Desmoplastic melanoma: is there a role for sentinel lymph node biopsy?

BACKGROUND: The utility of sentinel lymph node biopsy (SLNB) for desmoplastic melanoma (DM) is debated. We describe a large single-institution experience with SLNB for DM to determine clinicopathologic factors predictive of SLN metastasis.
METHODS: Retrospective review identified 205 patients with DM who underwent SLNB from 1992 to 2010. Clinicopathologic characteristics were correlated with SLN status and outcome.
RESULTS: Median age was 66 years, and 69 % of patients were male. Median Breslow thickness was 3.7 mm. In 128 cases (62 %), histologic subtype data was available; 61 cases (47.7 %) were mixed and 67 cases (52.3 %) were pure DM. A positive SLN was found in 28 cases (13.7 %); 24.6 % of mixed and 9 % of pure DM had SLN metastases. Multivariable analysis demonstrated that after controlling for age, histologic subtype correlated with SLN status [odds ratio: 3.0 for mixed vs pure, 95 % confidence interval: 1.1-8.7; p < .05]. Completion lymph node dissection was performed in 24 of 28 positive SLN patients with 16.7 % of cases having additional nodal disease. After a median follow-up of 6.3 years, 38 patients developed recurrence and 61 patients died. Positive SLN patients had a significantly higher risk of melanoma-related death compared with negative SLN patients (p = .01).
CONCLUSIONS: The overall risk for SLN metastasis for DM is 13.7 % and is significantly higher for mixed (24.6 %) compared with pure (9.0 %) DM. We believe that these rates are sufficient to justify consideration of SLNB for both histologic variants, especially since detection of SLN disease appears to predict a higher risk for melanoma-related death.