Desmoplastic and desmoplastic neurotropic melanoma: experience with 280 patients.

BACKGROUND: It has been suggested that desmoplastic melanoma (DM) and desmoplastic neurotropic melanoma (DNM) are associated with worse prognoses and higher local recurrence rates than other forms of melanoma. In the current study, a large series of patients with DM and DNM treated at a tertiary referral center was reviewed.
METHODS: For 190 patients with DM and 90 patients with DNM accrued over a 10-year period, clinical features were recorded and all available histopathology was reviewed. The associations between clinical and pathologic variables, biologic behavior, and eventual outcome were analyzed.
RESULTS: The male-to-female ratio was 1.75:1 and the median patient age 61 years. The median tumor thickness was 2.5 mm, and 44% of cases were amelanotic. Five-year survival was 75%. Significant predictors of overall survival were a high mitotic rate (P=0.003) and tumor thickness (P=0.011). All the DNMs exceeded 1.5 mm in thickness and were graded as Clark's level IV or V. There was a significant increase in local recurrence when neurotropism was present (P < 0.001). The rate of local recurrence was not higher for DM than for other cutaneous melanomas.
CONCLUSIONS: There was no statistically significant difference in survival for patients with DM and those with DNM, and overall survival for both was similar to that for patients with other cutaneous melanomas. However, there was a lower rate of regional lymph node metastasis at initial presentation and as the first recurrence for both DM and DNM. The local recurrence rate was higher when the surgical clearance margin was <1 cm and when neurotropism was present.