Desmoplastic and desmoplastic neurotropic melanoma

Abstract

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. Cancer 1998;83:1128‐1135. © 1998 American Cancer Society.

Desmoplastic Melanoma: Is There a Role for Sentinel Lymph Node Biopsy?

“…1,6,11,13,15,17 Nodal metastasis rates for non-DM of comparable thickness (>3 mm) are >25 %, which is far greater than the rates reported for DM. 1,7,11,23–29 Furthermore, Livestro et al 6 case-matched DM and non-DM patients by age, gender, and tumor thickness and showed that SLN metastasis rates were significantly lower for DM (8 %) compared with non-DM (33.8 %, p = .13). These results suggest that DM may behave in a biologically unique manner with a lower propensity for metastasizing to regional nodes.…”

“…1–4 DM is usually found on the head and neck of older males and often presents as a thicker tumor compared with nondesmoplastic melanoma (non-DM). 1,4–7 Despite the greater thickness, some studies report lower rates of nodal metastases compared with non-DM, suggesting a potentially different biologic behavior. 6,8 Interestingly, activating BRAF V600E mutations, present in ∼50 % of non-DM, are lacking in DM, providing further evidence for a different biology.…”

Rare Presentations of Primary Melanoma and Special Populations

“…45 Histologically, it is characterized by pleomorphic dermal spindle cells with a marked fibrogenic (stromal) component and may exhibit perineural invasion, intraneural invasion and neural transformation. Clinically, DM presents as a subtle plaque, nodule or dermal thickening which is often (46-93%) amelanotic 46 in chronically sun exposed areas and may be occasionally associated with adjacent lentigo maligna.…”

“…It is more common in older patients (median age 61 years). 45 Given the nondescript histological and clinical findings, DM is often initially misdiagnosed. As such, patients often present late with locally advanced, thicker lesions (mean Breslow depth 6.5 mm) with malignant cells extending deeply into the reticular dermis and subcutaneous tissue.…”

“…46 Studies show that a minimum of a 1 cm margin is needed to reduce local recurrences and improve overall survival. 45,48-50 However, the majority of DM are deep and the National Comprehensive Cancer Network (NCCN) guidelines recommend at least a 2 cm margin in tumors deeper than 2 mm. In order to overcome positive or close margins many authors recommend adjuvant radiation; however, given the rarity of this subtype of melanoma the evidence for such practice is based solely on retrospective reviews.…”