Dermoscopic evaluation of melanonychia

Abstract

The prevalence of melanonychia is approximately 1%, and it is a common symptom encountered in daily practise. However, it may also be the first symptom of melanoma of the nail apparatus. Evaluation of adult melanonychia with clinical information and clinical images is sometimes difficult for clinicians. Dermoscopic observation provides important information based on the algorithm method. Melanonychia in children requires a different approach, because dermoscopic features observed in adult nail apparatus melanoma are generally observed in benign pediatric cases.

Should we biopsy melanonychia striata in Asian children? A retrospective observational study

“…Currently, a lack of consensus is identified on clinical, dermoscopic, and histopathological criteria on which to base management decisions . The clinical features of benign causes of melanonychia in children can mimic the clinical features typically associated with subungual melanoma in adults (eg, new onset melanonychia, sudden changes in appearance, Hutchinson's sign) . Histologic features are also not well defined and can result in heterogeneous diagnoses between reporting pathologists, especially for pathologists unfamiliar with reporting nail matrix biopsies in children .…”

“…Signs of a subungual melanoma causing melanonychia may include uneven, irregular bands with multiple colors and indistinct edges . Hutchinson's sign, characterized by extension of pigment to the adjacent nail folds, and the presence of nail dystrophy are also highly suggestive of subungual melanoma . Pseudo‐Hutchinson's sign, described as pigmentation seen through the translucent cuticle and nail folds, is common in children with melanonychia and may be mistaken for Hutchinson's sign …”

“…5,6 Hutchinson's sign, characterized by extension of pigment to the adjacent nail folds, and the presence of nail dystrophy are also highly suggestive of subungual melanoma. 7,8 Pseudo-Hutchinson's sign, described as pigmentation seen through the translucent cuticle and nail folds, is common in children with melanonychia and may be mistaken for Hutchinson's sign. 8 The sudden appearance of a longitudinal pigmented band on a single nail, particularly in an adult, or change in the appearance of a previously stable pigmented band may warrant a nail matrix biopsy to exclude an underlying melanoma.…”

Melanonychia striata: clarifying behind the Black Curtain. A review on clinical evaluation and management of the 21st century

“…In melanonychia striata due to melanocytic hyperplasia in the nail matrix, dermoscopy often shows a gray background and regular, parallel, longitudinal, homogeneous brown to black lines which are usually darker than those seen in melanonychia striata due to melanocytic activation . The presence of a brown background overlaid by longitudinal lines irregular in their thickness, spacing, color, or parallelism, erosion of the nail plate, and the micro‐Hutchinson sign is highly suggestive of a nail apparatus/subungual melanoma . In patients with any such atypical or concerning features, a nail matrix biopsy for the histologic examination should be considered.…”

“…Nail matrix biopsy should be avoided if possible because of the possibility of permanent nail dystrophy resulting from the procedure . This aspect is especially true in the pediatric age group as melanonychia striata rarely represents a nail apparatus in situ and invasive melanoma . Prolonged follow‐up is mandatory for early detection of possible malignant changes.…”