Transected thin melanoma: Implications for sentinel lymph node staging.

Abstract

Indications for sentinel lymph node (SLN) biopsy in patients with thin melanoma (≤1 mm thick) are controversial. We asked whether deep margin (DM) positivity at initial biopsy of thin melanoma is associated with SLN positivity. Cases were identified using prospectively maintained databases at two melanoma centers. Patients who had undergone SLN biopsy for melanoma ≤1 mm were included. DM status was assessed for association with SLN metastasis in univariate and multivariate analyses. 1413 cases were identified, but only 1129 with known DM status were included. 39% of patients had a positive DM on original biopsy. DM-positive and DM-negative patients did not differ significantly in primary thickness, ulceration, or mitotic activity. DM-positive and DM-negative patients had similar incidence of SLN metastasis (5.7% vs 3.5%; P = 0.07). Positive DM was not associated with SLN metastasis on univariate analysis (OR 1.69, 95% CI: 0.95-3.00, P = 0.07) or on multivariate analysis adjusted for Breslow depth, Clark level, mitotic rate, and ulceration (OR = 1.59, 95% CI: 0.89-2.85; P = 0.12). For patients with thin melanoma, a positive DM on initial biopsy is not associated with risk of SLN metastasis, so DM positivity should not be considered an indication for SLN staging in an otherwise low-risk patient.