Subungual melanoma: A retrospective cohort of 157 cases from Brazilian National Cancer Institute

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.

Prevalence of subungual melanoma in patients with cutaneous malignant melanoma: A systematic review and meta-analysis

BACKGROUND

Subungual melanoma (SUM) is a rare type of cutaneous malignant melanoma (CMM) associated with poor prognosis, while data regarding its prevalence are scarce.

OBJECTIVES

We sought to provide a comprehensive systematic review and meta-analysis of the prevalence rates of SUM among all types of CMM, considering certain demographic and clinical characteristics.

METHODS

The MEDLINE electronic database was searched systematically to identify eligible studies providing prevalence rate estimates of SUM in patients with CMM. Included studies were further analysed to estimate the relative prevalences of SUM according to study design, study years, geographical region and sex distribution.

RESULTS

Twenty-eight studies met the inclusion criteria. The overall SUM prevalence was 1.9% (95% CI [1.5%-2.3%]). The prevalence of SUM did not differ significantly between population- and hospital-based studies and remained stable over time. However, it was found to be significantly higher in Asians compared to patients of other geographical regions as well as in studies with more men than women compared to those with female preponderance (p < 0.001).

CONCLUSIONS

In all, the overall SUM prevalence among all subtypes of CMM was estimated at 1.9%, without significant changes over time, and was found to exhibit significant variability between subgroups of different geographical regions.

Clinical features, molecular pathology, and immune microenvironmental characteristics of acral melanoma

Acral melanoma (AM) has unique biology as an aggressive subtype of melanoma. It is a common subtype of melanoma in races with darker skin tones usually diagnosed at a later stage, thereby presenting a worse prognosis compared to cutaneous melanoma. The pathogenesis of acral melanoma differs from cutaneous melanoma, and trauma promotes its development. Compared to cutaneous melanomas, acral melanomas have a significantly lighter mutational burden with more copy number variants. Most acral melanomas are classified as triple wild-type. In contrast to cutaneous melanomas, acral melanomas have a suppressive immune microenvironment. Herein, we reviewed the clinical features, genetic variants, and immune microenvironmental characteristics of limbic melanomas to summarise their unique features.

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.

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.

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.