Sentinel node biopsy before and after wide excision of the primary melanoma

Background: Initially, the technique of sentinel node biopsy involved the u se of blue dye alone and was later supplemented with the use of an intraope rative probe after radiocolloid injection near the melanoma site. Ideally, it should be done before wide excision. To our knowledge, there is no infor mation in the literature regarding the applicability or reliability of this technique after wide excision. Methods: We conducted a retrospective review of 142 patients (1993-1999) wi th melanomas greater than or equal to 1.0 mm or Clark's level greater than or equal to IV. Of these, 116 patients had prior biopsy only, and 26 had wi de excision. The mean melanoma thickness was 2.5 mm. The location of the pr imary lesion was in the upper extremity in 42 patients, the lower extremity in 33, the trunk in 49, and the head and neck area in 18. Results: The sentinel node was identified in 88 (93%) of 95 nodal basins us ing the blue dye alone and in 65 (98.5%) of 66 basins using dye plus probe. The sentinel node was positive in 35 (25%) of the 142 patients and 38 (24% ) of the 161 nodal basins. In a mean follow-up of 30 months of 115 basins w ith negative sentinel nodes, 3 (3%) later developed a palpable positive nod e in the same basin. In the group of dye alone, the sentinel node was ident ified in 40 (100%) of 40 extremity primaries and in 48 (87%) of 55 trunk an d head and neck primary lesions (P = .02). Nine (35%) of the 26 patients wi th previous wide excision (25 with primary closure or skin graft, 1 with fl ap rotation) and 10 (32%) of 31 of nodal basins had a positive node; in 8 o f the 9 patients, the positive node was also the sentinel node. The only pa tient with a positive node incidentally removed along with a histologically negative sentinel node was the one with a previous wide excision and flap rotation. Conclusions: Previous wide excision of the melanoma does not appear to nega te the reliability of sentinel node biopsy, provided that no flap rotation was used to cover the defect.