Desmoplastic neurotropic melanoma

Abstract

BACKGROUND.Several studies have suggested that desmoplastic neurotropic melanoma (DNM) is associated with higher local recurrence rates than other types of melanoma. The authors investigated the local recurrence rates for patients with DNM after surgery alone or surgery followed by radiotherapy (RT).METHODS.One hundred twenty‐eight patients with DNM were treated at the Sydney Melanoma Unit and the Sydney Cancer Center from 1996 to 2007. All patients underwent local excision, 27 patients also received RT. For both groups, clinical and pathologic features, treatment details, and local recurrence data were analyzed.RESULTS.The median age at diagnosis was 65.5 years. The ratio of men to women was 2.7:1. The head and neck was the most common location (51%). The median Breslow thickness was 4 mm, and 99% of patients had Clark Level IV or V primary tumors. Patients who received adjuvant RT had thicker tumors (P = .003), deeper Clark level invasion (P < .001), and narrower excision margins (P < .001). There were 8 local recurrences, including 6 (6%) in the surgery only group and 2 (7%) in the adjuvant RT group. A positive margin (P < .001) and head and neck location (P = .03) were significant predictors of local recurrence.CONCLUSIONS.The local recurrence rate in this series was lower than the rates reported in historic control groups and in the authors' previous temporal cohort. The results indicated that clear surgical margins are of paramount importance in minimizing local recurrence; when margins are compromised, the addition of RT may reduce local recurrence rates compared with historic controls. A prospective randomized trial is needed to quantify the risk reduction with adjuvant RT. Cancer 2008. © 2008 American Cancer Society.

Results of NCCTG N0275 (Alliance) – a phase II trial evaluating resection followed by adjuvant radiation therapy for patients with desmoplastic melanoma

“…Historical local recurrence rates (LRRs) for patients with DM are in the range of 20–50% 2, 3, 4, 5, 7, 8, though recent series have suggested potentially lower rates in selected patients (negative margins, non‐head and neck location, lack of perineural invasion, decreasing Breslow depth, etc.) 9, 10, 11, 12. This is in contrast to patients with other cutaneous melanomas who have LRRs of 1–13%, depending on tumor depth and the presence or absence of ulceration 13, 14, 15.…”

“…Of importance, the authors did identify two low‐risk groups in their analysis who could potentially omit adjuvant RT: (1) patients with negative margins, a non‐head and neck tumor location, and a Breslow depth ≤4 mm; and (2) patients with negative margins, a Breslow depth ≤4 mm, and no perineural invasion 15. Other authors have also noted patient populations at low risk for a LR who could potentially omit adjuvant RT 9, 10, 12. In general, these are patients with trunk or extremity DMs who are able to undergo a WLE with ≥2.0 cm margins with a thorough histopathologic review documenting negative margins.…”

“…With retrospective studies of adjuvant hypofractionated radiation therapy (RT) demonstrating a benefit in locoregional control in high‐risk non‐DM patients versus historical controls, as well as anecdotal and retrospective reports of good clinical results in high‐risk DM patients, a prospective phase II study was designed to determine if adjuvant hypofractionated RT would result in low LR rates in selected DM patients 9, 18, 19, 20, 21, 22, 23, 24, 25.…”

Desmoplastic Melanoma, Neurotropism, and Neurotrophin Receptors—What We Know and What We Do Not

“…20 In both of these studies, the potential for "skip lesions," in which the tumor extension along the nerves results in falsely negative margins in biopsies, was hypothesized to be the cause for the increase in local recurrence. Since then, the majority of studies have reported that neurotropism is not of significant prognostic relevance 13,[22][23][24] (summarized in chronologic order in Table 1); however, recently Scanlon et al 16 reported that PNI is associated with increased rates of local recurrence in both DM and non-DM cases. Future studies that attempt to determine the prognostic relevance of PNI would benefit greatly by laying out an explicit definition of neurotropism as PNI.…”

Rare Presentations of Primary Melanoma and Special Populations

“…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.…”