Large or multiple congenital melanocytic nevi: Occurrence of neurocutaneous melanocytosis in 1008 persons

Refinements in the Preexpanded Distant Flap for Giant Melanocytic Nevi of the Upper Extremity in Pediatric Patients

BACKGROUND

Surgical treatment of large and giant congenital melanocytic nevi (GCMN) of the upper extremity is challenging because of limited options for reconstruction. A preexpanded distant flap is considered an important option in upper extremity reconstruction, where the soft tissue available for use is limited. The authors aimed to refine the preexpanded distant flap after excision of the GCMN in the upper extremity.

METHODS

Large (>10 cm) and giant (>20 cm) congenital melanocytic nevi of the upper extremities treated with tissue expansion and distant flaps over 10 years were retrospectively reviewed, and the authors describe in detail the surgical strategies for reconstruction of the upper extremity with a distant flap.

RESULTS

From March of 2010 to February of 2020, 13 patients (mean age, 2.87 years) treated with 17 preextended distant flaps were included. The mean flap dimension was 154.87 cm 2 , ranging from 15 × 5 to 26.5 × 11 cm. All procedures were successfully completed except for one, in which partial flap necrosis occurred. Preconditioning was performed before flap transfer in 5 patients with larger rotation arcs and flap dimensions. The mean duration of postoperative follow-up was 51.85 months. A new reconstructive protocol was proposed that combined the 3 elements, including a distant flap, tissue expander, and preconditioning.

CONCLUSIONS

In the treatment of GCMN in the upper extremities, careful planning and multiple stages are required. For pediatric patients, the preextended distant flap with preconditioning is useful and effective for reconstruction.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Thickness of melanocytes in giant congenital melanocytic nevus for complete surgical excision: clinicopathological evaluation of 117 lesions according to the area and size

BACKGROUND

Giant congenital melanocytic nevi (GCMN) are usually defined as nevi that exceed 20 cm in maximal diameter or 15% of the total body surface area. There have been reports of life-long malignant change risks arising from GCMN, leading to surgical excision of GCMN. This study aims to evaluate the thickness of melanocytes based on clinical factors in order to provide objective information for the complete resection of the lesion.

METHODS

Overall, 75 patients diagnosed with GCMN between 2000 and 2021 were included, and their clinical records were collected retrospectively. 117 pathologic slides obtained during excision were reviewed to measure nevus thickness. Clinical factors were assessed with a generalized estimated equation model for association with nevus thickness.

RESULTS

The thickness of nevus was significantly associated with the location and size. Nevus thickness was more superficial in the distal extremity than in the head and trunk (P = 0.003 [head]; P < 0.001 [trunk]; P = 0.091 [Proximal extremity]). Nevi sized 60 cm or more were significantly deeper than those measuring 20-29.9 cm (P = 0.035). An interaction between size and location existed (P < 0.001). Trunk and distal extremity lesions consistently exhibited uniform thickness regardless of lesion size, whereas head and proximal extremity lesions showed variations in thickness based on lesion size.

CONCLUSION

GCMNs have differences in thickness according to location and size. Therefore, it is necessary to devise an approach optimized for each patient to treat GCMN. In the study, it was emphasized that the thickness of GCMN is correlated with clinical factors, specifically the location and size of the nevus. Consequently, these findings underscore the need for individualized treatment plans for effective surgical intervention.

Updates in the Management of Congenital Melanocytic Nevi

Congenital melanocytic nevi (CMN) carry an increased risk of melanoma and may be disfiguring, and consensus regarding treatment recommendations is lacking. While clinical monitoring is the standard of care, many caregivers are interested in its removal to prevent psychosocial burden or to decrease risk. Although melanoma can occur regardless of CMN removal, there are a variety of treatments that may offer improved cosmesis or local symptom control, including surgical excision, laser therapy, and other superficially destructive techniques. Regardless of the selected management, these patients are monitored for ongoing melanoma risk. An extensive discussion with families regarding the risks and benefits of observation versus active intervention is essential. To facilitate these discussions, we herein summarize current CMN management strategies and considerations.

Incidence of neurocutaneous melanosis in Japanese pediatric patients with congenital melanocytic nevi

Neurocutaneous melanosis (NCM) is a rare, non-hereditary neurocutaneous disorder characterized by excessive melanocytic proliferation in the skin and central nervous system. As no major studies have covered the incidence of NCM among Japanese patients with congenital melanocytic nevi (CMN), we prospectively investigated the incidence of NCM among Japanese patients who underwent initial treatment for CMN. The relationship of CMN and NCM was also investigated. Japanese pediatric patients with CMN under 1 year of age were included between January 2020 and November 2022, and all patients underwent brain MRI to check for NCM in this study. NCM lesions were most frequently seen in the amygdala, followed by the cerebellum, brainstem, and cerebral hemispheres. NCM was diagnosed on brain MRI in 31.6% of the 38 patients with CMN and in 25.0% of patients with no prior examination or treatment. Distribution and size of CMN, number of satellite nevi, rugosity and nodules were strongly associated with the existence of NCM, and these findings may guide a future registry study with a large cohort of CMN patients.

Neurosurgical management of patients with neurocutaneous melanosis: a systematic review

OBJECTIVE

Neurocutaneous melanocytosis (NCM), also referred to as neurocutaneous melanosis, is a rare neurocutaneous disorder characterized by excess melanocytic proliferation in the skin, leptomeninges, and cranial parenchyma. NCM most often presents in pediatric patients within the first 2 years of life and is associated with high mortality due to proliferation of melanocytes in the brain. Prognosis is poor, as patients typically die within 3 years of symptom onset. Due to the rarity of NCM, there are no specific guidelines for management. The aims of this systematic review were to investigate approaches toward diagnosis and examine modern neurosurgical management of NCM.

METHODS

A systematic review was performed using the PubMed database between April and December 2021 to identify relevant articles using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Search criteria were created and checked independently among the authors. Inclusion criteria specified unique studies and case reports of NCM patients in which relevant neurosurgical management was considered and/or applied. Exclusion criteria included studies that did not report associated neurological diagnoses and neuroimaging findings, clinical reports without novel observations, and those unavailable in the English language. All articles that met the study inclusion criteria were included and analyzed.

RESULTS

A total of 26 extracted articles met inclusion criteria and were used for quantitative analysis, yielding a cumulative of 74 patients with NCM. These included 21 case reports, 1 case series, 2 retrospective cohort studies, 1 prospective cohort study, and 1 review. The mean patient age was 16.66 years (range 0.25–67 years), and most were male (76%). Seizures were the most frequently reported symptom (55%, 41/74 cases). Neurological diagnoses associated with NCM included epilepsy (45%, 33/74 cases), hydrocephalus (24%, 18/74 cases), Dandy-Walker malformation (24%, 18/74 cases), and primary CNS melanocytic tumors (23%, 17/74 cases). The most common surgical technique was CSF shunting (43%, 24/56 operations), with tethered cord release (4%, 2/56 operations) being the least frequently performed.

CONCLUSIONS

Current management of NCM includes CSF shunting to reduce intracranial pressure, surgery, chemotherapy, radiotherapy, immunotherapy, and palliative care. Neurosurgical intervention can aid in the diagnosis of NCM through tissue biopsy and resection of lesions with surgical decompression. Further evidence is required to establish the clinical outcomes of this rare entity and to describe the diverse spectrum of intracranial and intraspinal abnormalities present.

Neurological signs, symptoms and MRI abnormalities in patients with congenital melanocytic naevi and evaluation of routine MRI-screening: systematic review and meta-analysis

BACKGROUND

A congenital melanocytic naevus (CMN) is a rare skin condition that can be associated with abnormalities of the central nervous system (CNS). These anomalies can sometimes cause severe complications, and rarely death. Adequate information about aetiology and management is therefore crucial. To identify how to monitor patients with CMN, we aimed to estimate the prevalence of neurological involvement in patients with CMN and to summarize what specific neurological signs and symptoms and MRI abnormalities are reported in the medical literature. In addition, we summarized and evaluated the recommendations regarding MRI-screening reported in the medical literature.

METHODS

This review was registered in PROSPERO and reported according to the MOOSE checklist. A search was conducted in EMBASE (Ovid), PubMed, and the Cochrane Library. We included studies with 10 or more patients with CMN, reporting on neurological signs and symptoms or CNS MRI. Study selection, data extraction and methodological quality assessment were performed by two independent reviewers. A meta-analysis was used to assess the prevalence of neurological signs and symptoms.

RESULTS

Out of 1287 studies, fourteen studies were eligible for inclusion of which eight were included in the meta-analysis. Neurological signs and symptoms prevalence was 7.04% (CI 95% 4.47-10.93%) in the meta-analysis group and 6.26% (95% CI 3.85-10%) in a subgroup of patients with a CMN > 6 cm, evaluated in seven studies. Neurodevelopmental delay and seizures were the most frequently reported signs and symptoms. CNS melanocytosis and hydrocephalus were the most frequently reported MRI abnormalities. It was not possible to estimate the increased risk of neurological involvement in patients with CMN due to low quality of evidence and clinical heterogeneity.

CONCLUSION

Standardization in CMN studies and a multi-centre prospective study are needed to evaluate neurological involvement. Based on current literature, it is not possible to make strong recommendations on routine MRI-screening. For now, every clinical centre should decide on its own policy and weigh the advantages and disadvantages of routine MRI.

Risk of Malignant Transformation Arising From Giant Congenital Melanocytic Nevi: A 20-year Single-center Study

BACKGROUND

Although giant congenital melanocytic nevus (GCMN) is regarded as premalignant, the incidence and risk factors of malignant transformation are controversial.

OBJECTIVE

This study aimed to share the authors' surgical experience with GCMNs and provide data on their demographics, malignant transformation, and prognosis.

METHODS

This single-center, consecutive study included 152 patients with GCMN who visited this center from March 2000 to February 2020. Their medical documentation was reviewed retrospectively, and the nevi were classified according to the size as follows: Group 1, 10 to 19.9 cm (n = 45); Group 2, 20 to 39.9 cm (n = 62); and Group 3, ≥40 cm (n = 45).

RESULTS

Seven malignancies were found (4.6%; 4 melanomas, 2 rhabdomyosarcomas [RMS], and 1 malignant peripheral nerve sheath tumor [MPNST]). The risk increased according to the nevus size (2.2% in Group 1, 3.2% in Group 2, and 8.9% in Group 3) but the difference was not statistically significant (p = .3305).

CONCLUSION

Malignant transformation from GCMN cannot be ignored. It can include transformation into melanoma, RMS, and MPNST. Early surgical resection and regular follow-up should be performed in patients with nevi ≥10 cm.

Transcriptome Analysis of Large to Giant Congenital Melanocytic Nevus Reveals Cell Cycle Arrest and Immune Evasion: Identifying Potential Targets for Treatment

Large to giant congenital melanocytic nevus (lgCMN) is a benign cutaneous tumor that develops during embryogenesis. A large number of lgCMN patients are ineligible for surgical treatment; hence, there is an urgent need to develop pharmacological treatments. Clinically, tumorigenesis and progression essentially halt after birth, resulting in the homeostasis of growth arrest and survival. Numerous studies have employed whole-genome or whole-exome sequencing to clarify the etiology of lgCMN; however, transcriptome sequencing of lgCMN is still lacking. Through comprehensive transcriptome analysis, this study elucidated the ongoing regulation and homeostasis of lgCMN and identified potential targets for treatment. Transcriptome sequencing, identification of differentially expressed genes and hub genes, protein–protein network construction, functional enrichment, pathway analysis, and gene annotations were performed in this study. Immunohistochemistry, real-time quantitative PCR, immunocytofluorescence, and cell cycle assays were employed for further validation. The results revealed several intriguing phenomena in lgCMN, including P16-induced cell cycle arrest, antiapoptotic activity, and immune evasion caused by malfunction of tumor antigen processing. The arrested cell cycle in lgCMN is consistent with its phenotype and rare malignant transformation. Antiapoptotic activity and immune evasion might explain how such heterogeneous cells have avoided elimination. Major histocompatibility complex (MHC) class I-mediated tumor antigen processing was the hub pathway that was significantly downregulated in lgCMN, and ITCH, FBXW7, HECW2, and WWP1 were identified as candidate hub genes. In conclusion, our research provides new perspectives for immunotherapy and targeted therapy.

Addressing Frequently Asked Questions and Dispelling Myths About Melanocytic Nevi in Children

Melanocytic nevi are congenital or acquired benign melanocytic neoplasms. The reason for the appearance of melanocytic nevi is not precisely known. Melanocytic nevi frequently occur in children, constituting a common reason for consultation in pediatric dermatology clinics. In our experience, many parents and caregivers present doubts and fears based more on popular beliefs than on data with valid scientific evidence. This review answers their frequently asked questions, such as the risk of malignancy, the importance of nevi location, the warning signs of malignant transformation, best prevention strategies, and optimal management, based on the most recent scientific evidence available.

Distribution Patterns (7B Rule) and Characteristics of Large Congenital Melanocytic Nevi: A Retrospective Cohort Study in China

Large congenital melanocytic nevus has a high risk of malignancy. However, few studies have summarized its characteristics, treatments, outcomes and malignancy incidence in Chinese patients. This paper reviews a retrospective cohort study evaluating 1,171 patients from Shanghai Ninth People's Hospital between 1 January 1989 and 31 August 2019 using electronic medical records and phone calls to collect clinical and pathological data in which 133 patients were diagnosed with a large congenital melanocytic nevus. Three patients relapsed, and none developed melanoma among the qualified patients. Besides, a new “7B” rule for distribution patterns of large congenital melanocytic nevi was proposed, including bonce, bolero, back, bathing trunk, breast/belly, body extremity, and body. The most common distribution pattern of large congenital melanocytic nevi was bonce, and all blue nevi distributed as bonce. Statistical analysis showed a significant difference (P = 0.0249) in the “7B” patterns between the melanocytic nevus and the neuronevus. In conclusion, the malignancy rate of large congenital melanocytic nevi is much lower in China than in other regions and people of other races. The pathology of large congenital melanocytic nevus may decide its “7B” distribution pattern.

Neurocutaneous melanocytosis (melanosis)

Neurocutaneous melanosis (NCM; MIM # 249400; ORPHA: 2481], first reported by the Bohemian pathologist Rokitansky in 1861, and now more precisely defined as neurocutaneous melanocytosis, is a rare, congenital syndrome characterised by the association of (1) congenital melanocytic nevi (CMN) of the skin with overlying hypertrichosis, presenting as (a) large (LCMN) or giant and/or multiple (MCMN) melanocytic lesions (or both; sometimes associated with smaller "satellite" nevi) or (b) as proliferative melanocytic nodules; and (2) melanocytosis (with infiltration) of the brain parenchyma and/or leptomeninges. CMN of the skin and leptomeningeal/nervous system infiltration are usually benign, more rarely may progress to melanoma or non-malignant melanosis of the brain. Approximately 12% of individuals with LCMN will develop NCM: wide extension and/or dorsal axial distribution of LCMN increases the risk of NCM. The CMN are recognised at birth and are distributed over the skin according to 6 or more patterns (6B patterns) in line with the archetypical patterns of distribution of mosaic skin disorders. Neurological manifestations can appear acutely in infancy, or more frequently later in childhood or adult life, and include signs/symptoms of intracranial hypertension, seizures/epilepsy, cranial nerve palsies, motor/sensory deficits, cognitive/behavioural abnormalities, sleep cycle anomalies, and eventually neurological deterioration. NMC patients may be symptomatic or asymptomatic, with or without evidence of the typical nervous system changes at MRI. Associated brain and spinal cord malformations include the Dandy-Walker malformation (DWM) complex, hemimegalencephaly, cortical dysplasia, arachnoid cysts, Chiari I and II malformations, syringomyelia, meningoceles, occult spinal dysraphism, and CNS lipoma/lipomatosis. There is no systemic involvement, or only rarely. Pathogenically, single postzygotic mutations in the NRAS (neuroblastoma RAS viral oncogene homologue; MIM # 164790; at 1p13.2) proto-oncogene explain the occurrence of single/multiple CMNs and melanocytic and non-melanocytic nervous system lesions in NCM: these disrupt the RAS/ERK/mTOR/PI3K/akt pathways. Diagnostic/surveillance work-ups require physical examination, ophthalmoscopy, brain/spinal cord magnetic resonance imaging (MRI) and angiography (MRA), positron emission tomography (PET), and video-EEG and IQ testing. Treatment strategies include laser therapy, chemical peeling, dermabrasion, and surgical removal/grafting for CMNs and shunt surgery and surgical removal/chemo/radiotherapy for CNS lesions. Biologically targeted therapies tailored (a) BRAF/MEK in NCM mice (MEK162) and GCMN (trametinib); (b) PI3K/mTOR (omipalisib/GSK2126458) in NMC cells; (c) RAS/MEK (vemurafenib and trametinib) in LCMNs cells; or created experimental NMC cells (YP-MEL).

Management of congenital melanocytic nevi in the plastic surgery clinic: Families' expectations and their persistent concern about malignancy

BACKGROUND

Children with congenital melanocytic nevi (CMN) were historically managed with surgical removal to lower the risk of malignant transformation. The evolving literature over the last decade has indicated a significantly lower risk than previously estimated. Indications for excision currently revolve around aesthetic and psychosocial concerns. This study describes and evaluates the perspectives and expectations of patients and families referred to a pediatric plastic surgery clinic on CMN management.

METHOD

A two-part questionnaire was administered before and after an initial clinic appointment to evaluate patient and family concerns of lesion growth, risk of malignancy, treatment expectations, and stigmatization.

RESULTS

Thirty questionnaires were completed for 11 male and 19 female patients, mean age 9.2 years (1-25). Referring doctors (majority dermatologists) were rarely concerned about malignancy (8%), but parents listed it as a top reason for wanting the CMN removed (37%) and the most common expectation for the visit followed by information about surgical options and outcome. Before the clinic, 93% were at least "slightly" worried about CMN growth and 96% about malignancy, whereas 63% and 72%, respectively, after the clinic.

CONCLUSIONS

Families want information about surgical excision and are concerned about malignancy, indicating lingering misinformation or misconception about melanoma risk. For the majority, CMN removal remains at least slightly important, presumably for aesthetic reasons and remaining concern about malignancy. Involved health care professionals should assure reliable and coherent patient information about MM risk, indications for surgery and expected outcome to best support families' decision-making.

Clinical course, treatment modalities, and quality of life in patients with congenital melanocytic nevi - data from the German CMN registry

BACKGROUND

Congenital melanocytic nevi (CMN) are associated with mental stress as well as medical risks for those affected. The German CMN registry was initiated in 2005. Herein, we present results from an interim analysis focusing on disease course, treatment modalities, and quality of life.

PATIENTS AND METHODS

One hundred patients enrolled in the registry between 2005 and 2012 were included in this prospective cohort study, and asked to participate in a follow-up survey. In addition, standardized questionnaires were used to collect data on quality of life (dermatology life quality index, DLQI) and perceived stigmatization (perceived stigmatization questionnaire, PSQ; social comfort questionnaire, SCQ).

RESULTS

Eighty-three percent of patients (or their parents) provided answers to the survey questions (mean patient age: 11.2 years, median: 6 years; mean follow-up: 4.4 years). Overall, four individuals were diagnosed with melanoma, including two pediatric cases with CNS melanoma, one adult with cutaneous melanoma, and one case which later turned out to be a proliferative nodule. Four children were diagnosed with neurocutaneous melanocytosis, three of whom exhibited neurological symptoms. Eighty-eight percent (73/83) of patients underwent surgery. Seventy-eight percent reported no or only minor impact of the CMN on quality of life. In general, perceived stigmatization and impairment of social well-being were also low.

CONCLUSIONS

Our results provide an overview of the situation of CMN patients in Germany, Austria, and Switzerland. Three percent of patients developed melanoma; 4 % showed CNS involvement.

Cutaneous and ocular manifestations of neurocutaneous syndromes

Neurocutaneous syndromes are a heterogeneous group of congenital and hereditary disorders with manifestations in the skin and the nervous system, usually together with ocular features that represent diagnostic clues and potential sources of morbidity. Dermatologists and ophthalmologists often need to work together in identifying and managing patients with these conditions; herein, we focus on classic and under-recognized neurocutaneous syndromes. We begin with autosomal dominant genodermatoses characterized by hamartomas and tumors in the skin, eyes, and central nervous system: neurofibromatosis type 1, tuberous sclerosis complex, and PTEN hamartoma-tumor syndrome. This is followed by a discussion of two mosaic disorders, Sturge-Weber syndrome and neurocutaneous melanocytosis. In addition to providing an update on clinical presentations and evaluation of patients with these conditions, we review recent insights into their pathogenesis, drawing attention to relationships among the diseases on a molecular level and implications regarding treatment. We also highlight the major features of other neurocutaneous syndromes that have ocular findings plus pigmentary, vascular, hyperkeratotic, adnexal, connective tissue, photosensitive, and inflammatory manifestations in the skin.

Case reports of fatal or metastasizing melanoma in children and adolescents: a systematic analysis of the literature

Childhood melanoma (ChM) is rare, with clinical and epidemiologic characteristics that differ from those of adult melanomas. The objective of the current study was to systematically identify and analyze case reports and case series of fatal and metastasizing ChM in the medical literature. ChM case reports with a fatal outcome or metastases were identified using a Medline search and subdivided into ChM developing in the absence of a congenital melanocytic nevus (ChM without CMN) and ChM associated with a CMN (ChM with CMN); 258 cases of ChM without CMN (206 cutaneous, 52 noncutaneous) were identified. In cutaneous ChM without CMN with a fatal outcome (n = 155), the mean age at diagnosis was 13.1 years (median 14 yrs). The mean Breslow index in this group was 8.5 mm for children ages 0 to 10 years and 3.7 mm for children ages 11 to 18 years. In ChM with CMN (n = 178; 112 cutaneous, 66 central nervous system [CNS]), the mean age at diagnosis was 5.8 years for cutaneous melanoma (median 3 yrs) and 5.5 years for CMN-associated CNS melanoma (median 3 yrs). The majority of CMN-associated cutaneous melanomas developed in small and giant CMN (vs medium and large); 53.9% of CNS melanomas developed in patients with multiple medium CMN. This study represents the largest and most complete synopsis of ChM case reports in the medical literature. Our analysis supports the view that cutaneous ChM without CMN (or associated with smaller CMN) differs in several important aspects from ChM associated with large or giant CMN.

Update on melanocytic nevi in children

A new or changing melanocytic nevus in a child or adolescent often leads to concern in parents and physicians. To avoid undue alarm and unnecessary procedures, dermatologists should be aware of the natural history and clinical spectrum of nevi in pediatric patients, as well as findings that are potentially worrisome in this age group. This review provides an update on melanocytic nevi in children, focusing on their dynamic evolution over time, molecular insights into nevogenesis, and phenotypic markers for increased risk of melanoma in adolescence and adulthood. Special considerations for Spitz nevi and nevi located in particular sites (eg, scalp, acral, genital) are highlighted. Current understanding of the risks associated with congenital melanocytic nevi of different sizes and strategies for the management of children with numerous acquired nevi, Spitz nevi, and congenital nevi are also discussed.

Giant congenital melanocytic nevus

Giant congenital melanocytic nevus is usually defined as a melanocytic lesion present at birth that will reach a diameter ≥ 20 cm in adulthood. Its incidence is estimated in <1:20,000 newborns. Despite its rarity, this lesion is important because it may associate with severe complications such as malignant melanoma, affect the central nervous system (neurocutaneous melanosis), and have major psychosocial impact on the patient and his family due to its unsightly appearance. Giant congenital melanocytic nevus generally presents as a brown lesion, with flat or mammilated surface, well-demarcated borders and hypertrichosis. Congenital melanocytic nevus is primarily a clinical diagnosis. However, congenital nevi are histologically distinguished from acquired nevi mainly by their larger size, the spread of the nevus cells to the deep layers of the skin and by their more varied architecture and morphology. Although giant congenital melanocytic nevus is recognized as a risk factor for the development of melanoma, the precise magnitude of this risk is still controversial. The estimated lifetime risk of developing melanoma varies from 5 to 10%. On account of these uncertainties and the size of the lesions, the management of giant congenital melanocytic nevus needs individualization. Treatment may include surgical and non-surgical procedures, psychological intervention and/or clinical follow-up, with special attention to changes in color, texture or on the surface of the lesion. The only absolute indication for surgery in giant congenital melanocytic nevus is the development of a malignant neoplasm on the lesion.

NRAS mutation is the sole recurrent somatic mutation in large congenital melanocytic nevi

Congenital melanocytic nevus (CMN) is a particular melanocytic in utero proliferation characterized by an increased risk of melanoma transformation during infancy or adulthood. NRAS and BRAF mutations have consistently been reported in CMN samples, but until recently results have been contradictory. We therefore studied a series of large and giant CMNs and compared them with small and medium CMNs using Sanger sequencing, pyrosequencing, high-resolution melting analysis, and mutation enrichment by an enhanced version of ice-COLD-PCR. Large-giant CMNs displayed NRAS mutations in 94.7% of cases (18/19). At that point, the role of additional mutations in CMN pathogenesis had to be investigated. We therefore performed exome sequencing on five specimens of large-giant nevi. The results showed that NRAS mutation was the sole recurrent somatic event found in such melanocytic proliferations. The genetic profile of small-medium CMNs was significantly different, with 70% of cases bearing NRAS mutations and 30% showing BRAF mutations. These findings strongly suggest that NRAS mutations are sufficient to drive melanocytic benign proliferations in utero.

Neurocutaneous melanocytosis

Neurocutaneous melanosis or neurocutaneous melanocytosis is a rare sporadic congenital disorder characterized by the presence of giant and/or multiple satellite congenital melanocytic nevi in the skin and benign melanocytic pigmentation of the leptomeninges. These two defining features were recognized more than a century ago. A third characteristic feature is proliferative nodules arising from giant nevi. The etiology is unknown, but neurocutaneous melanosis is considered a developmental disorder of melanocyte precursors from neural crest. The distinctive unique distribution of the congenital giant nevi that gives a "garment" appearance is also an expression of the neural crest. The neurological manifestations often appear in infancy.The special association of neurocutaneous melanosis with Dandy-Walker malformation complex may be explained by a common pathogenesis. Mortality in infancy and childhood is high.

A newborn with neurocutaneous melanocytosis and Dandy-Walker malformation

BACKGROUND

Neurocutaneous melanocytosis is a rare congenital dysplasia of the neuroectodermal melanocyte precursor cells that leads to proliferation of melanin-producing cells in the skin and leptomeninges.

PATIENT

We describe a newborn with a giant congenital melanocytic nevus on his back, buttocks, and thighs. His brain magnetic resonance imaging study revealed bilateral T1 hyperintense lesions in the cerebellum and in the amygdala, hydrocephalus, and a Blake's pouch cyst, consistent with neurocutaneous melanocytosis and Dandy-Walker malformation.

CONCLUSION

Neurocutaneous melanocytosis has a wide clinical spectrum that includes hydrocephalus, epilepsy, cranial nerve palsy, increased intracranial pressure, and sensorimotor deficits.

Making a mountain out of a molehill: NRAS, mosaicism, and large congenital nevi

Linking phenotypic patterns of melanocytic neoplasia to specific gene mutations allows more precise predicting of clinical behavior and response to targeted therapy. In this issue, Kinsler et al. provide evidence that multiple congenital nevi with central nervous system lesions are likely exclusively the result of mosaic mutations in NRAS. We discuss the link between mosaic NRAS mutations, cellular senescence, and clinical phenotype in these nevi.

New recommendations for the categorization of cutaneous features of congenital melanocytic nevi

BACKGROUND

The diameter of congenital melanocytic nevi (CMN) has served as the lone criterion for determining risks of adverse outcomes such as melanoma. A standardized description of additional morphologic features is needed.

OBJECTIVE

We sought to develop a consensus-based standardized categorization of cutaneous features of CMN and to test agreement among experts on the proposed scheme.

METHODS

An interdisciplinary group of experts in the field of CMN was surveyed using a detailed questionnaire. Applicability of the expert consensus-based scheme was tested for interobserver agreement.

RESULTS

The principal variable of the consensus-based categorization is CMN size, based on maximal diameter the CMN is projected to attain by adulthood. CMN size categories include: small (<1.5 cm); medium (M1: 1.5-10 cm, M2: >10-20 cm); large (L1: >20-30 cm, L2: >30-40 cm); and giant (G1: >40-60 cm, G2: >60 cm). In addition, number of satellite nevi in the first year of life is categorized into none, 1 to 20, more than 20 to 50, and more than 50 satellites. Additional descriptors of CMN include anatomic localization, color heterogeneity, surface rugousity and presence of hypertrichosis (described as none, moderate, marked), and presence of dermal or subcutaneous nodules (none, scattered, extensive). Assessment of consistency among 3 experts showed moderate to excellent interobserver agreement for categorization of the clinical descriptors (kappa values 0.54-0.93).

LIMITATIONS

Applicability of the proposed scheme was tested in a virtual setting and only among experts.

CONCLUSION

The proposed categorization scheme for CMN was agreed upon by experts and showed good interobserver agreement. Such standardized reporting of patients with CMN facilitates the development of an international clinical database for the study of large and giant CMN.

[New aspects of congenital melanocytic nevi]

In recent years, prospective studies with increasing patient numbers have been published on the subject of congenital melanocytic nevi (CMN) and neurocutaneous melanocytosis (NCM). Moreover, medical experts and patient support groups have intensified their collaboration. This article summarizes current aspects of pathogenesis, clinical features, and therapy of CMN and NCM.

Neurocutaneous melanosis in association with proliferative skin nodules

We report the case of a 15-year-old boy with giant congenital melanocytic nevi on his back, buttocks, and rear of the two proximal thirds of his thighs, and neurocutaneous melanosis, diagnosed when he was 3 years old. Three melanocytic nodules were present in the giant nevi that were suspected to have malignant degeneration. A biopsy of these nodules was carried out, and histological study revealed benign proliferative melanocytic nodules within the giant congenital melanocytic nevi.

Large congenital melanocytic nevi: associated risks and management considerations

Large congenital melanocytic nevi (LCMN) in neonates can cause considerable concern for parents, family members, and physicians. A detailed understanding of the medical risks, including cutaneous melanoma (CM), extracutaneous melanoma (ECM), and neurocutaneous melanocytosis (NCM), as well as the psychological stress that these lesions can cause in patients, will guide informed management decisions as well as provide comfort to parents. Current data indicate that LCMN greater than 20 cm, and more likely greater than 40 to 60 cm, are the lesions at greatest risk for complications such as CM, ECM, and NCM. Additionally, lesions on the trunk are at greater risk for developing CM, and LCMN in association with numerous satellite nevi are at greatest risk for NCM. Individualized management plans, including clinical observation, magnetic resonance imaging (MRI), and possibly surgery should be based on the risk versus benefit ratio, taking into account the size of the LCMN, its location, the number of satellite nevi, symptoms, and numerous other factors which will be reviewed. This paper will provide a detailed analysis of the risks associated with LCMN, as well as a discussion regarding management and treatment options.

Congenital melanocytic nevi-when to worry and how to treat: Facts and controversies

Congenital melanocytic nevi (CMN) are evident in 1% to 6% of neonates. In some studies, nevi with clinical, dermatoscopic, and histologic features identical to CMN have had a prevalence of more than 15% in older children and adults, possibly reflecting the "tardive" appearance of nevi programmed from birth. There is ongoing debate about the magnitude of the risk of melanoma and other complications associated with CMN of various sizes and the best approach to management of these lesions. We review the natural history of CMN, including proliferative nodules and erosions during infancy, neurotization, and spontaneous regression, and features of variants such as speckled lentiginous and congenital blue nevi. The risk of melanoma arising within small-sized (<1.5 cm) and medium-sized CMN is low (likely <1% over a lifetime) and virtually nonexistent before puberty. Recent data suggest that melanoma (cutaneous or extracutaneous) develops in approximately 5% of patients with a large (>20 cm) CMN, with about half of this risk in the first few years of life. Melanoma and neurocutaneous melanocytosis (NCM) are most likely in patients with CMN that have a final size of >40 cm in diameter, numerous satellite nevi, and a truncal location. One-third of individuals with NCM have multiple medium-sized (but no large) CMN. In patients at risk for NCM, a screening gadolinium-enhanced magnetic resonance imaging, preferably before age 6 months, and longitudinal neurologic assessment are recommended. Management of CMN depends on such factors as the ease of monitoring (more difficult for large, dark, thick nevi) and cosmetic and psychologic benefits of excision or other procedures. CMN require lifelong follow-up. Periodic total body skin examinations are necessary for all patients with large CMN, even when complete resection (often impossible) has been attempted.

Congenital melanocytic naevi

Congenital melanocytic naevi, consisting of clusters of naevo-melanocytes, develop in utero. Although many congenital naevi are visible at birth, some may not become evident until later in life. The timing of naevo-melanocyte proliferation, senescence and melanogenesis may all contribute towards determining when a naevus will become clinically manifest on the skin. Besides the fact that congenital melanocytic naevi may be aesthetically displeasing, resulting in a multitude of psychosocial issues, they also increase the risk for developing cutaneous melanoma, leptomeningeal melanoma, neurocutaneous melanocytosis, malformations of the brain and, rarely, other tumours such as rhabdomyosarcoma and liposarcoma. Whereas the risk of developing malignancy in association with congenital naevi is dependent, to some extent, on the size of the naevus, the risk of developing neurocutaneous melanocytosis correlates best with the number of satellite naevi. Management of patients with congenital melanocytic naevi requires individualization, taking into account the naevus size and location, and the risk of developing cutaneous melanoma or neurocutaneous melanocytosis. When contemplating treatment options, it is important to set realistic expectations and to address the possible aesthetic and functional outcomes, while at the same time addressing the risk for developing cutaneous and/or extracutaneous melanoma.

Large congenital melanocytic nevi and neurocutaneous melanocytosis: one pediatric center's experience

BACKGROUND

Large congenital melanocytic nevi (LCMN) predispose to neurocutaneous melanocytosis (NCM), which is associated with significant morbidity and mortality.

OBJECTIVE

To identify risk factors for NCM in patients with LCMN and suggest guidelines for their management.

METHODS

Medical records of patients with LCMN were reviewed at Sainte-Justine Hospital between 1980 and 2006. Presence of multiple satellite nevi and posterior midline location were evaluated as risk factors for NCM using chi-square test. Magnetic resonance imaging scans were reviewed by a neuroradiologist.

RESULTS

Twenty-six of 52 patients underwent radiologic investigation. Six of 26 (23%) had NCM. Patients with this condition are more likely to have multiple satellite nevi (100% vs 50%, P = .03) and have a trend to posterior midline location of their LCMN (100% vs 60%, P = .08). Patients with NCM are more likely to have both multiple satellite nevi and posterior midline location (100% vs 25%, P = .002). Radiologic findings are also presented.

LIMITATIONS

This was a retrospective case series with imprecise chart data in 38% of cases.

CONCLUSION

The presence of multiple satellite nevi alone or with associated posterior midline location of LCMN is associated with a higher risk of NCM. We recommend magnetic resonance imaging testing before 4 months of age in patients with these features.

Clinical study of the congenital melanocytic naevi in the child and adolescent

BACKGROUND

The classification of the congenital melanocytic nevus (CMN) and the magnitude of the risk of transformation into melanoma are still controversial.

OBJECTIVE

To analyse the profile of the CMN in the child and teenager at IPPMG-UFRJ according to sex, skin colour, age, clinical type, locations and evolution.

METHODS

Longitudinal study of retrospective and prospective cohort from 1994 to 2007. Aleatoric sample from spontaneous or referal demand.

RESULTS

30 children and 30 teenagers showed 74 nevi: 60,8% (small), 27% (medium), 5,4% (large) and 6,7% (giant); from these, 45,9% were in the male sex and 54% in the female sex. There were 45,9% in white and 54% in non-white. Sex and skin colour didn't influence the clinical type. Among the small and medium nevi, 27,1% were located in the trunk, 23% in the head and neck; the large and giant ones in the head,neck, back and limbs; 28,3% were attended for more than 10 years, 47,3% between three and nine years and 24,4% for a time below three years; the small and medium CMN kept unchanged. The fading of the lesion was observed in one large and in two giant CMN. No cases of melanoma were observed.

CONCLUSION

An homogeneous distribution among white/non white and male/female; the sex and the ethnic group did not influence the clinical type; the small CMN was the most frequent clinical type mainly in the trunk.

Giant naevus, giant excision, eleg(i)ant closure? Reconstructive surgery with Integra Artificial Skin to treat giant congenital melanocytic naevi in children

BACKGROUND

The optimal surgical treatment of giant congenital melanocytic naevi remains a considerable challenge in reconstructive surgery. None of the currently available techniques is universally applicable. The goal of this pilot study was to test Integra Artificial Skin (Integra) in the surgical treatment of giant congenital melanocytic naevi.

METHODS

Between May 2000 and March 2004, Integra was used in 12 children (n=12; aged seven months to 11 years, mean 3.8 years). Giant congenital melanocytic naevi covered 1-12% of the total body surface area (mean 4.2%) located over the trunk in 50%, and over face and extremities in 25% each.

RESULTS

In eight children, Integra implantation was primarily successful; in four patients a partial or complete removal and re-implantation was necessary due to complications. The final take rate of Integra ranged from 95-100%, except for one patient with a take rate of 30% (mean 93%). Second stage split-thickness skin grafting yielded take rates from 95-100% (mean 98%). Functional and cosmetic outcome was rated excellent in 58%, good in 25% and fair in 17% (follow-up six months to four years, mean 2.2 years).

CONCLUSIONS

These results suggest that Integra is a new and valid method to successfully treat giant congenital melanocytic naevi in early childhood in a definitive manner and with high-quality results.

The role of surgery in the management of congenital melanocytic naevi in children: a perspective from Great Ormond Street Hospital

Recent advances in research have prompted this review of the role of surgery in the management of congenital melanocytic naevi (CMNs). Good data on the incidence of neurological and malignant complications of CMNs have re-fuelled the debates on whether surgery decreases the risk of malignant melanoma and whether early surgery is advantageous. We conclude the following: 1) untreated CMNs can lighten spontaneously, sometimes dramatically, 2) routine surgery has not been demonstrated to reduce the risk of malignancy and is, therefore, for cosmetic reasons only, 3) early surgery has not been shown to be advantageous and carries increased anaesthetic risk and 4) there is some evidence that surgical intervention may adversely affect the behaviour of the CMN cells. Our current practice is based on the following guidelines: 1) patients are treated in a multidisciplinary-team setting which includes the specialties of paediatric dermatology, plastic surgery and neuroradiology with access to neurology, neurosurgery and oncology, 2) serial photographs are taken at yearly intervals to assess spontaneous lightening. 3) all routine surgery is delayed for at least the first year. 4) patients with facial CMNs (either the principal lesion or large satellites) are offered surgery for cosmetic reasons, 5) patients with a single, easily excisable CMN are offered surgery for cosmetic reasons and 6) all families are made aware of the possibility of spontaneous lightening and the possibility that surgery may have effects on the behaviour of naevus cells.

Large congenital melanotic nevi in an extremity with neurocutaneous melanocytosis

A 14-day-old boy presented with a large congenital melanocytic nevus over his left thigh with approximately 17 satellite nevi distributed over the rest of his skin surface. Six weeks later, he developed generalized tonic-clonic seizures and additional satellite nevi became apparent (n > 20). A subsequent brain magnetic resonance imaging demonstrated right temporal T1 hyperintense signal abnormality. At 4 months of age the patient underwent a lumbar puncture that was normal without evidence of melanocytes or tumor. Nevertheless, a few days later he underwent resection of his right medial temporal lesion which demonstrated melanocytosis in the temporal lobe as well as melanocytosis in subependymal areas in other parts of the brain and ventricles, confirming the suspected diagnosis of neurocutaneous melanocytosis. Our case supports previous studies that conclude that the number of satellite nevi is a greater predictor of neurocutaneous melanocytosis than is the location of large congenital melanocytic nevus. In our case, cerebrospinal fluid studies were not reliable even in the face of florid neurocutaneous melanocytosis involving the leptomeninges and ventricles.