Diagnosis of Melanonychia

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.

Seven Plus One Steps to Assess Pigmented Nail Bands (Melanonychia Striata Longitudinalis)

Melanonychia striata longitudinalis might involve one or more fingers and/or toes and might result from several different causes, including benign and malignant tumors, trauma, infections, and activation of melanocytes that might be reactive or related to the pigmentary trait, drugs and some rare syndromes. This broad differential diagnosis renders the clinical assessment of melanonychia striata particularly challenging. Nail matrix melanoma is relatively rare, occurs almost always in adults involves more frequently the first toe or thumb. The most common nail unit cancer, squamous cell carcinoma / Bowen disease (SCC) of the nail matrix is seldom pigmented. Histopathologic examination remains the gold standard for melanoma and SCC diagnosis, but excisional or partial biopsies from the nail matrix require training and is not routinely performed by the majority of clinicians. Furthermore, the histopathologic evaluation of melanocytic lesions of the nail matrix is particularly challenging, since early melanoma has only bland histopathologic alterations. Dermatoscopy of the nail plate and its free edge significantly improves the clinical diagnosis, since specific patterns have been associated to each one of the causes of melanonychia. Based on knowledge generated and published in the last decades, we propose herein a stepwise diagnostic approach for melanonychia striata longitudinalis: 1) Hemorrhage first 2) Age matters 3) Number of nails matters 4) Free edge matters 5) Brown or gray? 6) Size matters 7) Regular or irregular and, finally, "follow back".

Incipient Melanonychia: Benign Finding or Occult Malignancy? A Case Report of Subungual Melanoma

Subungual melanomas are rare neoplasms that tend to debut as longitudinal melanonychia. They are primarily found in patients over 60 years of age and are usually diagnosed late, representing a diagnostic challenge. We present a case report of a 59-year-old female Hispanic patient who initially presented with melanonychia and was eventually diagnosed with subungual melanoma in situ. She was surgically treated and, after three months, remained healthy. Relevant risk factors, clinical and onychoscopic findings, diagnostic criteria, and treatment options are also discussed. Since many benign entities present similarly, high clinical suspicion is critical for diagnosing this entity.

Clinical and dermoscopic findings of benign longitudinal melanonychia due to melanocytic activation differ by skin type and predict likelihood of nail matrix biopsy

BACKGROUND

Longitudinal melanonychia (LM) is a common dermatologic finding in clinical practice with a broad differential diagnosis. Melanocytic activation is the most common LM etiology.

OBJECTIVE

To investigate clinical and dermoscopic differences of benign LM based on Fitzpatrick skin type and in biopsied vs. non-biopsied patients.

METHODS

A 10-year retrospective cohort of 248 benign LM cases at Weill Cornell Dermatology was identified and analyzed.

RESULTS

Darker-skinned vs. lighter-skinned patients had higher band width percentage (p=0.0125), lower band brightness (p<0.001), more band changes (p=0.0071), and received more biopsies (p=0.032). Biopsied (n=47) vs. non-biopsied patients (n=201) had less multidigit band involvement (p=0.0008), higher band width percentage (p=0.0213), lower band brightness (p=0.0003), and more band changes (p<0.0001). Darker skin types more often had brown vs. grey coloration on dermoscopy (p=0.0232). Mean band width percentage for all biopsied patients was 30.81% (range: 5.80%-100%).

LIMITATIONS

Single-center retrospective design. Subungual melanoma and other benign LM etiologies were not analyzed. Only 18.95% of patients received a biopsy.

CONCLUSION

Darker vs. lighter skin types more often present with darker and wider bands, brown vs. grey coloration on dermoscopy, and receive more biopsies. Multi-institutional studies on LM are needed to determine nail matrix biopsy criteria in different skin types.

Transient neonatal hyperpigmentation of the proximal nail fold in a Chinese infant: a case report

Cutaneous alterations are common in neonates and usually occur in the first few days of life. Most of these are transient and benign, appearing as physiological responses to birth. Skin pigmentation disorders are considered transitory dermatoses of newborn infants. Nail pigmentation manifests as asymptomatic brown to bluish-black skin pigmentation over the fingers and toes in newborns. Hyperpigmentation of the distal phalanx of both hands and feet is commonly found in dark-skinned newborns, but it is rare in fair-skinned newborns and East Asian populations. We herein describe a Chinese infant with transient neonatal hyperpigmentation of the proximal nail fold.