reflect the histologic features of the remainder of the lymphatic basin in patients with mel anoma and is of considerable prognostic relevance. Aim of the study wa s to localize the SLN pre- and intraoperatively by means of lymphoscin tigraphy and gamma probe guidance. Methods: 38 patients with histologi cally proven malignant melanoma (tumor thickness >0.75 mm) were preope ratively examined by injecting 40 MBq Tc-99m-Nanocoll intradermally ar ound the lesion. The first lymph node identified was marked on the ski n. immediately after scintigraphy patients were referred to the operat ion room and intraoperatively mapped using a handheld gamma probe, Act ivity of the SLN and of the adjacent nodes was measured ex vivo. After excision of the SLN, the lymphatic basin was re-checked for radioacti vity and activity of the SLN and oi the adjacent nodes was re-measured after removal. Results: The hottest reading was found in all patients in vivo and ex vivo in the preoperatively marked lymph node. Morpholo gically (macroscopically, ultrasound, CT) ail nodes were unsuspicious. Histologically, in 8 patients metastatic involvement of the lymph nod e was found which led to a wide exploration of the lymphatic basin wit h consecutive lymph node excision in 7 patients. Conclusion: The findi ngs suggest that combined preoperative lymphoscintigraphy and intraope rative mapping with a gamma probe is a powerful approach for exact loc alization of the SLN. Diagnostic detection of the SLN may have conside rable impact for patient management, since extended lymph node dissect ion may be confined to patients presenting with positive SLN.