Background/Objectives: Melanomas may develop de novo or in association with a pre-existing nevus (nevus-associated melanoma, NAM). Whether these subtypes differ in their clinical and biological behavior remains uncertain. We aimed to compare the clinicopathologic features and outcomes of NAM and de novo melanoma (DNM) in a large single-center cohort.Methods: We retrospectively analyzed 378 patients with invasive melanoma diagnosed between 2007 and 2021 at a tertiary referral center. Tumors were classified as NAM when histopathologic continuity with a nevus was present, and as DNM otherwise. Clinical, histologic, and prognostic variables were compared using univariate and multivariate analyses.Results: Of 378 melanomas, 90 (24%) were NAM and 288 (76%) were DNM. Patients with NAM were slightly younger (mean 52 vs. 54 years) and more often presented with tumors on the trunk (65.6% vs. 51.7%). NAMs exhibited lower Breslow thickness (0.55 vs. 0.84 mm), reduced mitotic activity (0.17 vs. 1.21/mm2), and less frequent ulceration (2.2% vs. 9.4%). Distant metastases occurred only in DNM (6.6%). Sentinel lymph node positivity (1.1% vs. 6.3%) and melanoma-specific mortality (0% vs. 0.69%) did not differ significantly. Multivariate analysis identified Breslow thickness and mitotic rate as independent predictors of subtype.Conclusions: NAMs present with more favorable histopathologic features than DNMs, yet long-term outcomes appear similar. These findings support divergent pathways of melanoma development and underscore the need for molecular and imaging studies to refine risk stratification and guide management.
**背景/目的：** 黑色素瘤可原发形成，也可在先前存在的痣基础上发生（痣相关黑色素瘤，NAM）。这两种亚型在临床和生物学行为上是否存在差异尚不确定。本研究旨在通过一个大型单中心队列，比较NAM与原发黑色素瘤（DNM）的临床病理特征及预后。 **方法：** 我们回顾性分析了2007年至2021年间在一家三级转诊中心确诊的378例侵袭性黑色素瘤患者。当肿瘤在组织病理学上与痣存在连续性时，归类为NAM，否则归类为DNM。采用单变量和多变量分析比较临床、组织学和预后变量。 **结果：** 在378例黑色素瘤中，90例（24%）为NAM，288例（76%）为DNM。NAM患者年龄稍轻（平均52岁 vs. 54岁），且肿瘤更多位于躯干（65.6% vs. 51.7%）。NAM表现出更低的Breslow厚度（0.55 vs. 0.84 mm）、更低的核分裂活性（0.17 vs. 1.21/mm²）以及更低的溃疡发生率（2.2% vs. 9.4%）。远处转移仅见于DNM（6.6%）。前哨淋巴结阳性率（1.1% vs. 6.3%）和黑色素瘤特异性死亡率（0% vs. 0.69%）无显著差异。多变量分析确定Breslow厚度和核分裂率是亚型的独立预测因素。 **结论：** NAM比DNM具有更有利的组织病理学特征，但长期预后似乎相似。这些发现支持黑色素瘤发展的不同途径，并强调了需要进行分子和影像学研究以完善风险分层并指导治疗。
Nevus-Associated and De Novo Melanoma: A Cross-Sectional Study on Prognostic Differences
肿瘤(癌症)患者之家