Pigmented Lesions of the Nail Unit

Nail Apparatus Melanoma: Current Management and Future Perspectives

Nail apparatus melanoma (NAM) is a rare type of cutaneous melanoma that belongs to the acral melanoma subtype. NAM is managed principally in accordance with the general treatment for cutaneous melanoma, but there is scarce evidence in support of this in the literature. Acral melanoma is genetically different from non-acral cutaneous melanoma, while recently accumulated data suggest that NAM also has a different genetic background from acral melanoma. In this review, we focus on recent advances in the management of NAM. Localized NAM should be surgically removed; amputation of the digit and digit-preserving surgery have been reported. Sentinel lymph node biopsy can be considered for invasive NAM for the purpose of accurate staging. However, it is yet to be clarified whether patients with metastatic sentinel lymph nodes can be safely spared completion lymph node dissection. Similar to cutaneous melanoma, immune checkpoint inhibitors and BRAF/MEK inhibitors are used as the first-line treatment for metastatic NAM, but data on the efficacy of these therapies remain scarce. The therapeutic effects of immune checkpoint inhibitors could be lower for NAM than for cutaneous melanoma. This review highlights the urgent need to accumulate data to better define the optimal management of this rare melanoma.

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.

Pigmented Nail Lesions: When to Observe, When to Biopsy, When to Widely Excise, and When to Amputate?

Pigmented nail lesions are challenging problems. The differential diagnosis is broad and ranges from common self-limiting conditions, such as subungual hematoma and infection, to potentially fatal conditions, such as subungual melanoma. Clinical assessment and adjuncts, such as dermoscopy and imaging, are usually insufficient to establish a diagnosis, and a nail bed biopsy is often required. However, this is not an innocuous procedure and may result in permanent nail deformity. In addition, subjecting every patient with nail pigmentation to a biopsy will result in an unacceptably high rate of negative test results. Furthermore, histopathologic diagnosis of subungual melanoma remains challenging for several reasons. Once the diagnosis of subungual melanoma is established, the definitive treatment is controversial because the existing guidelines have largely been adapted from those for cutaneous melanoma. This review presents an approach to the diagnosis and management of pigmented subungual lesions and subungual melanoma, in particular, on the basis of the latest available evidence.

Hyperplastic melanocytes with chromosomal aberrations in surrounding skin of subungual melanoma: fluorescence in situ hybridization analysis using whole-slide digital imaging

AIMS

Subungual melanoma (SUM) is increasingly being treated with conservative surgery. Consequently, the evaluation of resection margins has increased in importance. However, in several cases it is difficult to distinguish the in-situ lesion of SUM from hyperplastic melanocytes in surrounding skin. We examined whether PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry and fluorescence in situ hybridization (FISH) labeling of CCND1 (11q13), RREB1 (6p25), MYB (6q23), and centromere 6 (CEP6) genes differentiated SUM from hyperplastic melanocytes.

METHODS AND RESULTS

We reviewed specimens of 36 SUM cases and compared PRAME immunostains of invasive melanoma, melanoma in situ, and hyperplastic melanocytes. PRAME-positive cases accounted for 90.5% of invasive melanoma, 88.9% of in situ melanoma, and 59.4% of hyperplastic melanocyte specimens. While invasive and in situ melanomas in more than half of examined cases were diffusely positive, this was found for only 9.4% of hyperplastic melanocyte cases. Four-colored FISH using whole-slide digital imaging was used to analyze positive detection rates and changes in chromosomal aberrations. The FISH positive detection rate was 100% in invasive melanomas, 94.7% in melanomas in situ, and 66.7% in hyperplastic melanocytes. The number of RREB1 (6p25) signals per cell was significantly amplified following tumor progression.

CONCLUSION

Hyperplastic melanocytes in the surrounding skin of SUM, considered morphologically non-neoplastic, showed chromosomal aberrations similar to those in melanoma. Such cells are also thought similar to the field cells of acral melanomas. Thus, whole-slide digital imaging is a technique that allows the evaluation of individual melanocyte lesions by FISH.

The pharmacotherapeutic management of nail unit and acral melanomas

INTRODUCTION

Acral and nail unit melanomas are rare subtypes of melanoma, which have poor prognoses. Current guidelines for optimal treatment are lacking. Recent clinical trials have evaluated new pharmacotherapeutic agents for melanoma treatment, with dramatically improved survival rates; however, studies on acral and nail unit melanomas are limited in comparison to trials on cutaneous melanoma.

AREAS COVERED

This is a comprehensive review of the literature regarding the available treatment options for acral and nail unit melanomas, with consideration of safety and tolerability.

EXPERT OPINION

Programmed cell death protein 1 inhibitors are more efficacious than cytotoxic T lymphocyte-associated antigen-4 blockers in acral and nail unit melanomas, although both are well-tolerated. Tyrosine kinase inhibitors have good clinical activity, however, data on safety is relatively limited. There is minimal data on high dose interferon α-2b and cyclin-dependent kinase 4 and 6 inhibitors, and efficacy and safety must be evaluated in future trials before they can be recommended for use in this patient population. Prospective clinical trials on acral and nail unit melanomas are lacking, and must be performed in large patient populations, with international collaboration likely necessary in order to enroll adequate participants.

Subungual Melanocytic Lesions in Pediatric Patients

The study of subungual melanocytic lesions can present challenges because of the clinical and histologic characteristics of the nail unit and the difficulty of performing nail biopsies and processing specimens. These lesions can be even more challenging in children due to differences in clinical and epidemiological profiles between the adult and pediatric populations. Many of the clinical features of subungual melanocytic lesions that would raise alarm in an adult do not have the same implications in children. Consensus is also lacking on when a nail biopsy is needed to rule out malignancy in the pediatric setting. In view of these considerations and the rarity of subungual melanoma in childhood, the recommended approach in most cases is a watch-and-wait strategy. Subungual melanocytic lesions in children may also show atypical histopathologic features that are not necessarily associated with aggressive behavior. Subungual melanoma is very rare in childhood, with just 21 cases described to date. None of the patients developed visceral metastasis or died as a result and the diagnosis was controversial in many of the cases. Considering the above and the significantly higher frequency and particular characteristics of longitudinal melanonychia with a benign etiology in children, subungual melanocytic lesions should be managed differently in this setting than in adults. In most cases, a watch-and-wait approach is the most appropriate strategy.

Mimical reconstruction and aesthetic repair of the nail after resection of subungual melanocytic nevus

Background

This study aimed to report the outcomes of mimical reconstruction and aesthetic repair of the nail.

Methods

When the pigmented bands were more than 1/2 the width of the whole nail, mimical reconstruction of the nail was performed, with a lateral toe pulp island flap covering the wound via the subcutaneous channel. If the pigmented bands were 1/4 to 2/5 the width of the entire nail, aesthetic repair of the nail was carried out by split-thickness excision under a microscope.

Results

The average age of patients at the time of surgery was 14.5 years. Five patients had lesions on their toes, while three had lesions on their fingers. There were no post-operative complications. All toenails of the five patients who had undergone mimical reconstruction exhibited a well-settled flap. The nails of the three patients who underwent aesthetic repair displayed no nail malnutrition or deformity, and all nails had an aesthetic appearance.

Conclusions

Both mimical reconstruction and aesthetic repair of the nail following resection of subungual melanocytic nevus are reliable and feasible. The “like tissue” repairs of complex nail defects appear to be satisfactory. All patients had excellent aesthetic outcomes.

Level of evidence

V

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-021-01423-9.

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.

Subungual Melanocytic Lesions: Key Clinical and Pathologic Concepts and Biopsy Techniques

Both dermatologists and pathologists sometimes find daunting the evaluation of melanonychia (especially subungual melanocytic lesions) because of the fear of performing nail surgery due to the risk of dystrophy, difficulties processing and interpreting nail biopsy specimens, and a general lack of experience in the field. Nevertheless, mastery of nail biopsy techniques, correct processing and orientation of specimens, and familiarity with the histologic particularities of the nail apparatus can attenuate the undoubted complexity and facilitate the tasks involved. Longitudinal excision is the biopsy technique that ensures the simplest histologic interpretation, and it is associated with a low risk of nail dystrophy when performed correctly. Clinical and epidemiological data are crucial. Subungual melanoma in childhood, for instance, is very rare and even lesions with atypical clinical and/or histologic features are probably benign. The presence of suprabasal melanocytes and other findings that would suggest malignancy at other sites are considered normal in the nail apparatus. Subungual melanoma shows a lentiginous pattern in the early stages of disease, and detection of an inflammatory infiltrate accompanying atypical lentiginous subungual lesions would appear to be one of the first diagnostic findings.

Melanoma of the Nail Apparatus: An Analysis of Patients' Survival and Associated Factors

BACKGROUND

There are no proper management guidelines for nail apparatus melanoma (NAM).

OBJECTIVE

This study aimed to describe the clinical features, the presence of locoregional and distant metastases and disease-free and overall survival of NAM treated at our institution.

METHODS

A retrospective cohort review of patients with single, primary localized histopathologically confirmed NAM was performed. Collected data consisted of patients' characteristics and tumor features. In addition, local recurrence, locoregional metastases, distant metastases, disease-free survival (DFS) and overall survival (OS) were used as the main outcomes in our analysis.

RESULTS

Thirty patients with NAM were included. The overall survival (OS) in our patients at 5 and 10 years was 85.6 and 73.4%, respectively. DFS was significantly higher in patients with primary tumor location in the hand and without tumor-infiltrating lymphocytes (p value = 0.01 and 0.04, respectively). The patients with in situ melanoma or Breslow thickness <1 mm had a significantly higher chance of DFS and OS (90.0 and 94.1% at 5 years, respectively) than those with thicker NAM (58.3 and 55.6% at 5 years, respectively). A total of 53.3% of 30 patients underwent primary excision and covering with a full-thickness skin graft, while 13.3% of our 30 patients underwent digit amputation. The patients who underwent excision and covering with a full-thickness skin graft showed a complete overall survival (100% at 5 years).

CONCLUSION

Primary tumor location in the hand and lower tumor thickness might be correlated with better patients' survival. The study results suggest that total amputation might not be necessary in all NAM cases.

Subungual Melanocytic Lesions: Key Clinical and Pathologic Concepts and Biopsy Techniques

Both dermatologists and pathologists sometimes find daunting the evaluation of melanonychia (especially subungual melanocytic lesions) because of the fear of performing nail surgery due to the risk of dystrophy, difficulties processing and interpreting nail biopsy specimens, and a general lack of experience in the field. Nevertheless, mastery of nail biopsy techniques, correct processing and orientation of specimens, and familiarity with the histologic particularities of the nail apparatus can attenuate the undoubted complexity and facilitate the tasks involved. Longitudinal excision is the biopsy technique that ensures the simplest histologic interpretation, and it is associated with a low risk of nail dystrophy when performed correctly. Clinical and epidemiological data are crucial. Subungual melanoma in childhood, for instance, is very rare and even lesions with atypical clinical and/or histologic features are probably benign. The presence of suprabasal melanocytes and other findings that would suggest malignancy at other sites are considered normal in the nail apparatus. Subungual melanoma shows a lentiginous pattern in the early stages of disease, and detection of an inflammatory infiltrate accompanying atypical lentiginous subungual lesions would appear to be one of the first diagnostic findings.

Oral and nail pigmentations: a useful parallelism for the clinician

Oral (OP) and nail (NP) pigmentations may occur simultaneously in physiological or pathological conditions, and may be a sign of underlying syndromic conditions that necessitate further investigation and treatment. Interestingly, the nail unit and oral cavity show a clinical parallelism that may help the clinician to conduct a correct examination and reach a prompt diagnosis. Both OP and NP can manifest clinically with focal or diffuse involvement and are due to external factors (exogenous pigmentation, drug-induced pigmentation) or endogenous factors (racial pigmentation, post-inflammatory pigmentation, nevi, genetic conditions and other disorders). The most concerning differential diagnosis is melanoma. Here we report the pathogenetic basis of OP and NP, together with the description of similar clinical features. To the best of our knowledge this is the first paper to summarize and describe the causes of pigmentation of both the oral cavity and the nail unit.

Macroscopic and dermoscopic evaluation used to differentiate subungual haemorrhage from melanocytic lesions

INTRODUCTION Subungual haemorrhage describes blood located between the nail matrix and nail plate caused by trauma. Lack of recalled trauma and long duration of nail pigmentation results in specialist referrals to rule out malignant pathology. AIM This report aims to describe the macroscopic and dermoscopic characteristics of subungual haemorrhage and to highlight its clinical differentiation from melanocytic lesions. METHODS Ninety-eight nails were assessed. Pigmentation in fifty-nine was due to subungual haemorrhage and was melanocytic in the remainder (identified by a longitudinal pigmented band). RESULTS Pigmentation in subungual haemorrhage had a clear proximal margin (73%) and the dermoscopic pattern was homogenous (97%), globular (78%) or streaky (34%). Features included peripheral fading (68%) and periungual haemorrhage (5%). Malignancy could be excluded in these cases by careful clinical evaluation. DISCUSSION A combination of macroscopic and dermoscopic characteristics help make a confident diagnosis of subungual haemorrhage. A two-stage process can aid clinical diagnosis by looking for known features of subungual haemorrhage and identifying absence of malignant features.