Background

Most subungual melanocytic lesions in children are benign, but some are difficult to classify due to prominent lentiginous growth and high-grade cytologic atypia.

Objective

To characterize the clinicopathologic features of these rare lesions.

Methods

Subungual atypical lentiginous melanocytic proliferations from patients <20 years of age were collected for clinical and histopathologic review. Fluorescence in situ hybridization (FISH) was performed when possible.

Results

Eleven patients aged 2-19 years had expanding or darkening longitudinal pigmented streak(s) with or without Hutchinson sign. Microscopically, all revealed predominantly single-cell growth, pagetoid scatter, and poor circumscription. Eight (73%) cases showed focal or poor nesting, and 3 (27%) demonstrated confluence. Nuclear enlargement, hyperchromasia, and angulation were present in 8 (73%) cases, 7 (64%) cases, and 6 (55%) cases, respectively. One of 4 cases tested by FISH was positive. Three lesions recurred locally without other adverse outcome.

Limitations

Small sample size and short clinical follow-up. Two cases were examined in partial biopsies only.

Conclusion

Some subungual melanocytic lesions in children and adolescents are histologically indistinguishable from adult subungual melanoma in situ. While the biologic potential remains elusive, FISH might aid in risk stratification. Awareness of this rare group of lesions is crucial for facilitating future investigation into its biologic behavior.

中文翻译：

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儿童和青少年的非典型非典型性黑素性黑素细胞增生：临床病理研究

背景

儿童中大多数的门下黑素细胞病变是良性的，但由于明显的乳突生长和高度细胞学上的非典型性，有些难以分类。

客观的

表征这些罕见病变的临床病理特征。

方法

收集小于20岁患者的舌下非典型性慢性黑素细胞增生，以进行临床和组织病理学检查。如果可能，进行荧光原位杂交（FISH）。

结果

2-19岁的11例患者有或没有哈钦森征象的纵向色素性横纹增宽或变暗。在显微镜下，所有结果均显示主要为单细胞生长，页面状散布和较差的包膜。8例（73％）表现为局灶性或较差的筑巢，3例（27％）表现为融合。分别有8例（73％），7例（64％）和6例（55％）出现核增大，增生和成角。FISH检测的4例病例中有1例呈阳性。局部复发了三个病变，没有其他不良后果。

局限性

样本量小，临床随访时间短。仅对部分病例进行了两次活检。

结论

从组织学上看，儿童和青少年的一些舌下黑素细胞病变与成人的舌下黑素瘤在组织学上没有区别。尽管生物学潜力仍然难以捉摸，但FISH可能有助于进行风险分层。意识到这一罕见的病变组对于促进将来对其生物学行为的研究至关重要。