Melanoma-like features in pediatric longitudinal melanonychia: A systematic review and meta-analysis

BACKGROUND

Pediatric longitudinal melanonychia (LM) can exhibit atypical features that mimic red-flag signs for subungual melanoma in adults and lead to diagnostic uncertainty. Nail biopsy may be unnecessary if clinical inspection and dermoscopy suggest a benign nature.

METHODS

We searched PubMed and Embase from inception to February 2023 for studies of any design reporting either the number or proportion of clinical and dermoscopic features in at least five children (≤18 years) with LM. Non-English articles, reviews, and abstracts were excluded. We performed a systematic review and meta-analysis to collate all existing data.

RESULTS

A total of 1218 articles were screened and 24 studies with 1391 pediatric patients were included. Nevus was the most common diagnosis (86.3%). The most prevalent sites were fingernails (76.2%) and first digits (45.4%). Pooled proportions of common features were: dark-color bands (69.8%), multi-colored bands (47.6%), broad bandwidth (41.1%), pseudo-Hutchinson sign (41.0%), irregular patterns (38.1%), Hutchinson sign (23.7%), dots and globules (22.5%), nail dystrophy (18.2%), and triangular sign (10.9%). Outcomes included progression (widening or darkening, 29.9%), stability (23.3%), and spontaneous regression (narrowing or fading, 19.9%). Only eight cases of subungual melanoma in situ were reported, and no invasive melanomas were identified.

CONCLUSION

Although atypical characteristics are common in pediatric LM, the probability of malignant transformation is exceedingly low. Appropriate evaluation and management of pediatric LM includes careful clinical and dermoscopic inspection with attention to benign features followed by long-term interval follow-up.

An Evidence-Based Approach to Pediatric Melanonychia

Melanonychia including melanonychia striata in children poses a diagnostic dilemma. Atypical clinical features often raise the possibility of malignancy, and a nail unit biopsy may be recommended. Commensurate with atypical clinical features, the histopathology may also appear alarming. However, accumulating data illustrate that most cases of melanonychia striata are benign and suggest that an alternate approach is often warranted for pediatric patients. Herein, we review the existing data regarding pediatric melanonychia striata and offer an evidence-based approach to its evaluation and management.

Dermoscopic Evaluation of Longitudinal Melanonychia in Children: A Prospective Study

Background:

Longitudinal melanonychia (LM) is a worrisome sign in both children and adults. Nail apparatus melanoma (NAM) can be related to LM, but it is very rare in children. Dermoscopic signs of benign lesions in children can be similar to melanoma; therefore, it is important to review dermoscopy of LM in children to make the best decision in performing biopsy.

Aims:

Biopsy taking is very challenging in LM in children. Most lesions are benign in children. The aim of this study was to review dermoscopic signs of LM in children and compare them with adults.

Materials and Methods:

In this prospective study a total of 108 LM (35 children and 73 adults) were undergone dermoscopy of LM. Dermoscopic features were compared in children and adults; both for benign lesions proven by biopsy or follow up and melanomas diagnosed histopathologically.

Results:

Black background, black band color, band color diversity and pseudo-Hutchinson's sign were more frequent in children in comparison with benign adult melanonychia. Some children's dermoscopic features of LM such as broad band width, Band color diversity, Hutchinson's sign, gray band color, asymmetry of pattern, and regression were similar to melanoma, but we did not find any melanoma by biopsy and/or follow up among children. We also detected the newly described "zigzag" pattern in four children.

Conclusion:

Dermatologists should consider all dermoscopic features of a lesion, dermoscopic sign changes in follow-up, medical, and familial history of the patient in deciding to perform biopsy of LM in children.

Nail discoloration in pediatric skin of color patients

Nail pigmentation in children can cause significant anxiety in parents and clinicians. Different pigments of the nails, such as yellow, orange, and green, can all occur; however, this paper will focus on the dark pigments: brown, gray, and black pigmentation of the nails. Many causes of dark coloration of the nails exist; almost all causes in pediatric patients are benign and require no treatment. Melanoma is the one diagnosis that physicians do not want to miss. Fortunately, this is extremely rare in children.

Review article: Emerging issues in pediatric skin of color, Part 2

Dermatology for pediatric skin of color is the application of dermatology to the genetically diverse and distinctive segment of the pediatric population that includes children of non-White racial and ethnic groups with increased pigmentation including individuals of Asian, Hispanic/LatinX, African, Native American, Pacific Island descent, indigenous people among others with overlap in particular individuals, and mixtures thereof. The discipline of pediatric skin of color can be challenging with difficulty in diagnosis of common conditions due to underlying pigmentation, variations in common hair styling practices, and differences in demographics of cutaneous disease. Whereas some conditions are more common in children of color, other conditions have nuances in clinical appearance and therapeutics with regard to skin color. This article, the second of the series, focuses on inflammatory skin disease nuances, melanocytic disorders, and hypopigmented mycosis fungoides.

Clinicopathological diversity and outcome of longitudinal melanonychia in children and adolescents: analysis of 35 cases identified by excision specimens

AIMS

Longitudinal melanonychia in paediatric patients often represents a difficult diagnostic challenge, and studies emphasising its clinical and histopathological features are limited due to its low incidence in childhood.

METHODS AND RESULTS

We retrospectively analysed 35 paediatric cases identified by excision specimens on their clinicopathological features, and performed fluorescence in-situ hybridisation on 13 available cases. Fingernails (77.1%) were more likely to be affected. Total melanonychia and Hutchinson's sign were observed in 10 (28.6%) and 14 (40.0%) cases, respectively. Nail dystrophy at diagnosis was present in five cases. After complete excision of the lesions, four patients relapsed during follow-up (mean = 38 months). Seventeen cases were diagnosed as lentigines and 18 as naevi, among which 11 cases were categorised as lentigines/naevi with atypical melanocytic hyperplasia. Mild-to-moderate nuclear atypia, confluency of melanocytes, focal pagetoid spread and peri-ungual skin involvement were found in 25.7% (9 of 35), 40.0% (14 of 35), 40.0% (14 of 35) and 40.0% (14 of 35) of cases, respectively. Thirteen cases tested by fluorescence in-situ hybridisation showed no copy number aberration at the probed loci. There was a statistically significant difference in the following features between patients aged less and more than 10 years (P < 0.05): cytomorphology, mild-to-moderate nuclear atypia, confluency of melanocytes, focal pagetoid spread and melanocyte count.

CONCLUSIONS

Some concerning clinicopathological characteristics, which are signs indicative of melanoma in adults, are not uncommon in paediatric longitudinal melanonychia, especially in patients aged ≤ 10 years. Owing to the extremely low incidence of melanoma in paediatric longitudinal melanonychia, in most circumstances a more conservative clinical management strategy should be adopted.

Clinicopathological, immunohistochemical and fluorescence in-situ hybridisation features of early subungual melanoma: an analysis of 65 cases

AIMS

Very limited data are available concerning the clinicopathological and molecular features of early subungual melanoma (SM), especially with regard to the Asian population. The aim of this study was to investigate the clinical, histological, immunohistochemical and chromosomal features of early SM.

METHODS AND RESULTS

Fifty-two in-situ and 13 thin (Breslow thickness ≤1.0 mm) SM cases were retrospectively reviewed. All patients presented with longitudinal melanonychia involving a single digit, and the thumb was the most affected digit (35 of 65, 53.8%). Microscopically, most cases showed small to medium nuclear enlargement (58 of 65) and mild to moderate nuclear atypia (57 of 65). Hyperchromatism and irregular contours of nuclei were persistent features in all cases. The variation of melanocyte count (the number of melanocytes per mm dermal-epithelial junction) ranged from 31 to 255. Intra-epithelial mitoses were identified in 34 cases (52.3%). Statistically, features of in-situ lesions including higher melanocyte count (>70), presence of multinucleated melanocytes, inflammatory infiltrate and cutaneous adnexal extension, were associated with early invasion. Melan-A, human melanoma B (HMB)45, mouse monoclonal melanoma antibody (PNL2) and SOX10 antibodies (>95.0%) showed superior diagnostic sensitivity to S-100 protein (83.1%). Fluorescence in-situ hybridisation (FISH) results were positive in 15 of 23 successfully analysed cases.

CONCLUSIONS

To the best of our knowledge, this is the largest single-institution study of early SM in an Asian population, and the largest cohort tested by FISH. Early SM mainly showed small to medium nuclear enlargement and mild to moderate nuclear atypia. High melanocyte count, hyperchromatism and irregular contours of nuclei and intra-epithelial mitoses are crucial diagnostic parameters. Immunohistochemistry, especially SOX10 staining, and FISH analysis are valuable in the diagnosis of SM.

A case of adult-onset longitudinal melanonychia due to nail matrix compound nevus

A case of adult-onset longitudinal melanonychia caused by a compound nevus is described. Longitudinal melanonychias are mainly caused by melanocytic activation (hypermelanosis), lentigo (benign melanocytic hyperplasia), nevus, and melanoma. Nevi are more commonly seen in children than adults; however, melanocytic activation, atypical melanocytic proliferation, and melanoma are more frequent in adults. The majority of nail matrix nevi causing longitudinal melanonychia first appear in childhood and are junctional. Rarely, compound nevi are reported to cause longitudinal melanonychia in childhood.

Pediatric nail disorders: a review

PURPOSE OF REVIEW

Nail disorders represent an uncommon subset of complaints seen in pediatric dermatology. There is a wide array of disorders that can affect the nail unit in children, including infectious, inflammatory, neoplastic, congenital, and traumatic processes. In order to enhance familiarity with pediatric nail conditions, we review the background and treatment of the more common entities seen in pediatric onychology, including onychomycosis, onychomadesis, nail psoriasis, trachyonychia, longitudinal melanonychia, onychophagia, and onychocryptosis.

RECENT FINDINGS

Nail involvement in pediatric patients with psoriasis may indicate increased risk for both overall disease severity and the development psoriatic arthritis. In the evaluation of longitudinal melanonychia, the clinical findings that raise concern for subungual melanoma in adults are often found in benign nail unit nevi in children. In the systemic treatment of pediatric onychomycosis, new data raises the possibility that laboratory monitoring may be approached differently. In the approach to onychophagia, emerging pharmacotherapies include N-acetylcysteine.

SUMMARY

Most nail disorders in pediatric patients have an overall favorable prognosis. However, nail abnormalities can lead to patient and parental anxiety, decreased quality of life, pain, and functional impairment. Clinicians should be aware of these more common diverse entities in order to identify them and apply state of the art management for these issues. Additionally, the reader will learn factors related to these nail disorders, which may require systemic work-up and/or specialist referral.

A Review of Nail Dystrophies for the Practitioner

GENERAL PURPOSE

To provide information about nail pathology from its clinical presentation, pathophysiologic origin, clinical diagnosis, diagnostic testing, and treatment.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, NPs, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant should be better able to:1. Review the etiology of and risk factors for the various types of nail pathology.2. Describe the clinical manifestations, diagnosis, and treatment of the various types of nail pathology.

ABSTRACT

Nail pathology has a range of etiologies, from biomechanical trauma to systemic associations. Within this review, nail pathology is examined from a clinical presentation, pathophysiologic origin, clinical diagnosis, diagnostic testing, and treatment standpoint. Nail dystrophy reveals both systemic and exogenous pathology, reinforcing the value of assessing nails during the medical examination.