Sentinel Lymph Node Biopsy for the T1 (Thin) Melanoma: Is It Necessary?

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Abstract
The use of sentinel lymph node biopsy for the T1 melanoma is controversial. Recent reports have demonstrated that certain T1 melanomas are at increased risk for early regional metastases and late recurrence when compared with all thin melanomas. The purpose of this study was to review the authors' experience with wide excision and sentinel lymph node biopsy for certain patients with T1 melanoma. A retrospective analysis of 34 patients with T1 melanoma was completed over a 3-year period. Indications for sentinel lymph node biopsy included a Breslow thickness of less than or equal to 1 mm a Clark level of III or IV tumor ulceration, or tumor regression. Twenty-four patients met these criteria (13 men and 11 women). Mean age was 47.6 years (range, 23-88 years). Mean tumor thickness for all patients was 0.69 mm (range, 0.3-1.0 mm), 0.61 mm for the Clark level III patients (N = 15), and 0.72 mm for the Clark level IV patients (N = 9). Tumor ulceration was present in 1 patient and histological regression was present in 2 patients. Regional lymph node metastases were confirmed histologically in 2 of 24 patients (8.3%) in whom the thickness of the melanoma was 0.9 mm and 1 mm. Both patients have died of metastatic melanoma. No recurrence has been demonstrated in the remaining 22 patients at the 2 to 5-year follow-up. Current indications for sentinel lymph node biopsy for patients with T1 melanoma include tumors associated with Clark level IV or V invasion, ulceration, regression, a positive deep margin on initial biopsy, or previous melanoma. Acral lentiginous melanoma associated with at least a Clark level III invasion warrant sentinel lymph node biopsy. Superficial spreading or nodular melanoma larger than 0.9 mm should include sentinel lymph node biopsy regardless of other associated histological factors.