Desmoplastic Melanoma: Clinical Behavior and Management Implications.

INTRODUCTION: Desmoplastic melanoma is a rare variant of melanoma that has been reported to demonstrate unique clinical behavior when compared with other histological subtypes. In this study, we present the clinical course of patients with this unusual diagnosis. We hypothesized that desmoplastic melanoma would differ from nondesmoplastic melanoma with regard to its presentation, rate of regional metastasis, and recurrence pattern. METHODS: After institutional review board approval, a retrospective chart review was performed on all patients with a diagnosis of desmoplastic melanoma since 1998. The following data were collected: patient demographics, histopathological details of the lesion, initial treatment, and clinical course. In addition, the available slides were reviewed by a dermatopathologist. RESULTS: Twenty-eight patient charts were reviewed. Mean age at diagnosis was 65 years. Fifty-seven percent of patients were men, and 67% of the lesions originated from the head and neck. Of the 28 patients, 11 had pathology slides that were adequate for evaluation. Pure desmoplastic melanoma, defined by more than 90% of the specimen demonstrating desmoplastic features, was found in only 3 patients. Taking into account all cases, the mean Breslow thickness was 5.09 mm and ulceration was present in 12.5% of lesions. Regional disease was discovered in 18% of patients. The mean follow-up time was 43 months, and the overall recurrence rate was 32%. 66.7% of first recurrences were local. Two of 3 patients with pure desmoplastic melanoma developed regional metastasis. CONCLUSIONS: Our data largely support previous studies that suggest desmoplastic melanoma behaves differently compared with other histological subtypes. However, the incidence of regional disease among patients with pure desmoplastic melanoma appears to be higher in our study than in previous reports. Although this rare variant typically presents with advanced local disease, the rate of regional metastasis is less than what would be expected for similar thickness, nondesmoplastic cutaneous melanoma. The recurrence pattern is different compared with nondesmoplastic melanoma, and the most common site of recurrence is local. Discrepancy in the literature regarding the clinical behavior of this disease may be related to inconsistent pathological criteria for diagnosis. Further research will help clarify the optimal management of desmoplastic melanoma.