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

Initially, the technique of sentinel node biopsy involved the use of blue dye alone and was later supplemented with the use of an intraoperative probe after radiocolloid injection near the melanoma site. Ideally, it should be done before wide excision. To our knowledge, there is no information in the literature regarding the applicability or reliability of this technique after wide excision.

We conducted a retrospective review of 142 patients (1993-1999) with melanomas > or =1.0 mm or Clark's level > or =IV. Of these, 116 patients had prior biopsy only, and 26 had wide excision. The mean melanoma thickness was 2.5 mm. The location of the primary 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.

The sentinel node was identified in 88 (93%) of 95 nodal basins using 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 with negative sentinel nodes, 3 (3%) later developed a palpable positive node in the same basin. In the group of dye alone, the sentinel node was identified in 40 (100%) of 40 extremity primaries and in 48 (87%) of 55 trunk and head and neck primary lesions (P = .02). Nine (35%) of the 26 patients with previous wide excision (25 with primary closure or skin graft, 1 with flap rotation) and 10 (32%) of 31 of nodal basins had a positive node; in 8 of the 9 patients, the positive node was also the sentinel node. The only patient with a positive node incidentally removed along with a histologically negative sentinel node was the one with a previous wide excision and flap rotation.

Previous wide excision of the melanoma does not appear to negate the reliability of sentinel node biopsy, provided that no flap rotation was used to cover the defect.