Association between Cutaneous Melanoma and Neurofibromatosis Type 1: Analysis of Three Clinical Cases and Review of the Literature

Melanocytic neoplasms in neurofibromatosis type 1: a systematic review

Neurofibromatosis type 1 ( NF1 ) is commonly mutated in melanoma, yet the risk of melanoma in individuals with NF1 is incompletely understood. We performed a systematic review to investigate the risk and characteristics of melanoma and melanocytic nevi in NF1 individuals. PubMed was searched for articles describing NF1 individuals with melanoma, or melanocytic nevi. Those with cutaneous and ocular melanomas were compared to the general population using Surveillance, Epidemiology, and End Results data. Fifty-three articles describing 188 NF1 patients were included (melanoma n  = 82, melanocytic nevi n  = 93, melanocytic nevi, and melanoma n  = 13). Compared to the general population, NF1 patients with cutaneous melanomas had earlier melanoma diagnoses (49.1 vs. 58.6 years, P = 0.012), thicker tumors (3.7 vs. 1.2 mm, P = 0.006), and more frequent disease-specific deaths (27.3% vs. 8.6%, P = 0.005) with shorter survival (12.9 vs. 34.2 months, P = 0.011). Ocular melanomas made up 15.0% of all melanomas in NF1 patients versus 1.5% in the general population ( P < 0.001). In pooling all population-based studies describing melanoma in NF1 populations, NF1 individuals had 2.55 higher odds of having melanoma compared to the general population. A nevus spilus was commonly reported among NF1 individuals with nevi (44.8%, 39/87). Our findings suggest that NF1 individuals may have a higher risk for developing melanomas and tend to have thicker melanomas and worse survival compared to the general population, highlighting the importance of cutaneous and ophthalmologic surveillance in NF1 patients. Our review also supports the association between NF1 and nevus spilus.

Comparison of Cancer Prevalence in Patients With Neurofibromatosis Type 1 at an Academic Cancer Center vs in the General Population From 1985 to 2020

IMPORTANCE

Neurofibromatosis type 1 (NF1) is a complex genetic disorder that is associated with not only neurofibromas, but also an increased susceptibility to other neoplasms.

OBJECTIVE

To evaluate the prevalence of neoplasia and outcomes among patients with NF1.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted among patients with NF1 at a single academic cancer center from 1985 to 2020 with median (range) follow-up of 2.9 years (36 days to 30.5 years). Of 2427 patients evaluated for NF1, 1607 patients who met the National Institutes of Health consensus criteria for NF1 were included. This group was compared with estimates from Surveillance, Epidemiology, and End Results (SEER) Cancer Statistics Review 1975 to 2015 and SEER participants database unless otherwise specified. Data were analyzed from August 2018 to March 2020.

MAIN OUTCOMES AND MEASURES

Disease-specific survival (DSS) was measured from diagnosis date to date of neoplasm-specific death or censorship and calculated using the Kaplan-Meier method. Survival curves were compared using the log-rank test. Deaths from disease were considered a DSS end point; other deaths were considered censored observations. Secondary outcome measures were comparisons of (1) overall survival of patients with NF1 with neurofibroma neoplasms vs those without nonneurofibroma neoplasms, (2) neoplasm prevalence in the NF1 group vs general population estimates, and (3) age at diagnosis in the NF1 group vs general population estimates for the most common neoplasms in the NF1 group.

RESULTS

Among 1607 patients with NF1, the median (range) age at initial visit was 19 years (1 month to 83 years) and 840 (52.3%) were female patients. Among 666 patients who developed other neoplasms in addition to neurofibromas (41.4%), 295 patients (18.4%) developed glioma and 243 patients (15.1%) developed malignant peripheral nerve sheath tumor (MPNST), the most common neoplasms. Patients with NF1, compared with the general population, developed several neoplasms at a younger mean (SD) age (low-grade glioma: 12.98 [11.09] years vs 37.76 [24.53] years; P < .0001; high-grade glioma [HGG]: 27.31 [15.59] years vs 58.42 [19.09] years; P < .0001; MPNST: 33.88 [14.80] years vs 47.06 [20.76] years; P < .0001; breast cancer: 46.61 [9.94] years vs 61.71 [13.85] years; P < .0001). Patients with NF1 developed neoplasms more frequently compared with the general population (odds ratio, 9.5; 95% CI, 8.5-10.5; P < .0001). Among patients with NF1, significantly lower 5-year DSS rates were found among those with undifferentiated pleomorphic sarcoma (1 of 5 patients [20.0%]), HGG (8 of 34 patients [23.1%]), MPNST (72 of 228 patients [31.6%]), ovarian carcinoma (4 of 7 patients [57.1%]), and melanoma (8 of 12 patients [66.7%]) compared with those who had neoplasms classified as other (110 of 119 patients [92.4%]) (all P < .001) .

CONCLUSIONS AND RELEVANCE

This cohort study found that among patients with NF1, those who developed undifferentiated pleomorphic sarcoma, HGG, MPNST, ovarian carcinoma, or melanoma had significantly lower DSS rates compared with those who developed other neoplasms. This study also found that patients with NF1 developed some neoplasms more frequently and at a younger age compared with individuals without NF1. HGGs and MPNST were noteworthy causes of death among patients NF1. This information may be useful for NF1 patient counseling and follow-up.

Melanoma Arising From a Pre-existing Neurofibroma in a Patient With No Prior Diagnosis of Systemic Neurofibromatosis 1 or 2: A Case Report

ABSTRACT

The pathophysiology of melanoma involves malignant transformation of melanocytes. These can arise de novo or result from malignant transformation of a pre-existing nevus. This case report presents a patient with a new pigmented lesion, arising from a pre-existing neurofibroma, on her left scapula and no personal or family history of systemic neurofibromatosis. Biopsy confirmed the lesion to be malignant melanoma and, after excision, postoperative pathology showed a pre-existing neurofibroma. A review of the literature suggests there may be a link between the pathogenesis of neurofibroma and malignant melanoma, because NF1 mutations are observed in both neurofibromatosis and malignant melanoma. We hypothesize that the pre-existing neurofibroma created a proliferative environment that gave rise to the adjacent neoplasm. Further research is required to understand the shared pathway, because this may lead to novel forms of surveillance and treatment.

Challenges in staging and surveillance of patients with neurofibromatosis and cutaneous malignant melanoma

Malignant melanoma is a skin neoplasm with a rising trend of incidence. Positron Emission Tomography in combination with Computed Tomography (PET-CT) imaging is an essential diagnostic tool for both staging and surveillance of melanoma patients; especially in metastatic disease, where prognosis is poor. We report a case of a patient with known Neurofibromatosis type 1 (NF-1) who presented to the Skin Cancer Multidisciplinary meeting with 11 mm Breslow thickness malignant melanoma of the left forearm. His extensive dermal neurofibromatoses proved a diagnostic challenge to the team. There have been published studies linking NF-1 with malignant melanoma. However the incidence and significance of this has yet to be established. We also discuss the use of PET-CT imaging and skin surveillance in the monitoring and staging of this patient.

Exome sequencing identifies recurrent mutations in NF1 and RASopathy genes in sun-exposed melanomas

We report on whole-exome sequencing (WES) of 213 melanomas. Our analysis established NF1, encoding a negative regulator of RAS, as the third most frequently mutated gene in melanoma, after BRAF and NRAS. Inactivating NF1 mutations were present in 46% of melanomas expressing wild-type BRAF and RAS, occurred in older patients and showed a distinct pattern of co-mutation with other RASopathy genes, particularly RASA2. Functional studies showed that NF1 suppression led to increased RAS activation in most, but not all, melanoma cases. In addition, loss of NF1 did not predict sensitivity to MEK or ERK inhibitors. The rebound pathway, as seen by the induction of phosphorylated MEK, occurred in cells both sensitive and resistant to the studied drugs. We conclude that NF1 is a key tumor suppressor lost in melanomas, and that concurrent RASopathy gene mutations may enhance its role in melanomagenesis.

Neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant, multisystem disorder affecting approximately 1 in 3500 people. Significant advances in the understanding of the pathophysiology of NF1 have been made in the last decade. While no medical therapies for NF1 are currently available, trials are ongoing to discover and test medical treatments for the various manifestations of NF1, primarily plexiform neurofibromas, learning disabilities, and optic pathway gliomas. In addition, mutational analysis has become available on a clinical basis and is useful for diagnostic confirmation in individuals who do not fulfill diagnostic criteria or when a prenatal diagnosis is desired. There are several disorders that may share overlapping features with NF1; in 2007, a disorder with cutaneous findings similar to NF1 was described. This paper addresses the dermatologist's role in diagnosis and management of NF1 and describes the variety of cutaneous and extracutaneous findings in NF1 to which the dermatologist may be exposed.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to discuss the indications and limitations of genetic testing in neurofibromatosis type 1, distinguish common and uncommon cutaneous findings, and recognize the dermatologist's role in diagnosis and management.

Fatal malignant melanoma in a child with neurofibromatosis type 1

Neurofibromatosis type 1 is an autosomal dominant disease and is considered one of the most commonly inherited diseases in humans. Malignant melanoma has been reported in up to 5% of patients with neurofibromatosis type 1. We report a young Saudi boy with neurofibromatosis type 1 who developed fatal metastatic malignant melanoma arising from giant melanocytic nevi within speckled lentiginous nevus (SLN).

Indications for excision of nevi and melanoma diagnosed in a pediatric surgical unit

BACKGROUND/PURPOSE

Childhood melanoma is rare but increasing in incidence. Its management relies on early diagnosis. The purpose of this study is to discuss surgical indications of nevi and diagnosis of melanoma in a pediatric surgical unit.

METHODS

Data relative to the patients who underwent removal of nevi in our pediatric surgical unit from 1999 to 2005 were reviewed to identify indications, histology, and melanoma occurrence.

RESULTS

The most frequent indication was atypical nevus. Compound nevus was the most common finding, followed by congenital and Spitz nevi. Melanoma was diagnosed in 3 excised nevi, and in 1 case it occurred as a metastatic disease.

CONCLUSIONS

Our data showed a pattern of indications for surgery similar to that described in the literature, with a high detection rate of melanoma, nonetheless showing that some rare conditions may delay diagnosis.

Pigmented plexiform neurofibroma: Distinction from a large congenital melanocytic nevus

The substantial clinical and histologic overlap between neurotized congenital melanocytic nevi and the subset of plexiform neurofibromas with hyperpigmentation and hypertrichosis of the overlying skin (pigmented neurofibroma) has led to considerable confusion in the literature. A dark-brown, hypertrichotic plaque covered much of the right lower aspect of the trunk of a 1-year-old girl with a diffuse and plexiform neurofibroma in the same area, numerous café-au-lait macules, and intertriginous freckling. The latter findings were diagnostic of neurofibromatosis-1, which was further supported by the presence of unidentified bright objects on magnetic resonance imaging of the brain. Histologic examination of the hyperpigmented plaque revealed melanocytic hyperplasia at the dermoepidermal junction and a proliferation of rounded, pigmented melanocytes dispersed individually and in occasional small nests in the papillary dermis and scattered within underlying neurofibromatous tissue. Immunohistochemical staining with A103 (Melan-A/MART-1) and PNL2 confirmed the melanocytic differentiation of the pigmented cells, whereas glial fibrillary acidic protein and Leu-7 were detected only within plexiform areas and slender neuroid spindle cells. This case draws attention to the pigmented neurofibroma as a distinct clinicopathologic entity resulting from proliferation of melanocytes and neurosustentacular cells in the setting of neurofibromatosis-1.

Multiple malignant melanomas in association with neurofibromatosis type 1

We present a case of multiple primary malignant melanomata occurring over a six year period in a 63-year-old Caucasian man with neurofibromatosis type 1. There is doubt regarding a definite association between these two diseases despite a number of case reports and clear, potential pathological mechanisms. This case not only strengthens support for an association but also highlights the great difficulties that arise in the management of cutaneous melanomata in patients with neurofibromatosis.

Pigment cell-related manifestations in neurofibromatosis type 1: an overview

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder, affecting approximately 1 in 3500 individuals. The most commonly seen tumors in NF1 patients are the (sub)cutaneous neurofibromas. However, individuals with NF1 typically present in childhood with well-defined pigmentary defects, including cafe-au-lait macules (CALMs), intertriginous freckling and iris Lisch nodules. NF1 is considered a neurocristopathy, primarily affecting tissues derived from the neural crest. Since the pigment producing melanocyte originates in the neural crest, the presence of (hyper)pigmentary lesions in the NF1 phenotype because of changes in melanocyte cell growth and differentiation is to be expected. We want to discuss the pigmentary cutaneous manifestations of NF1 represented by CALMs and intertriginous freckles and the pigmentary non-cutaneous manifestations represented by iris Lisch nodules. Several hypotheses have been suggested in explaining the poorly understood etiopathogenesis of CALMs. Whether other pigmentary manifestations might share similar etiopathogenic mechanisms remains obscure. Additional attention will be drawn to a readily seen phenomenon in NF1: hyperpigmentation overlying (plexiform) neurofibromas, which could suggest common etiopathogenetic-environmental cues or mechanisms underlying CALMs and neurofibromas. Finally, we want to address the relationship between malignant melanoma and NF1.

Cutaneous malignant melanoma and neurofibromatosis type 1

Neurofibromatosis 1 (NF1) is a genetically transmitted disease occurring approximately once in 3000 live births and resulting from mutations of the NF1 gene that encodes a protein named neurofibromin, a negative regulator of the ras-dependent pathway. An excess of neoplasia especially tumours of neuroectodermal origin is classically observed. The occurrence of malignant melanoma in patients with NF1 has already been described in scattered clinical reports but little is known as to the characteristics of melanoma arising in NF1 patients. A multicentric retrospective study was conducted on a panel of French referring centres for a period of 13 years to identify patients with both melanoma and NF1. Patients with mucosal or ocular melanoma were excluded. The diagnosis of malignant melanoma was based on specific histology whereas NF1 was identified according to the criteria proposed by the NIH Consensus Conference. All patient fulfilling criteria for both melanoma and NF1 were investigated using a common procedure recording clinical and histological data along with prognostic factors for the two diseases. Eleven patients were identified with both diseases. The clinical pattern of NF1 was quite similar to the classical form of the disease, but some unusual features were present as regards to the melanoma: a sex-ratio of 10 women for one man and an average age lower than expected (median age=33 years) for melanoma occurrence. Among prognostic factors, median thickness was high compared to large series of melanoma in the literature (3.20 versus 1.5 mm). Another neoplasia occurred in three patients. An increase in melanoma incidence in patients with NF1 remains hypothetical but our small series of malignant melanoma arising in NF1 patients displays a large female preponderance, a higher thickness than expected and a frequent association with a second neoplasia. The peculiar female proneness for cancer whatever its localization and the risk of multiple neoplasias have already been reported in NF1 patients and could be true for malignant melanoma as well.