Abstract：
Longitudinal melanonychia (LM) is a pigmented band extending from the matrix to the distal edge of a nail. It is caused by increased production of melanin within the matrix, and integration into the nail plate. The origin of this production is usually benign, due to activation, hyperplasia or proliferation of melanocytes normally present in the matrix. In some cases, however, LM is the manifestation of a subungual melanoma, the diagnosis of which must be made early. Biographical, clinical and dermoscopic criteria make it possible to suspect melanoma and decide whether to perform biopsy. None of these criteria, however, are specific and definitive diagnosis requires pathologic examination of a matrix biopsy. The biopsy technique should enable reliable histological study while limiting the risk of secondary nail dystrophy. Initial resection should ideally involve the entire lesion. Complete elevation of the nail plate enables the lesion to be precisely located. Lesions up to 3 mm can be removed by longitudinal resection biopsies without significant sequelae. In more extensive lesions, incision or tangential (\"shave\") biopsy can be performed without impairing prognosis. In clinical presentations strongly suggestive of melanoma, immediate complete resection of the entire nail unit may be proposed.
摘要：
纵向黑甲（LM）是从基质延伸到指甲远端边缘的色素带。它是由基质中黑色素的产生增加引起的，并集成到钉板中。这种生产的起源通常是良性的，由于激活，正常存在于基质中的黑素细胞的增生或增殖。在某些情况下,然而,LM是甲下黑色素瘤的表现，必须及早诊断。传记,临床和皮肤镜标准使得怀疑黑色素瘤并决定是否进行活检成为可能.这些标准都没有，然而,明确的诊断需要进行基质活检的病理检查。活检技术应能够进行可靠的组织学研究，同时限制继发性指甲营养不良的风险。初始切除应理想地涉及整个病变。指甲板的完全抬高使病变能够精确定位。可以通过纵向切除活检去除高达3mm的病变，而没有明显的后遗症。在更广泛的病变中，切开术或切向（“剃须”）活检可在不影响预后的情况下进行。临床表现强烈提示黑色素瘤，可以建议立即完全切除整个钉单元。
