Subungual Melanoma: A Study of 124 Cases Highlighting Features of Early Lesions, Potential Pitfalls in Diagnosis, and Guidelines for Histologic Reporting

KS-NailMel-1: a novel cell line of nail apparatus melanoma

Nail apparatus melanoma (NAM) is a specific type of cutaneous melanoma that develops in the nail apparatus of the hands and feet. The prognosis for metastatic NAM is poor due to a lack of fully effective systemic therapies. However, the difficulty in obtaining a NAM model has hindered basic research aimed at discovering effective treatment strategies. In this study, we established a NAM cell line, named KS-NailMel-1, from a primary tumor located on the nail apparatus of the left ring finger of a 68-year-old Japanese female. The cells were successfully maintained for over 9 months, exhibiting a doubling time of 38.6 ± 1.94 h. KS-NailMel-1 displayed consistent growth, spheroid formation, and invasiveness, and was confirmed to be identical to the original tumor through short tandem repeat analyses, whole-exome sequencing, and immunohistochemistry. Western blotting of the cells demonstrated the protein expression of NECTIN4, which has recently attracted attention as a potential therapeutic target for melanoma. The KS-NailMel-1 cell line represents a valuable resource for basic and preclinical research on NAM, deepening our understanding of the tumor characteristics and facilitating the development of treatment strategies for this rare form of cancer.

Acral Melanoma in the Caucasian Population: A Comprehensive Cohort Study on Epidemiological, Clinicopathological, and Prognostic Features

BACKGROUND

Acral melanoma is associated with poor prognosis. Studying the characteristics and prognosis of Caucasian patients is crucial to understand the distinct features of this tumor.

OBJECTIVES

To analyze the epidemiological, clinicopathological, and prognostic features of acral melanoma in Caucasian patients.

METHODS

We conducted a retrospective, multicenter, cohort study of acral melanoma from a database across 20 hospitals from South Europe from January 2000 to December 2019.

RESULTS

A total of 733 acral melanomas were identified (median age, 67.5 years; 95.2%, Caucasians; 77.5% of which were located on the feet). Overall, 77.5% of cases were invasive melanomas. Foot melanomas had a higher proportion of invasive cases (80.8% vs 69.8%; p=0.003), stages III and IV at diagnosis (24.8% vs 11.7%; p<0.001), thicker Breslow depth (2.8mm vs 2.0mm; p=0.021) and a higher rate of positive sentinel lymph node biopsy (SLNB) (30.7% vs 15.7%; p=0.012). Thicker Breslow depth and later age of onset were risk factors for melanoma-specific survival. Thicker Breslow depth and ulceration were independent prognostic factors of relapse-free survival. Melanoma location and histopathological subtype were not associated with worse prognosis. Recurrences were a common finding (27.7%), with distant metastases appearing earlier than locoregional recurrences (1.32 years [IQR, 1.12-1.87] vs 2.14 years [IQR, 1.68-2.70]; p=0.015).

CONCLUSION

This study, the largest in a predominantly Caucasian population, underscores the unfavorable outcomes of acral melanoma. Foot melanomas exhibited delayed detection, increased invasiveness, thicker Breslow depth, increased SLNB involvement, and higher AJCC stages. The high recurrence rate and early distant metastases emphasize the critical role of intensive follow-up and routine imaging modalities to detect asymptomatic relapses.

Acral Melanoma in the Caucasian Population: A Comprehensive Cohort Study on Epidemiological, Clinicopathological, and Prognostic Features

BACKGROUND

Acral melanoma is associated with poor prognosis. Studying the characteristics and prognosis of Caucasian patients is crucial to understand the distinct features of this tumor.

OBJECTIVES

To analyze the epidemiological, clinicopathological, and prognostic features of acral melanoma in Caucasian patients.

METHODS

We conducted a retrospective, multicenter, cohort study of acral melanoma from a database across 20 hospitals from South Europe from January 2000 to December 2019.

RESULTS

A total of 733 acral melanomas were identified (median age, 67.5 years; 95.2%, Caucasians; 77.5% of which were located on the feet). Overall, 77.5% of cases were invasive melanomas. Foot melanomas had a higher proportion of invasive cases (80.8% vs. 69.8%; P=0.003), stages III and IV at diagnosis (24.8% vs. 11.7%; P<0.001), thicker Breslow depth (2.8mm vs. 2.0mm; P=0.021) and a higher rate of positive sentinel lymph node biopsy (30.7% vs. 15.7%; P=0.012). Thicker Breslow depth and later age of onset were risk factors for melanoma-specific survival. Thicker Breslow depth and ulceration were independent prognostic factors of relapse-free survival. Melanoma location and histopathological subtype were not associated with worse prognosis. Recurrences were a common finding (27.7%), with distant metastases appearing earlier than locorregional recurrences (1.32 years [IQR, 1.12-1.87] vs. 2.14 years [IQR, 1.68-2.70]; P=0.015).

CONCLUSION

This study, the largest in a predominantly Caucasian population, underscores the unfavorable outcomes of acral melanoma. Foot melanomas exhibited delayed detection, increased invasiveness, thicker Breslow depth, increased sentinel lymph node biopsy involvement, and higher AJCC stages. The high recurrence rate and early distant metastases emphaise the critical role of intensive follow-up and routine imaging modalities to detect asymptomatic relapses.

Evaluation and diagnosis of longitudinal melanonychia: A clinical review by a nail expert group

Longitudinal melanonychia (LM), a brown-black band on 1 or multiple nails, is commonly encountered in clinical practice. Benign LM may be due to exogenous (external, blood, bacterial, mycotic) or endogenous (melanin) pigment. Histopathologically, melanin-derived LM may result from overproduction of melanin by a normal number of melanocytes (melanocytic activation) due to physiologic, local, systemic, iatrogenic, syndromic, and drug-induced causes, or from benign (nail matrix nevus and lentigo) or malignant (nail unit melanoma [NUM]) melanocyte hyperplasia. A high index of suspicion is necessary to differentiate benign LM and NUM secondary to similarities in clinical presentation, especially in pediatric patients. Benign pediatric LM may exhibit clinical and onychoscopic features resembling adult NUM; thus, a conservative approach with close follow-up is recommended. Onychoscopy and histopathologic examination of nail clippings are useful initial diagnostic tools for LM, avoiding a biopsy or aiding in biopsy planning and patient triage. Nail matrix excisional biopsy is the gold standard for diagnosing/ruling out NUM. For suspicious LM, a nail matrix tangential excisional biopsy is recommended. A longitudinal excision is recommended for cases with a high-likelihood of invasive NUM, which provides information on tumor extension. Herein, we review the current literature to describe the evaluation and diagnosis of LM.

A Review of the Histopathology of Nail Unit Tumors Including Selection of the Optimal Surgical Sampling

Background

A wide variety of tumors can affect the nail unit, with some commonly mistaken as inflammatory or infectious diseases. Obtaining an optimal sample for histopathologic evaluation requires understanding of nail unit anatomy as well as the histopathology of the suspected nail tumor.

Summary

This review discusses clinical and histopathologic features of a subset of benign and malignant nail tumors, including subungual melanoma, nail unit squamous cell carcinoma in situ, nail unit squamous cell carcinoma, onychomatricoma, onychopapilloma, onychocytic matricoma, and onychocytic carcinoma. Optimal surgical sampling techniques for each lesion are presented.

Key Messages

In summary, the clinical and histopathologic features of several common and rare nail unit tumors and the optimal sampling techniques for each lesion are presented in this manuscript. Knowledge of the clinical and histopathologic features of these tumors informs the surgical approach to them and will produce the best patient outcomes.

Acral Melanoma Incidence and Survival Trends in 1990-2020: A Nationwide, Population-based Study

Acral melanoma is a clinical subtype of melanoma with high mortality, on which research is limited in scope. This study aimed to assess incidence trends and melanoma-specific survival rates for acral melanoma in the Swedish population from 1990 to 2020.This cross-sectional study included patients with an acral melanoma diagnosis from 1990 to 2020 from the nationwide, population-based Swedish Melanoma Registry. Analyses on acral melanoma melanoma-specific survival rates were adjusted for age, sex, histopathological subtype, and tumour thickness. Clinicopathological features and melanoma-specific survival rates were compared between diagnostic periods: 1990-1999, 2000-2009, and 2010-2020, respectively. Changes in standardized incidence rates in 1996-2020 were evaluated separately for males and females. In total, 1,000 acral melanomas in 999 patients were included in the study. No significant yearly change in standardized incidence rates for either males or females was observed, even though the absolute number of cases increased. Factors such as male sex, age ≥ 70 years, and Breslow thickness > 1.0 were independently linked to lower melanoma-specific survival. The 5-year melanoma-specific survival across the studied period ranged from 75.8% to 77.9% for females, and from 62.4% to 71.7% for males.

Depth of invasion analysis to predict acral melanoma outcomes

BACKGROUND

Acral melanoma is a subtype with worse outcomes. The Breslow micrometric measurement is the most critical parameter in planning treatment and predicting outcomes. However, for acral lentiginous melanoma, the value of the Breslow thickness is a matter of debate. Depth of Invasion (DOI) is a well-established measure for staging oral squamous cell carcinoma.

OBJECTIVE

This study compared DOI and Breslow thickness for predicting acral melanoma outcomes.

METHODS

We performed a retrospective cross-sectional study of 71 acral melanoma lesions subjected to sentinel lymph node biopsy at one Brazilian referral center.

RESULTS

Cox model univariate analysis showed that both DOI and Breslow thickness predicted melanoma specific survival (HR 1.12; p = 0.0255 and HR 1.144; p = 0.0006, respectively), although Kaplan Meier curve was only significant for Breslow (χ2 = 5.792; p = 0.0161) and not for DOI (χ2 = 0.2556; p = 0.6132). Sentinel lymph node status and presence or absence of ulceration also predicted specific survival in patients with acral melanoma (χ2 = 6.3514; p = 0.0117 and χ2 = 4.2793; p = 0.0386, respectively). Multivariate analysis, however, demonstrated that Breslow depth was the only independent parameter for predicting acral melanoma specific survival (HR 1.144; p = 0.0006).

CONCLUSION

Even though Breslow thickness remains the main predictor for survival in acral melanoma, it is not a perfect parameter. The introduction of DOI in this context opens new perspectives for predicting acral melanoma outcomes.

Long-term outcomes after amputation and sentinel node biopsy for subungual melanoma: A single-institution series

BACKGROUND

Subungual melanoma (SUM) is a rare tumor with historically poor outcomes. Thus, the benefit of proximal versus distal amputation in SUM remains unclear.

METHODS

We performed a retrospective review of our prospectively-maintained institutional melanoma database, including SUM and non-subungual acral melanoma (AM) patients who underwent sentinel lymph node biopsy (SLNB) between 1999 and 2022. All SUMs had distal joint or proximal amputations. Primary endpoints were overall survival (OS) and recurrence free survival (RFS). Kaplan-Meier estimates, and Cox univariate and multivariate analyses were performed. Tests were repeated on propensity score matched (PSM) populations in a 2:1 ratio.

RESULTS

123 patients underwent resection with SLNB for SUM (n ​= ​27) and AM (n ​= ​96). Median follow-up was 9.2 years. Unadjusted median OS was 149.1 months for AM and 198.1 months for SUM. In the PSM comparison, median OS and RFS remained comparable between SUM and AM (149.5 months versus 198.1 months; p ​= ​0.612). Sentinel node positivity was associated with significantly worse overall survival outcome (Hazard Ratio 5.49; CI (1.59-18.97), p ​= ​0.007). In the PSM population, male sex was also associated with a significant hazard of death (HR 3.00, CI (1.03-8.71), p ​= ​0.043). Proximal amputations were associated with significantly worse OS (p ​< ​0.002) and RFS (p ​< ​0.01) compared to distal amputations in SUM.

CONCLUSION

SUM was well-treated with distal amputations, and had better OS and RFS compared to SUM treated with proximal amputations. Sentinel lymph node status is an important prognostic factor for SUMs and AMs. SUMs can be treated similarly to AMs with comparably good long-term outcomes.

Proposal for the applicability of modified Breslow (measured from the basal membrane) as a predictor of survival and sentinel lymph node outcome in patients with cutaneous melanoma

BACKGROUND

Cutaneous melanoma is a neoplasm with a high mortality rate and risk of metastases to distant organs. The Breslow micrometric measurement is considered the most important factor for evaluating prognosis and management, measured from the granular layer to the deepest portion of the neoplasm. Despite its widespread use, the Breslow thickness measurement has some inaccuracies, such as not considering variations in the thickness of the epidermis in different body locations or when there is ulceration.

OBJECTIVE

To evaluate the applicability of a modified Breslow measurement, measured from the basal membrane instead of from the granular layer, in an attempt to predict sentinel lymph node examination outcome and survival of patients with melanoma.

METHODS

A retrospective and cross-sectional analysis was carried out based on the evaluation of slides stained with hematoxylin & eosin from 275 cases of melanoma that underwent sentinel lymph node biopsy from 2008 to 2021 at a reference center in Brazil.

RESULTS

Analysis of the Cox model to evaluate the impact of the Breslow measurement and the modified Breslow measurement on survival showed that both methods are statistically significant. Logistic regression revealed a significant association between both measurements and the presence of metastasis in sentinel lymph nodes.

CONCLUSION

Measuring melanoma depth from the basal membrane (modified Breslow measurement) is capable of predicting survival time and sentinel lymph node outcome, as well as the conventional Breslow measurement.

Acral Lentiginous Melanoma: A Clinicoprognostic Study of 149 Cases at a Single Institution

OBJECTIVE

The objective of this study is to investigate the epidemiological features, clinical characteristics, and pathological characteristics of acral lentiginous melanoma (ALM) and identify prognostic factors.

METHODS

A total of 149 patients diagnosed with ALM between August 2008 and December 2019 at the National Cancer Center (NCC) of China were retrospectively analyzed. Follow-up data on patient survival status were collected. Survival curves were generated using the Kaplan-Meier method, and statistical significance was assessed using the log-rank test. Additionally, a Cox proportional hazards model was constructed to identify prognostic factors.

RESULTS

All patients included in this study were of Chinese ethnicity, with an average age of 52.4 ± 14.8 years (range, 15-80 years) at the time of diagnosis. No gender predilection or genetic susceptibility was observed. The plantar region was the most frequently affected site among primary lesions. Notably, only 17 (11.4%) patients reported a history of trauma. Statistical analysis revealed that a lesion duration of ≤2.5 years, Breslow thickness >4.0 mm, high mitotic rate (>6 mm-2), presence of vascular invasion, and regional lymph node metastasis were identified as independent prognostic factors.

CONCLUSION

Our findings indicate that a lesion duration of ≤2.5 years, Breslow thickness >4.0 mm, high mitotic rate (>6 mm-2), presence of vascular invasion, and regional lymph node metastasis are significantly associated with a poorer prognosis for patients with ALM.

The utility of SOX10 in mixed type desmoplastic melanoma with lymph node metastasis of the spindle cell component: A cautionary tale of inattentional blindness

Desmoplastic melanoma (DM), a type of spindle cell melanoma separated into pure desmoplastic melanoma (PDM) and mixed desmoplastic melanoma (MDM) subtypes, can be a diagnostic challenge and easily confused for dermal scar, especially PDM. We report a 65-year-old white man who received a left thumb amputation after an initial biopsy for melanoma, an unclassified type with epithelioid morphology. The amputation and sentinel lymph node specimens were significant for residual melanoma with epithelioid morphology, dermal scar, and a slightly expanded "scar-like" capsular area in one of seven lymph nodes, which was diffusely positive for SOX10 on reflex sentinel lymph node immunohistochemical protocol. On re-review of the amputation "scar" like area, a subsequent SOX10 stain confirmed the diagnosis of MDM in this area with epithelioid and spindle cell morphology, significantly upgrading the tumor stage. We share this case to highlight: (i) MDM, although exceptionally uncommon, can result in a pure spindle cell lymph node metastasis, (ii) to encourage increased utilization of SOX10 to assess sentinel lymph node biopsies, especially in the context of melanomas with a spindle cell component, and (iii) share an example of inattentional blindness which was fortunately identified by reflex sentinel lymph node immunohistochemical protocols.

Looking Beyond the Hutchinson Sign: A Retrospective Study of Clinical Factors Indicating the Presence and Invasiveness of Nail Unit Melanoma in Patients With Longitudinal Melanonychia

BACKGROUND

The data underlying this article are available in the article.Longitudinal melanonychia (LM) presents a challenge because nail unit melanoma (NUM) must be considered as a differential diagnosis. Because nail matrix biopsy may result in nail dystrophy, it is important to distinguish NUM from LM.

OBJECTIVE

To provide evidence of previously reported clinical factors indicative of NUM in patients with LM.

METHODS

This was a retrospective study of patients who presented with LM and had biopsy-confirmed NUM from 2005 to 2021. Benign LM was either confirmed by biopsy or considered benign if followed without the need for biopsy. Clinical factors associated with LM and NUM were compared by multivariate regression.

RESULTS

A total of 177 patients (97 LM and 80 NUM) were included. Multivariate regression showed that high band color intensity (p = .0031), variegation (p = .0005), nail plate splitting (p = .0017), Hutchinson sign (p = .0027), and band change (p = .001) correlated with malignancy. Nail plate splitting was associated with Breslow thickness.

CONCLUSION

Malignancy should be suspected and biopsy performed in patients with LM and high band color intensity, variegation, nail plate splitting, Hutchinson sign, and band change.

Differences in the Clinical and Molecular Profiles of Subungual Melanoma and Acral Melanoma in Asian Patients

Subungual melanoma (SUM) is a rare type of malignant melanoma that arises beneath the nails. SUM is categorized as a type of acral melanoma (AM), which occurs on the hands and feet. SUM is an aggressive type of cutaneous melanoma that is most common among Asian patients. Recent studies reveal that SUM and AM might have different molecular characteristics. Treatment of melanoma relies on analysis of both clinical and molecular data. Therefore, the clinical and molecular characteristics of SUM need to be established, especially during metastasis. To define the mutation profiles of SUM and compare them with those of AM, we performed next-generation sequencing of primary and metastatic tumors of SUM and AM patients. Subungual location was a better independent prognostic factor than acral location for better overall survival (p = 0.001). Patients with SUM most commonly had the triple wild-type (75%) driven by GNAQ (58%) and KIT (25%) mutations, whereas patients with AM had BRAF (28.6%) and RAF (14.3%) molecular types of mutations. Single-nucleotide variations (SNVs) were more common in SUM than in AM, whereas copy number alterations (CNAs) were more common metastatic lesions of AM. Metastatic tumors in patients with SUM and AM showed increases in CNAs (43% and 80%, respectively), but not in SNVs. The number of CNAs increased during metastasis. When compared with AM, SUM has distinct clinical and molecular characteristics.

Adult and Pediatric Nail Unit Melanoma: Epidemiology, Diagnosis, and Treatment

Nail unit melanoma (NUM) is an uncommon form of melanoma and is often diagnosed at later stages. Approximately two-thirds of NUMs are present clinically as longitudinal melanonychia, but longitudinal melanonychia has a broad differential diagnosis. Clinical examination and dermoscopy are valuable for identifying nail findings concerning malignancy, but a biopsy with histopathology is necessary to confirm a diagnosis of NUM. Surgical treatment options for NUM include en bloc excision, digit amputation, and Mohs micrographic surgery. Newer treatments for advanced NUM include targeted and immune systemic therapies. NUM in pediatric patients is extremely rare and diagnosis is challenging since both qualitative and quantitative parameters have only been studied in adults. There is currently no consensus on management in children; for less concerning melanonychia, some physicians recommend close follow-up. However, some dermatologists argue that the "wait and see" approach can cause delayed diagnosis. This article serves to enhance the familiarity of NUM by highlighting its etiology, clinical presentations, diagnosis, and treatment options in both adults and children.

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.

Retrospective analysis of longitudinal melanonychia: A Chinese experience

OBJECTIVE

We aimed to analyze the clinical and histopathologic characteristics of longitudinal melanonychia (LM), explore the differences between adults and children, and propose some recommendations.

METHODS

Data on pigmentation, lentigo, subungual melanoma (SUM), and nail matrix nevus (NMN) were acquired for comparison.

RESULTS

Lesions on thumbs in the children's group were significantly fewer (p = 0.006) than in adults. Lesions on little fingers in children were more than in adults; the difference was statistically significant (p = 0.025). The widths of bands in adults were wider than in children (p < 0.001), and the duration and width were positively correlated (r = 0.474). There was more pigmentation in adults than in children; the difference was statistically significant (p = 0.005). NMN was reported in 56.1% children and 34.3% adults; the difference was statistically significant (p = 0.005). Adults had six SUM cases, whereas none in children; the difference was statistically significant (p = 0.006). The recurrence rate in adults was significantly higher than in children (p = 0.019).

CONCLUSION

The widths of bands increase with the course, indicating that LM may be progressive. The four pathological types have different distributions with age, and each type requires different treatment. The lower recurrence rate in children suggests that LM needs diagnosis and appropriate treatment as soon as possible.

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.

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.

PRAME expression in melanocytic lesions of the nail

BACKGROUND

Subungual melanoma can be diagnostically challenging. We evaluated the potential of PReferentially expressed Antigen for MElanoma (PRAME) immunoreactivity for differentiating benign from malignant nail melanocytic lesions.

METHODS

Sixty cases were identified (10 invasive melanomas, 8 melanomas in situ, 14 nevi, 12 cases of lentigo, and 16 of melanocytic activation). Percentage of PRAME-positive melanocytes was evaluated as follows: 0 no staining, 1+ 1%-25%, 2+ 26%-50%, 3+ 51%-75%, and 4+ >75%. A combined score of both percentage and intensity was also evaluated.

RESULTS

The difference in PRAME expression between malignant and benign lesions was statistically significant (p < 0.0001). The degree of PRAME expression significantly correlated with patients' age and clinical size. When based on percentage score, 61.1% of melanomas showed a 4+ score, 16.7% showed a 3+ score, 11.1% showed a 1+ score, and 11.1% was negative; 69.0% of the benign lesions was negative, 23.8% showed a 1+ score, 4.8% showed a 2+ score, and 2.4% showed a 4+ score. When the cutoff value for malignancy decreased from 4+ to 3+, the sensitivity increased from 61.1% to 77.8%, while specificity remained 97.6%. Combined score results were similar.

CONCLUSIONS

PRAME is a relatively sensitive and highly specific marker in differentiating benign from malignant nail melanocytic lesions. However, correlation with morphology is imperative.

Subungual melanoma with blue naevus-like morphological features: a clinicopathological retrospective analysis of nine cases

Melanocytic lesions in the nail apparatus are often challenging. Both subungual melanomas (SUM) and blue naevus of the nail are very rare. Occasionally, melanomas may mimic blue naevus histologically. Benign and malignant blue melanocytic lesions are commonly associated with G protein mutations, a distinct abnormality not associated with conventional subungual melanomas. We describe the clinical, histological and immunohistochemical features of nine cases of SUM with blue naevus-like morphological features. Mutations in exon 4 and 5 of GNAQ and GNA11 were investigated in two cases, which showed no mutations. RNA-seq of one case revealed unknown mutations along with mutations in ATM, METK and ARID1A. Our study delineates a variant of SUM that mimics blue naevus. Awareness of this pitfall is important when evaluating heavily pigmented lesions around the nail in order to avoid misdiagnosis. Appropriate sampling of subungual lesions and clinicopathological correlation are paramount to reach the correct diagnosis.

Immunohistochemistry for Preferentially Expressed Antigen in Melanoma in the Differential Diagnosis of Melanocytic Lesions of the Nail Apparatus

ABSTRACT

Nail unit melanocytic lesions present a unique set of diagnostic challenges because of the unfamiliarity with clinical assessment and the lack of experience with histologic examination. Because the first surgical specimen received in the pathology laboratory is typically small, sometimes suboptimal biopsy, the distinction between melanoma and its histologic mimics can be difficult. For this reason, there has been a continued interest in the development of ancillary markers that may assist in the differential diagnosis of nail unit melanocytic lesions. Upregulation of preferentially expressed antigen in melanoma (PRAME) has been reported to be a common event in melanomas, and PRAME immunohistochemistry has been shown to be helpful in evaluating various melanocytic neoplasms. In this study, we evaluated PRAME protein expression in a series of nail unit melanocytic lesions. Twenty-five nail unit melanomas (including small biopsy and amputation specimens) and 32 control benign melanocytic lesions were retrospectively retrieved. Nuclear PRAME staining was scored as percentage and intensity labeling. All melanoma cases showed the nuclear expression of PRAME, which was usually diffuse and strong. In specimens where the neoplastic cells are limited in number, the staining was restricted to the tumor cells, corresponding to the initial H&E impression. All control cases were negative for PRAME expression. PRAME expression is helpful in distinguishing between melanomas and other nail unit melanocytic lesions. This antibody also proved to be diagnostically valuable in detecting melanoma cells in small specimens with minimal disease.

Different progression pattern between acral and nonacral melanoma: A retrospective, comparative, clinicoprognostic study of 492 cases of primary cutaneous melanoma according to tumor site

BACKGROUND

There are limited data regarding the difference in progression pattern between acral melanoma and nonacral melanoma.

AIMS

The objectives of this study were to compare the progression pattern between acral and nonacral melanoma and evaluate its impact on clinical outcomes.

METHODS

Clinical and histopathological features, survival outcomes and prognostic factors of 492 patients with acral melanoma or nonacral melanoma were retrospectively evaluated using the Asan Medical Center database.

RESULTS

The male-to-female ratio and the mean age was 1:0.92 and 60.2 years for acral melanoma (n = 249), and 1:0.85 and 58.4 years for nonacral melanoma (n = 243), respectively. The demographic difference was not significant. Although prediagnosis duration was longer and the advanced stage was more common in acral melanoma than that in nonacral melanoma, the vertical growth phase was more common in nonacral melanoma than that in acral melanoma, whereas, the horizontal diameter is longer in acral melanoma than that in nonacral melanoma. Dissemination to lymph nodes was more common in acral melanoma than that in nonacral melanoma. Lymph node involvement was associated with deeper Breslow thickness in nonacral melanoma but not in acral melanoma. The degree of correlation of prediagnosis duration with horizontal diameter was remarkable in acral melanoma, but with Breslow thickness in nonacral melanoma. Overall survival was worse in acral melanoma than that in nonacral melanoma. The prognostic value of Breslow thickness was more remarkable in nonacral melanoma than that in acral melanoma.

LIMITATIONS

This study is a retrospective, single-center design.

CONCLUSION

Acral melanoma has a longer radial growth phase compared with nonacral melanoma. However, acral melanoma is commonly associated with lymph node dissemination which contributed to worse survival in acral melanoma than nonacral melanoma.

Acral lentiginous melanoma-Population, treatment, and survival using the NCDB from 2004 to 2015

Acral lentiginous melanoma (ALM) is a rare histological subtype of cutaneous malignant melanoma that typically presents on the palms and soles. To characterize the demographic and treatment characteristics of ALM, we used the National Cancer Database (NCDB) to describe a large multi-institutional cohort of ALM patients, consisting of 4,796 ALM patients from 2004 to 2015. ALM was more likely to be diagnosed at a later stage overall compared with non-ALM cutaneous melanomas, and more likely to be thicker, ulcerated, lymph node positive, and have lymphovascular invasion and positive margins. When stratified by stage, ALM had worse survival compared with non-ALM patients, most notably in stage III patients with 5-year survival of 47.5% versus 56.7%, respectively (p < .001). In ALM patients, older age, male sex, higher comorbidity burden, increased tumor thickness and ulceration, positive lymph nodes, and positive metastasis were independently associated with lower 5-year survival. Multimodality therapy, defined as surgery in addition to systemic therapy and/or radiation therapy, was associated with higher survival in stage III patients but not in other stages. These results call for further investigation into possible treatment intensification in the ALM population in the future.

Subungual Melanoma: A Single Institution Experience

Despite the changing paradigms of melanoma treatment in recent years, there remains a relative paucity of data regarding subungual melanoma in the literature. From 2002–2018, 25 patients with subungual melanoma were surgically treated at our facility. A retrospective chart review was conducted to collect relevant demographic, clinical, pathologic, and outcomes data. The median age at diagnosis was 69 years. Most patients (60%) were male, and the melanoma lesion was most often located on the foot (68%). Acral-lentiginous was the most common histologic subtype (59%), and the median Breslow thickness was 3.4 mm. Fifteen patients (63%) underwent a sentinel lymph node biopsy as part of their surgical resection, and four of these patients (27%) had metastatic disease in the lymph nodes. In total, 10 patients underwent lymph node dissection of the involved basin. The median follow up was 21 months in this patient population. Age, gender, tumor location, ulceration, and lesion histology were not significantly associated with recurrence free survival (RFS). Increasing Breslow thickness was found to be significantly associated with shorter RFS (HR: 1.07, CI: 1.03–1.55). In total, 13 patients developed a disease recurrence, and RFS rates were 66% at 1 year and 40% at 3 years. Additionally, 91 and 37% of patients were alive at one year and three years, respectively. Subungual melanomas are rare lesions that often have a more advanced stage at diagnosis, which contributes to the poor prognosis of these cutaneous malignancies.

Melanoma of the Hands and Feet (With Reconstruction)

Melanomas only account for 4% of all dermatologic cancers yet are responsible for 80% of deaths. Notably, melanomas of the hand and foot have a worse prognosis when compared with melanomas of other anatomic regions. Likely this is due to intrinsic biologic characteristics, delayed diagnosis, difficult surgical excision due to delicate anatomy, and lack of definitive diagnostic and therapeutic guidelines. The most common locations of melanoma of the hand, in order of decreasing frequency, are subungual area, dorsal surface, and palmar surface. The most common locations of melanoma of the foot are the plantar surface, dorsal surface, and subungual area, in decreasing frequency. Diagnosis of melanoma of the hand and foot can be difficult because the traditional "ABCDE" (asymmetric shape, border, color, diameter, evolution) rules do not apply. Newer acronyms have been proposed in literature including "CUBED" (colored, uncertain, bleeding, enlarged, delayed) and "ABC rule for Subungual Melanoma." Once diagnosed, treatment is primarily surgical excision and reconstruction. The goal for the surgeon is to maintain the function and anatomy of the hand or foot.

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.

Tumor invasion in the hyponychium is associated with distant metastasis and poor prognosis in subungual melanoma: A histologic landscape of 44 cases

BACKGROUND

Subungual melanoma (SUM) has a poor prognosis because of delayed diagnosis. Its progression, consensus on surgical treatment, and correlation with clinical outcomes remain unclear.

OBJECTIVE

We aimed to identify the pattern of dermal invasion in different locations of the nail apparatus and its relationship with prognosis.

METHODS

In this retrospective review of surgically treated SUM patients between January 2011 and April 2019, the nail apparatus was divided into 5 anatomic subunits: the dorsal roof of proximal nail fold, ventral floor of proximal nail fold, germinal matrix, nail bed, and hyponychium. Invasions in the subunits were categorized using 3 criteria: no tumor, in situ tumor, or invasion.

RESULTS

Among 44 cases of SUM, dermal invasion occurred mostly in the distal areas, with 11, 30, 18, 7, and 4 in the hyponychium, nail bed, germinal matrix, ventral floor of proximal nail fold, and dorsal roof of proximal nail fold, respectively. The patients with hyponychial invasion showed a significantly greater Breslow depth (P = .009), a higher rate of lymph node metastasis (P = .019), distant metastasis (P = .036), and shorter disease-free survival (P = .001).

CONCLUSION

Hyponychial invasion is an important prognostic predictor of SUM, given its strong association with invasion depth, metastatic progression, and disease-free survival. Patients with invasion in the hyponychium should undergo more strict workup, treatment, and surveillance.

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.

Retrospective analysis of nail biopsies performed using the Medicare Provider Utilization and Payment Database 2012 to 2017

Subungual melanoma (SUM) is subset of acral melanoma that develops within the nail unit and is associated with a poor prognosis. Nail biopsy is the only way to definitively diagnosis SUM. Our objectives were to analyze the Medicare database for nail biopsy utilization and to compare the annual nail biopsy rate with the estimated incidence of SUM in the United States. A retrospective study on nail biopsy data was performed using the Medicare Provider Utilization and Payment Database 2012 to 2017. The number of nail biopsies performed per 100 000 people was compared to SUM incidence per 100 000 people. Podiatrists, dermatologists, other physicians, and NP/PAs respectively performed 12.12, 0.42, 0.08, 0.07 nail biopsies per 100 000 people annually. Dermatologists performed adequate nail biopsies to cover the minimum (0.7%), but not the maximum (3.5%) estimated incidence of SUM. Only 0.28% and 1.01% of general dermatologists and Mohs surgeons, respectively, performed nail biopsies in 19/50 (38.00%) states and 69/929 (7.42%) zip codes. Limitations of our study were that nail biopsies on patients less than 65 years, and those with no or commercial health insurance were not analyzed. In sum, very few dermatologists performed nail biopsies in the Medicare database. Increased efforts are needed to educate dermatologists on nail surgery.

Management of Nail Unit Melanoma

Nail unit melanoma is an uncommon form of melanoma with worse prognosis compared with nonacral cutaneous melanoma. Nail unit melanoma is often diagnosed at a late stage. Clinical and dermoscopic features may suggest a diagnosis of nail unit melanoma, but confirmation requires histologic analysis. Like the clinical diagnosis, histopathologic diagnosis of nail unit melanoma is also difficult. The surgical management of nail unit melanoma has evolved from aggressive amputations to digit-sparing approaches. This article reviews the clinical presentation, diagnosis, and surgical treatment of nail unit melanoma to promote early diagnosis and rational surgery.

Diagnosis of Melanonychia

Melanonychia has many causes and can involve one or several fingernails or toenails, and may occur at any age. Dermoscopy is used routinely in the evaluation of a pigmented nail. If pigmentation is caused by melanin produced by nail matrix, identify whether the pigmentation is caused by an activation or proliferation of nail melanocytes. When melanocytic proliferation is suspected, biopsy with histopathologic examination is the gold standard for diagnosis and is recommended when a longitudinal melanonychia occurs in an adult and is localized in a single digit, in the absence of local or systemic causes that may explain its onset.

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.

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 Rare Case of Osteoinvasive Amelanotic Melanoma of the Nail Unit

Introduction

Amelanotic melanoma is a rare subtype, which may be clinically difficult to diagnose due to lack of pigmentation and variable histopathological features. Osteoinvasion is another rare characteristic of melanoma. There are few reports in the literature of amelanotic melanoma of the nail unit (nail bed, matrix, and nail folds) with invasion of bone.

Case Presentation

We present a case of a 73-year-old Caucasian male with a 13-month history of an ungual lesion on his right hallux. The lesion was initially treated as a chronic diabetic ulceration with failure to resolve with standard of care.

Discussion/Conclusion

A heightened index of suspicion for a malignant process is necessary when standard of care fails to lead to improvement or resolution. In these instances, biopsy should be seriously considered.

Clinical and molecular features of subungual melanomas are site-specific and distinct from acral melanomas

Subungual melanomas (SUM) arise beneath the nails of the hands and feet, and account for 0.7-3.5% of all malignant melanomas. Most studies include SUM in the category of acral melanoma, but understanding the specific features of SUM is critical for improving patient care. In this study, we performed a site-specific comparison of the clinical and molecular features between 54 cases of SUM and 78 cases of nonsubungual acral melanoma. Compared to patients with acral melanoma, patients with SUM were younger at diagnosis, had a higher prevalence of primary melanomas on the hand, and had more frequent reports of previous trauma at the tumor site. SUM was deeper than acral melanoma at diagnosis, which correlated with an increased frequency of metastases. Analysis of common melanoma driver genes revealed KIT and KRAS mutations were predominantly found in SUM, whereas BRAF and NRAS mutations occurred almost exclusively in acral melanoma. We also discovered molecular differences in the cell cycle pathway, where CDK4/CCND1 amplifications were more frequent in SUM and CDKN2A/B loss occurred mostly in acral melanoma, and in the PI3K/mTOR pathway, where RICTOR amplification and TSC1 K587R mutations were exclusively in SUM and PTEN loss and AKT1 mutations were exclusively in acral melanoma. Comparison of hand versus foot tumors revealed more frequent ulceration of SUM foot tumors, which correlated with more distal metastases and poorer overall survival. In summary, we find SUM are both clinically and molecularly distinct from acral melanoma, and our data suggest KIT, CDK4/6, and mTOR inhibitors may be particularly relevant and effective treatments for patients with SUM.

Developing a predictive model for distinguishing invasive nail unit melanoma from nail unit melanoma in situ

BACKGROUND

Clinical information that distinguishes invasive nail unit melanoma from nail unit melanoma in situ before surgery would aid physicians in the decision-making process and estimating prognosis. However, limited information is available on the detailed demographic and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ for differential diagnosis.

OBJECTIVE

This study aimed to investigate the demographic data and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ and establish a predictive model for differentiating these two forms of nail unit melanoma.

METHODS

A retrospective observational study of ninety-seven patients diagnosed with nail unit melanoma (59 in situ and 38 invasive cases) in four healthcare centres in South Korea (three tertiary referral hospitals and one second referral hospital) from March 2014 to December 2019.

RESULTS

A multivariable analysis revealed that ulcer (odds ratio = 21.6, confidence interval = 2.1-219.8, P = 0.009), total melanonychia (odds ratio = 17.6, confidence interval = 3.0-104.0, P = 0.002), nail plate destruction (odds ratio = 10.9, confidence interval = 2.0-59.4, P = 0.006) and polychromia (odds ratio = 5.3, confidence interval = 1.36-20.57, P = 0.016) were distinctive dermoscopic features of invasive nail unit melanoma. A predictive model with scores ranging from 0 to 6 points demonstrated a reliable diagnostic value (C-statistic = 0.902) in differentiating invasive nail unit melanoma from nail unit melanoma in situ.

CONCLUSIONS

Invasive nail unit melanoma and nail unit melanoma in situ have different dermoscopic features. A predictive model based on morphologic dermoscopic features could aid in differentiating invasive nail unit melanoma from nail unit melanoma in situ.

Clinicopathological Features and Prognostic Factors of Primary Acral Melanomas in Caucasians

Background: Cutaneous melanomas located on the acral part of extremities (hand and foot melanoma; HFM) comprise a rare group within all melanomas in Caucasians. HFM is associated with a poor prognosis. We aimed to evaluate clinicopathological features, long-term outcomes, and prognostic factors in primary HFM in Caucasians. Methods: Medical records of all consecutive patients treated between 1997 and 2014 were revised. Patients were diagnosed with primary cutaneous melanoma at I-II clinical stage, and sentinel lymph node biopsy was conducted. The analysis was performed to define the clinicopathological factors influencing outcomes in the HFM and subungual cohort. Among 2537 consecutive patients diagnosed with primary cutaneous melanoma, 247 cases of HFM (9.7%) were found, with a median follow-up time of 7.8 years. Results: Median primary tumor Breslow thickness in subungual melanomas and HFMs was 4.0 mm and 3.3 mm, respectively, significantly higher than in the entire population (median 2.2 mm; p < 0.01). In the HFM group, 37.6% of tumors were ulcerated. Metastases to sentinel lymph node (SLN) were found in 28.3% of HFMs. The 10-year overall survival rate in the HFM group and subungual melanomas was 48.1% and 49.3%, respectively, compared to 63.0% in non-HFM melanomas. Conclusions: Our results confirm that patients with HFMs display worse overall survival compared to the entire melanoma population, with male gender and positive SLN biopsy status acting as independent negative prognostic factors.

Extensive Perineural Spread of Subungual Melanoma

BACKGROUND

Subungual melanoma (SUM) is a rare form of melanoma confined to the nailbed and is rarely of the desmoplastic subtype. The often subtle nature of SUM, initially starting as a small dark spot or line in the nailbed, means deeper invasion can occur before a patient seeks clinical evaluation for a large, ulcerated lesion. We report the only known case of perineural spread of SUM of the lower extremity and describe its extensive path of perineural spread from the toe.

CASE DESCRIPTION

A 72-year-old man with a distant history of SUM status post second ray amputation, presented for evaluation of ipsilateral foot drop. Imaging revealed nodular involvement of tibial, peroneal, and sciatic nerves. Biopsies revealed desmoplastic melanoma and he was treated with nivolumab.

CONCLUSIONS

We report the only known case of perineural spread of SUM of the lower extremity and describe the pathoanatomy of perineural spread. A high index of suspicion for recurrent disease should be maintained even many years after completion of treatment.

Malignant tumours of the foot and ankle

Tumours of the foot and ankle constitute about 4-5% of all musculoskeletal tumours with the majority of them being benign. Diagnosis of malignant soft tissue or bone tumours is frequently delayed because of the relatively low prevalence and uncommon presentation at the foot and ankle. Suspicious lesions or lumps should be subjected to CT, MRI and biopsy. Subfascial location, lump size more than 5 cm, increase in size, painful and recurrent tumours should raise the suspicion of malignancy and lead to patient referral to a designated tumour centre. Neoadjuvant and adjuvant systemic chemotherapy and/or radiation therapy, isolated limb perfusion (ILP) and hyperthermia for malignant tumours have to be discussed in a multidisciplinary tumour board. With the advances in local and free tissue transfer, limb-sparing techniques have increasingly replaced primary amputations thus preserving lower limb function as much as possible without compromising on the principles of oncologic resection.

Melanoma of the nail apparatus: a systematic review and meta-analysis of current challenges and prognosis

Nail apparatus melanoma (NAM) is a rare dermatologic malignancy. Its prognosis is poor because it is often diagnosed late. However, progression and survival of NAM patients have only been studied among small populations. Early biopsy could help to identify suspicious lesions at a less invasive stage. While surgery is generally seen as the treatment of choice, the extent of excision margins and the use of sentinel biopsy remain debated. This systematic review aims to summarize the treatment procedures and observed prognosis in the literature during the last two decades and present pooled survival and progression rates of NAM by using meta-analysis. A systematic review on studies assessing pathology, treatment and prognosis of NAM was carried out up to end of 2018. After evaluation of eligible studies, the main emerging topics were outlined and pooled survival outcomes estimated. A total of 30 articles out of 624 identified records were included for systematic review. Finally, meta-analysis of pooled mortality rates including 18 studies was 4.6 × 100 patient-years (95% CI: 2.7, 6.8) equivalent to 5-year cumulative survival of 77.0%. Additionally, the pooled progression rate based on 17 studies was 6.3 × 100 patient-years (95% CI: 4.1, 8.9) with estimated 5-year cumulative progression-free survival of 68.5%. While the optimal extent of surgical treatment remains debated, prompt biopsy could help to identify early lesions. This is the first study to present pooled survival and progression rates by meta-analysis.

Is the survival rate for acral melanoma actually worse than other cutaneous melanomas?

It is still not clear whether the survival rate for acral melanoma (AM) is better or worse than that of cutaneous melanoma developed at other sites. We sought to evaluate the difference in survival depending on the primary tumor site of cutaneous melanoma. We retrospectively reviewed primary cutaneous melanoma cases diagnosed at Samsung Medical Center, a tertiary institution in Korea, from January 1995 to July 2017. The cohort consisted of 642 patients, with 389 non-acral cutaneous melanoma (NACM) patients and 253 AM patients. The AM patients had a higher percentage of stage 0 diagnoses than the NACM patients (31.6% vs 6.9%, respectively). The factors associated with overall survival were primary tumor site, sex, age, American Joint Committee on Cancer stage, surgery and medical treatment (P < 0.05). Non-acral sites showed worse survival in multivariable analysis (hazard ratio [HR], 1.457; 95% confidence interval [CI], 1.051-2.020; P = 0.0240). Among the NACM, melanomas on the trunk were associated with a higher risk of mortality compared with AM (HR, 1.883; 95% CI, 1.142-3.107; P = 0.0131). Acral melanoma was associated with a better prognosis than non-acral melanoma, specifically when located on the trunk, in Korean patients.

Does sentinel lymph node status have prognostic significance in patients with acral lentiginous melanoma?

BACKGROUND

The prognostic benefit of sentinel lymph node biopsy (SLNB) and factors predictive of survival specifically in patients with acral lentiginous melanoma (ALM) are unknown.

METHODS

The SEER database was queried for ALM cases that underwent SLNB from 1998 to 2013. Clinicopathological factors were correlated with SLN status, overall survival (OS), and melanoma-specific survival (MSS).

RESULTS

Median age for the 753 ALM study patients was 65 years, and 48.2% were male. Median thickness was 2 mm with 38.1% of cases having ulceration. SLN metastases were detected in 194 of 753 cases (25.7%). Multivariable analysis showed that thickness, Clark level IV-V, and ulceration significantly predicted for SLN metastasis (P < 0.05). For patients with positive SLN, 5-year OS and MSS were significantly worse at 48.1% and 58.9%, respectively, compared with 78.7% and 88.5%, respectively, for patients with negative SLN (P < 0.0001). On multivariable analyses, older age, male gender, increasing thickness, ulceration, and a positive SLN significantly predicted for worse OS and MSS (all P < 0.05).

CONCLUSION

This study confirms the important role of SLNB in ALM. SLN metastases are seen in 25.7% of ALM cases, providing significant prognostic information. In addition, thickness, ulceration status, and SLNB status significantly predict survival in patients with ALM.