Sentinel Lymph Node Biopsy after Previous Radical Lymphadenectomy of the Same Lymph Node Basin.

Purpose: This study aimed to determine the feasibility of preoperative lymphoscintigraphy and intraoperative radio-guided sentinel lymph node biopsy (SLNB) in patients previously submitted to complete lymphadenectomy (CL) in the same region. There is no current proposal to stage patients diagnosed with a new melanoma after SLNB if the regional lymph node (LN) was removed, preventing this specific population from adjuvant treatments due to understaging.Methods: We assessed six cases of patients with a previous cancer diagnosis (melanoma, breast, or thyroid cancer) who had undergone CL and later developed a new cutaneous melanoma in the same extremity submitted to CL. They underwent preoperative lymphoscintigraphy to locate the sentinel lymph node (SLN), followed by a radio-guided SLNB with the assistance of patent blue dye. A pathologist then evaluated the excised SLN.Results: We had 100% feasibility, all six patients had their SLN located, and three (50%) patients tested positive for metastasis in the excised LNs.Conclusions: All these patients met the criteria to undergo SLNB, but no previous reports demonstrated and corroborated the performance of this procedure in this situation. SLNB with expected drainage for regions previously submitted to a radical lymphadenectomy is a safe and effective procedure. A lymphoscintigraphy allows locating the SLN that is likely to be resected in surgery. In this scenario, we had a 50% positivity, providing how relevant and essential this information is for the prognosis and practical therapeutical approaches for this rare but relevant melanoma population.