Longitudinal melanonychia (LM) is a brown-black pigmented band extending from the matrix up to the distal part of the nail plate, normally induced by melanocyte activation, lentigines, nevi, and malignant melanomas.¹ Exogenous pigments can also cause melanonychia, but they usually do not form regular linear bands. Herein, we report a case of childhood LM caused by exogenous pigmentation.

中文翻译：

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表现为儿童纵向黑色素沉着的外源性色素沉着。

纵向黑色素瘤（LM）是一条棕黑色色素带，从基质延伸至指甲板的远端，通常由黑色素细胞活化，扁豆素，痣和恶性黑色素瘤诱发。¹外源性色素也可引起黑色素沉着症，但它们通常不形成规则的线性条带。在本文中，我们报告了由外源性色素沉着引起的儿童期LM病例。