[Tumour regression is not predictive for higher risk of sentinel node involvement in thin melanomas (Breslow thickness < or = 1 mm)]

Eight Years' Experience of Sentinel Lymph Node Biopsy in Melanoma Using Lymphoscintigraphy and Gamma Probe Detection After Radiocolloid Mapping

BACKGROUND

Isosulfan blue dye peripheral injection is used in preoperative sentinel lymph node (SLN) identification alone or, to increase sensitivity, in conjunction with radiocolloid mapping. However, isosulfan blue dye has certain drawbacks and limitations.

OBJECTIVE

This study assesses the authors' experience of SLN biopsy using only radiocolloid tracer.

MATERIALS AND METHODS

Between 2000 and 2008, 218 patients underwent SLN biopsy with radiocolloid mapping, preoperative localization by lymphoscintigraphy and intraoperative confirmation by gamma probe in primary malignant cutaneous melanoma.

RESULTS

Mean Breslow index was 2.1 mm. The SLN biopsy success rate was above 98% at all sites and 87% in head and neck locations. The 5-year overall survival rate was 90% and that of 5-year disease-free survival was 80%. False-negative rate, with a mean follow-up time of 41 months, was 5.5%.

CONCLUSION

Sentinel lymph node biopsy can be successfully performed in patients with melanoma using only radiocolloid tracer without blue dye staining. In circumstances where blue dye cannot be used such as head and neck tumors, allergic reactions and pregnancy, radiocolloid tracer mapping alone is not a loss of chance for patients with melanoma.

Outcome of sentinel lymph node biopsy and prognostic implications of regression in thin malignant melanoma

Thin melanomas with partial or complete regression may provide clues about antitumor immunity, but their management remains controversial. We have characterized the management and clinical outcomes of regressed thin (<1 mm) T1a melanomas and hypothesized that regression increases the risk of regional metastases when compared with nonregressed thin melanomas. A prospectively collected clinical database was reviewed, and T1a melanomas with regression were identified. Histology, surgical approach, outcome, and survival were evaluated. The primary outcome measures were sentinel node positivity, subsequent lymph node metastasis, and survival. A total of 75 patients with T1a or in-situ melanomas were grouped into three subsets. Group 1: 35 underwent a sentinel node biopsy (SNBx), none of which were positive. No patients developed nodal recurrence. The 5-year survival of this group was 93%, with a median follow-up of 52 months. Group 2: 31 were followed up without SNBx; two developed regional nodal disease (6.5%), neither of whom died of subsequent distant disease. The 5-year survival was 89%, with a median follow-up of 38 months. There was no significant difference in the survival between groups 1 and 2. Group 3: nine patients presented with metastatic disease concurrent with a regressed thin melanoma. These patients had a median survival of 2.3 years and a 4-year survival estimate of 22%. Regression should not be used as an indication for SNBx in T1a melanomas; we recommend that such patients be managed with wide local excision and a long-term clinical follow-up. The poor prognosis of thin regressed primary melanoma with simultaneous metastatic disease may indicate the existence of immune escape phenotypes supporting melanoma progression.