Intraoperative lymphatic mapping and sentinel lymph node biopsy for Merkel cell carcinoma

Background: Merkel cell carcinoma is a rare cutaneous neoplasm which commonly spreads to the regional lymph nodes. The feasibility of identifying the sentinel node in patients with clinically node-negative Merkel cell carcinoma was evaluated. Methods: Sentinel lymphatic mapping was performed in 18 patients with stage 1 Merkel cell carcinoma using the combination of isosulphan blue dye and Tc-99m-radiolabelled sulphur colloid. Patients with tumour metastasis in the sentinel node underwent complete dissection of the remainder of the lymph node basin. Results: Eighteen patients underwent removal of 35 sentinel nodes. Two patients demonstrated metastatic disease in the sentinel lymph nodes; complete dissection of the involved nodal basin revealed no additional positive nodes suggesting that the sentinel lymph node had been identified. The node-negative patients received no further surgical therapy, with no evidence of recurrent disease in the sentinel nodal basin at a median of 7 months' follow-up. Conclusion: Sentinel node biopsy is feasible in patients with Merkel cell carcinoma. It call be used to stage patients and provides important prognostic information. In those with subclinical nodal disease, it may direct early regional lymphadenectomy but the effect of such surgery on survival remains unclear.