Sentinel lymph-node biopsy after previous wide local excision for melanoma

Objective: To document experience with sentinel lymph-node biopsy in patien ts who have already undergone a wide local excision for melanoma because in many centres previous wide excision has been a contraindication for sentin el lymph-node biopsy. Design: A prospective cohort study. Setting: A tertia ry care academic cancer centre. Patients: One hundred patients who presente d with cutaneous melanoma (depth >1 min or Clark level IV) after having und ergone wide local excision of the primary lesion that was not situated in t he head or neck. The follow-up was 3 years. Interventions: Sentinel lymph-n ode biopsy. Patients with truncal melanoma had preoperative lymphoscintigra phy to document the nodal basins at risk. Technetium-99m sulfur colloid (0. 5-1 mCi in 0.5 mL) was injected intradermally around the scar, and the sent inel lymph node was excised with the aid of a hand-held gamma detector. Out come measures: Accuracy of the biopsy and false-negative rates in this sett ing. Results: Of the 100 patients, 44 had truncal and 56 had extremity lesi ons. The average tumour depth was 3.47 mm and 3.07 mm respectively. Thirty- one patients had a sentinel lymph node positive for melanoma metastasis. Bi opsies were positive for melanoma in 18 (41%) truncal lesions and 13 (23%) extremity lesions. There were 3 (9%) false-negative sentinel lymph-node bio psies as diagnosed by clinically evident nodal disease subsequently appeari ng in the nodal basin subjected to biopsy. Two occurred in patients after l arge rotation flap closures of truncal lesions. The third patient had a sub ungual melanoma of the great toe. No disease,vas found in the 2 nodes disse cted. Two of the 3 false-negative biopsy results were obtained before seria l sections and immunohistochemical staining were used to examine the sentin el lymph nodes. Conclusions: Sentinel lymph-node biopsies can successfully identify clinically Occult nodal metastases in patients who have had previo us wide local excision of a melanoma, but the false-negative rate in patien ts with rotation flap closures should be taken into consideration.