Sentinel lymph node biopsy for ocular adnexal melanoma.

BACKGROUND

We sought to update our prior report of findings on sentinel lymph node biopsy (SLNB) and predictors of a positive SLN in patients with conjunctival or eyelid melanoma.

METHODS

We reviewed the records of all patients with ocular adnexal melanoma who underwent SLNB at one institution during 2000-2015. We determined rates of positive and false-negative findings on SLNB, primary tumour features correlated with positive findings and rate of nodal recurrence (false-negative event) after negative findings.

RESULTS

The study included 51 patients, 31 with conjunctival and 20 with eyelid melanoma. These patients include 30 patients who underwent SLNB during 2000-2008, described in our previous report, and 21 additional patients who underwent SLNB during 2008-2015. There were 30 women and 21 men with median age at SLNB of 62 years (range, 24-83). The nodal basins most commonly sampled were intraparotid (27 patients) and level II (14 patients). Ten patients had positive SLNB findings. Compared to tumours with negative findings, tumours with positive findings had greater median thickness (3.5 mm versus 2.2 mm, p = 0.04), greater median number of mitotic figures (6 versus 2, p = 0.03) and greater incidence of ulceration (80% versus 26%, p = 0.003). Perineural and vascular invasion were not significantly associated with positive findings. There were three false-negative events. Three patients (6%) had temporary marginal mandibular weakness which resolved spontaneously.

CONCLUSION

SLNB in patients with ocular adnexal melanoma is safe and identifies nodal micrometastasis in approximately 20% of cases. Histologic features associated with a positive SLN included greater tumour thickness, greater number of mitotic figures and ulceration.