Limitations and challenges of nail unit dermoscopy in longitudinal melanonychia

To the Editor: We read with interest the article by Ohn et al1 on dermoscopic features of nail matrix nevi (NMN) in adults and children. We agree that establishing the nature of adult and pediatric longitudinal melanonychia can be challenging. Dermoscopy may be a useful adjunct in some cases. However, unlike in the skin, nail plate dermoscopy does not permit analysis of the pigment origin in the nail matrix epithelium. In this regard, we would like to issue a word of caution. We have treated biopsy-proven pediatric nail apparatus melanoma in situ (NAMis) and adult NAMis with notably inconspicuous dermoscopic features (which, taken alone, may have been inappropriately reassuring).

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