Immunohistochemical detection of the c-met proto-oncogene product in the congenital melanocytic nevus of an infant with neurocutaneous melanosis

Imaging and clinical features of neurocutaneous melanosis in the pediatric population

BACKGROUND

Neurocutaneous melanosis (NCM) is a rare nonfamilial phakomatosis characterized by the presence of congenital melanocytic nevi and abnormal melanocytes infiltration of the leptomeninges.

OBJECTIVE & METHODS

This paper shows the importance of early diagnosis and the most important imaging features of the disease on CT and MR scans. PubMed database was searched from January 1972 to September 2020. Papers including imaging findings of NCM, clinical, follow-up, and treatment features were collected, selecting only 89 studies.

DISCUSSION

NCM is a term used for the first time by van Bogaert in 1948. It refers to a condition caused by an error during morphogenesis and migration leading to leptomeningeal melanocytic accumulation. Although histological findings are the gold standard for diagnosis confirmation, neuroimaging and clinical features strongly support the suspect of NCM. Localization and extension of the lesions are predictive of neurological manifestations related to increased intracranial pressure, mass lesions, or spinal cord compression. CT demonstrates sites of increased density in the anterior temporal lobe - mainly the amygdala - thalami, cerebellum, and frontal lobes base. However, MRI is the best imaging method to diagnose central nervous system lesions, often appearing as T1-short signal areas of the cerebral parenchyma, indicative of central nervous system melanosis. MRI can also reveal associated intracranial and intraspinal abnormalities.

CONCLUSION

Early imaging, when available, is helpful if NCM suspect is raised and may be of guidance in comparing later studies. NCM requires a multidisciplinary approach since it is a multisystem disease with a genetic component.

Clinical Follow-Up of Patients with Neurocutaneous Melanosis in a Tertiary Center; Proposed Modification in Diagnostic Criteria

INTRODUCTION

Neurocutaneous melanosis (NCM) is a rare congenital syndrome. Except for some retrospective studies, information on clinical follow-up and management of these patients are limited. This study aimed to review our experience on diagnostic protocol and clinical follow-up of patients with NCM in a referral children's hospital in Iran.

METHODS

Between 2012 and 2019, eight patients with NCM were consecutively managed in our center. Brain magnetic resonance imaging and cutaneous biopsy were done in all patients at diagnosis. Follow-up surveillance and characteristics of the disease are described.

RESULTS

The mean follow-up period was 25.75 ± 13.81 months, and 75% of patients were male. Most magnetic resonance imaging findings were hypersignal lesions in the temporal lobe (75%), cerebellum (62.5%), brainstem (50%), and thalamus (12.5%). Dandy-Walker syndrome was found in 4 patients (50%), and shunt-dependent hydrocephalus was found in 3 patients (37.5%). Cutaneous malignant melanoma and malignant involvement of the central nervous system were found in 2 (25%) and 3 cases (37.5%), respectively. The mortality rate was 37.5%.

CONCLUSIONS

There are no specific guidelines for management of NCM due to the rarity of the disease. This study proposed modifications in diagnostic criteria, as well as recommendations for follow-up surveillance.

Melanoma arising in a Giant congenital melanocytic nevus: two case reports

Background

A giant congenital melanocytic nevus (GCMN) is found in 0.1% of live-born infants. If present, the lesion has a chance of about 6% to develop into malignant melanoma. Both children and adults can be affected by malignant melanoma arising in a giant congenital nevus. Up to 95% of GCMNs harbor NRAS mutations, and mutations in the BRAF, MC1R, TP53, and GNAQ genes have also been described. The individualization of therapy is required, but diagnostic and prognostic criteria remain controversial.

Case presentations

We report two cases: 1) melanoma arising in a giant congenital nevus during the first month of life complicated with neurocutaneous melanosis (NCM), and 2) melanoma arising in a giant congenital nevus during the first 6 months of life. Pathology, immunohistochemistry, and genetic analyses of tumor tissue were performed. The first case revealed only a non-pathogenic P72R polymorphism of the TP53 gene in the homozygote condition. For the second case, a Q61K mutation was detected in the NRAS gene.

Conclusion

Malignant melanoma associated with GCMN is rare and therefore poorly understood. Outcomes have been linked to the stage at diagnosis, but no additional pathological prognostic factors have been identified. The most frequent genetic event in giant CMNs is NRAS mutations, which was discovered in one of our cases. To accumulate evidence to improve disease prognosis and outcomes, children with congenital melanocytic nevus should be included in a systemic follow-up study from birth.

New insights into neurocutaneous melanosis

BACKGROUND

Neurocutaneous melanosis is a rare disorder in which children with large cutaneous melanotic nevi have associated melanosis in the brain. Although many affected children have structurally normal brains, some have associated developmental disorders or brain anomalies.

OBJECTIVES

To determine the range of extent of brain melanosis as assessed by magnetic resonance imaging (MRI) and to investigate the frequency and types of associated brain anomalies.

MATERIALS AND METHODS

We retrospectively reviewed brain and spine MRIs of 80 patients with congenital melanocytic nevi (range: 1 day to 22 years of age) affiliated with Nevus Outreach Inc. from 1998 to 2017. Central nervous system (CNS) melanosis was diagnosed when a mass with abnormal parenchymal T1 hyperintensity was seen. The locations of abnormal signal, associated malformations, the presence of contrast enhancement and, in patients with more than one MRI, changes over time were recorded. Associations among findings were analyzed using chi-square test or Fisher exact test.

RESULTS

Brain abnormalities were identified in 33 patients. The most common finding was melanosis in the amygdala, which was found in 31 patients (an isolated finding in 14 patients). Nineteen patients had melanosis in the brainstem, cerebellum, cerebral cortex or thalamus. Cerebral and/or spinal leptomeningeal enhancement was uncommon (five patients). Hindbrain melanosis was associated with cerebellar and pontine hypoplasia (P=0.012). Brain melanosis was most easily seen on T1 images prior to myelination; reduced/loss of visibility was noted as the CNS matured.

CONCLUSION

Brain melanosis is a common manifestation in children with large cutaneous melanotic nevi, most commonly found in the anterior temporal lobes (amygdala), brainstem, cerebellum and cerebral cortex. Hindbrain melanosis is associated with hypoplasia of the affected structures. Early imaging is optimal to provide the greatest sensitivity for diagnosis and to guide proper management.

Neurocutaneous melanosis presenting with hydrocephalus and malignant transformation: case-based update

INTRODUCTION

Neurocutaneous melanosis (NCM) is a sporadic condition characterised by congenital melanocytic nevi and melanocytic thickening of the leptomeninges. It is believed to result from congenital dysplasia of melanin-producing cells within the skin and leptomeninges. The management of cutaneous manifestations remains controversial; for neurological manifestations, outcome remains poor even with the use of radiotherapy and chemotherapy.

PATIENTS AND METHODS

We describe the case of a 5-month-old boy who presented with giant congenital melanocytic nevus and hydrocephalus. MR imaging and CSF immunohistochemistry confirmed leptomeningeal melanosis. We discuss the diagnosis, treatment and prognosis of this rare disorder in the light of recent published literature.

RESULTS

Patient required placement of right-sided ventriculoperitoneal shunt to control hydrocephalus. The patient tolerated the procedure well and was discharged home with normal neurological function. A presumptive diagnosis of NCM was made based on the MR characteristics, CSF cytology and clinical presentation. He received trametinib, a MAPK/Erk kinase inhibitor for 7 months. At 30 months of age, he developed left-sided weakness and status epilepticus requiring paediatric intensive care unit admission and ventilator support. The patient eventually succumbed to malignant transformation of leptomeningeal disease.

CONCLUSION

Cutaneous manifestations of NCM are usually congenital, and neurological manifestations develop early in life. Patients with large or multiple congenital nevi should therefore be investigated early to facilitate treatment. MR imaging is the investigation of choice which can further assist in performing biopsy. Symptomatic NCM is refractory to radiotherapy and chemotherapy and has a poor prognosis. A multidisciplinary approach is necessary in the management of NCM patients.

A prospective study of patients with large congenital melanocytic nevi and the risk of melanoma

BACKGROUND:

Large congenital melanocytic nevus (LCMN) is considered a risk factor for melanoma, although the magnitude of this risk is controversial.

OBJECTIVE:

To evaluate the risk of melanoma development in patients with LCMN seen at a dermatology referral center in Brazil during a twelve-year period. To the best of our knowledge, there are no published similar studies on large congenital melanocytic nevus in South America.

METHODS:

Our prospective cohort included only patients with congenital nevi ≥20cm. The cumulative risk of developing melanoma and the standardized morbidity ratio were calculated for patients followed up prospectively for at least 1 month.

RESULTS:

Sixty-three patients were enrolled in this study. One patient who developed melanoma prior to enrollment was excluded, and five were eliminated because of insufficient follow-up time. Mean follow-up for the remaining 57 patients was 5.5 years (median 5.2 years). Median age of entry into the study was 2.6 years. Most patients (75.4%) underwent only clinical observation. Melanomas occurred in 2 (3.5%) patients. Five-year cumulative risk for melanoma was 4.8% (95% CI: 1.9-11.5%). Standardized morbidity ratio was 1584 (95% CI: 266-5232, p<0.001).

STUDY LIMITATIONS:

The small sample size reduces the accuracy of risk estimates.

CONCLUSIONS:

This study analyzed prospectively for the first time data from South America demonstrating that patients with LCMN have a higher risk of developing melanoma than the general population (p<0.001).

Giant congenital melanocytic nevi: selected aspects of diagnostics and treatment

Background

Treatment of giant melanocytic nevi (GMN) remains a multidisciplinary challenge. We present analysis of diagnostics, treatment, and follow-up in children with GMN to establish obligatory procedures in these patients.

Material/Methods

In 24 children with GMN, we analyzed: localization, main nevus diameter, satellite nevi, brain MRI, catecholamines concentrations in 24-h urine collection, surgery stages number, and histological examinations. The t test was used to compare catecholamines concentrations in patient subgroups.

Results

Nine children had “bathing trunk” nevus, 7 had main nevus on the back, 6 on head/neck, and 2 on neck/shoulder and neck/thorax. Brain MRI revealed neurocutaneous melanosis (NCM) in 7/24 children (29.2%), symptomatic in 1. Among urine catecholamines levels from 20 patients (33 samples), dopamine concentration was elevated in 28/33, noradrenaline in 15, adrenaline in 11, and vanillylmandelic acid in 4. In 6 NCM children, all catecholamines concentrations were higher than in patients without NCM (statistically insignificant). In all patients, histological examination of excised nevi revealed compound nevus, with neurofibromatic component in 15 and melanoma in 2. They remain without recurrence/metastases at 8- and 3-year-follow-up. There were 4/7 NCM patients with more than 1 follow-up MRI; in 1 a new melanin deposit was found and in 3 there was no progression.

Conclusions

Early excision with histological examination speeds the diagnosis of melanoma. Brain MRI is necessary to confirm/rule-out NCM. High urine dopamine concentration in GMN children, especially with NCM, is an unpublished finding that can indicate patients with more serious neurological disease. Treatment of GMN children should be tailored individually for each case with respect to all medical/psychological aspects.

Oncogenic codon 13 NRAS mutation in a primary mesenchymal brain neoplasm and nevus of a child with neurocutaneous melanosis

A 28-month female with a clinical diagnosis of neurocutaneous melanosis and numerous intracranial abnormalities (including a right choroid plexus tumor and left hemimegalencephaly) presented with a rapidly expanding tumor in the left occipital cerebrum. Microscopic examination of the resected specimen revealed a myxoid mesenchymal neoplasm consisting of fusiform cells that were immunoreactive for vimentin, CD34, and P53 but no melanocyte markers. Focused amplicon deep sequencing on DNA extracted from the brain tumor and a cutaneous nevus revealed a heterozygous (c.37G > C; p.G13R) substitution in the NRAS gene. DNA sequencing of “normal” skin and buccal swab showed the identical NRAS change albeit at lower allelic frequency. Her parents did not harbor the NRAS mutation. The skin lesion, but not the brain tumor, had a BRAF mutation (c.1397G > T; p.G466V). A germline single nucleotide polymorphism in MET was found in the child and her father (c.3209C > T; p.T1010I). The findings suggest NRAS mosaicism that occurred sometime after conception and imply an oncogenic role of the activating NRAS mutation in both the brain and skin lesions in this child.

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.

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.

Congenital melanocytic nevi: where are we now? Part I. Clinical presentation, epidemiology, pathogenesis, histology, malignant transformation, and neurocutaneous melanosis

Congenital melanocytic nevi (CMN) are present at birth or arise during the first few weeks of life. They are quite common, may have a heritable component, and can present with marked differences in size, shape, color, and location. Histologic and dermatoscopic findings may help suggest the diagnosis, but they are not entirely specific. CMN are categorized based on size, and larger lesions can have a significant psychosocial impact and other complications. They are associated with a variety of dermatologic lesions, ranging from benign to malignant. The risk of malignant transformation varies, with larger CMN carrying a significantly higher risk of malignant melanoma (MM), although with an absolute risk that is lower than is commonly believed. They may also be associated with neuromelanosis, which may be of greater concern than cutaneous MM. The information presented herein aims to help dermatologists determine when it is prudent to obtain a biopsy specimen or excise these lesions, to obtain radiographic imaging, and to involve other specialists (eg, psychiatrists and neurologists) in the patient's care.

Congenital melanocytic nevi

The relative risk for melanoma arising within a congenital nevus is related to the size of the lesion. The timing of and clinical presentation of development of melanoma is also related to the size of the lesion. Medical decisions are individualized taking into account the perceived risk of malignancy, psychosocial impact, and anticipated treatment outcome. In this article, the common features of congenital nevi are discussed as well as the potential individual variations and their impact on treatment recommendations.

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.

Giant congenital melanocytic nevi

BACKGROUND

: Giant congenital melanocytic nevi are rare lesions with the potential to regress into malignant melanoma and/or neurocutaneous melanosis. Appropriate investigations include a screening magnetic resonance imaging scan, neurologic evaluation, and serial clinical observations looking for the development of these complications. Numerous excisional and nonexcisional options have been described for the management of giant congenital melanocytic nevi.

METHODS

: A MEDLINE search was performed to obtain all relevant citations.

CONCLUSIONS

: To successfully treat these complex lesions, the plastic surgeon must understand the disease process, the natural history and complications, and the options for treatment.

Giant congenital melanocytic nevi in neonates: report of two cases

Giant congenital melanocytic nevi are rare, with an estimated incidence of approximately 1 in 20,000 live births. They increase the lifetime risk for malignant melanoma and neurological deficits, including leptomeningeal melanocytosis and epilepsy. Recently, we encountered two patients in whom giant congenital melanocytic nevi were noted at birth. Case 1 presented with the largest nevus spreading across the posterior scalp, neck, chest wall, shoulder and upper back. At the age of 2 months, magnetic resonance imaging (MRI) was performed and no leptomeningeal melanocytosis was found. Case 2 presented with a huge nevus covering most parts of the lower abdomen, lower back, buttocks and bilateral upper thighs. She also had normal MRI findings in the newborn period. At the age of 7 years, leptomeningeal thickening on the surface of the junction between the pons and midbrain was found on brain MRI although she was neurologically asymptomatic. Here, we describe these two cases with congenital melanocytic nevi and review the literature about its clinical manifestations, outcomes, risks for malignant melanoma and neurocutaneous melanosis, and possible surgical interventions.

Neurocutaneous melanosis and the Dandy-Walker complex: an uncommon but not so insignificant association

BACKGROUND

Neurocutaneous melanosis represents a rare congenital but nonheritable phakomatosis defined as the association of giant or multiple congenital nonmalignant melanocytic nevi with leptomeningeal melanosis or melanoma of the central nervous system.

METHODS

We describe the case of an adolescent with a giant congenital bathing trunk melanocytic nevus who developed progressive intracranial hypertension due to leptomeningeal melanosis confirmed by surgical biopsy. Brain and spine magnetic resonance images showed posterior fossa malformation compatible with the Dandy-Walker complex, hydrocephalus, and extensive enhancement of posterior fossa then spine. Shunt placement, corticotherapy, and chemotherapy were attempted leading to transient relief but the boy died 12 months after the onset of primary neurological symptoms.

DISCUSSION

We discuss diagnosis, pathogenesis, management, and prognosis in the light of data from the recent literature.

CONCLUSION

Neurocutaneous melanosis is considered to follow from neurulation disorders which could account for associated developmental malformations as the so-called Dandy-Walker complex. Cutaneous lesions are usually recognized at birth whereas neurological manifestations develop later. Numerous neurological symptoms have been reported according to extent of leptomeningeal and parenchymal infiltration. Whether magnetic resonance imaging of the neuroaxis represents the choice radiological exam, definite diagnosis relies upon the histological data obtained by mean of biopsy. Once symptomatic, surgical and medical measures remain palliative since death occurs within 3 years.

Pigmented lesions of the central nervous system: radiologic-pathologic correlation

Pigmented lesions of the central nervous system (CNS) are a diverse group of entities that run the gamut from benign to malignant. These lesions may be well circumscribed or diffuse, and their imaging appearances are influenced by the degree of melanin content as well as the presence or absence of hemorrhage. Pigmented lesions include primary melanocytic lesions of the CNS and metastatic melanoma, as well as other CNS neoplasms that may undergo melanization, including schwannoma, medulloblastoma, and some gliomas. Primary melanocytic lesions of the CNS arise from melanocytes located within the leptomeninges, and this group includes diffuse melanocytosis and meningeal melanomatosis (seen in neurocutaneous melanosis), melanocytoma, and malignant melanoma. Primary melanin-containing lesions of the CNS must be differentiated from metastatic melanoma because these lesions require different patient workup and therapy. Absence of a known primary malignant melanoma helps in the differential diagnosis, but an occult primary lesion outside the CNS must be sought and excluded. Pigmented lesions of the CNS are uncommon, and knowledge of their imaging characteristics and pathologic features is essential for their identification.

Familial clustering of giant congenital melanocytic nevi

Giant congenital melanocytic nevus (GCMN) is an infrequently occurring congenital malformation. GCMN generally occurs in isolation but rare familial occurrence points to a genetic background. We present two cases of familial GCMN: one with two affected siblings and another with two affected double second cousins. Familial occurrence of GCMN reported in literature is reviewed and an overview of the embryology and proliferation given, illustrating the plethora of factors that might lead to GCMN formation. The pattern of inheritance is likely not Mendelian and discordance in identical twins and the segmental distribution of lesions suggest a post-zygotic mutation. A polygenic paradominant inheritance best explains the clinically observed transmission pattern. Candidate genes include those influencing neural crest development and melanocyte proliferation.

Neurocutaneous melanosis: report of three cases and up-to-date review

Neurocutaneous melanosis is a rare noninherited embryonic neuroectodermal dysplasia, which is observed sporadically and never affects the entire integument. The hallmark of neurocutaneous melanosis in the neonatal period is the presence of a large bilateral hairy dark nevus with satellite nevi over the trunk and neck. The diagnosis should be considered in neonates with large pigmented nevi and in those with more than 3 hairy dark nevi regardless of their size. Neonates with neurocutaneous melanosis are at risk of developing neurological problems. The most common neurological complications are hydrocephalus, seizures, cranial nerve dysfunction, and signs of spinal cord and root involvement. The authors report 3 cases of histologically confirmed neurocutaneous melanosis and describe the course of neurological symptoms and clinical findings including cognitive tests and neuroimaging. The case reports are complemented by an up-to date review on this clinical entity.

Simultaneous occurrence of infantile hemangioma and congenital melanocytic nevus: Coincidence or real association?

Both infantile hemangiomas (IH) and congenital melanocytic nevi (CMN) are common birthmarks that affect approximately 4% to 5% of infants and 1% of newborns, respectively. No previous association has been established between these birthmarks. We report a series of 6 patients who were remarkable for either the proximity or extent of anatomic involvement of their IH and CMN. Patient 1 had a large CMN in the area of her left eye and upper face in addition to a parotid IH. Likewise, patient 5 had a giant CMN on her back and a beard distribution IH. Patients 2, 3, and 4 were found to have small CMNs and localized IH in close anatomic proximity. Patient 6 was seen for a large left parietal scalp CMN with satellite nevi and multiple cutaneous hemangiomas. Although IH and CMN are common birthmarks, the clinical characteristics in these cases suggest a real, not coincidental association. Possible pathogenetic mechanisms to explain this association are discussed.

Giant congenital melanocytic nevi

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Define what is meant by a giant congenital melanocytic nevus and understand its histologic properties. 2. Know the natural history and potential complications associated with a giant congenital melanocytic nevus. 3. Outline the nonsurgical and surgical options available to treat a giant congenital melanocytic nevus.

BACKGROUND

Giant congenital melanocytic nevi are rare lesions with a propensity to degenerate to malignant melanoma. Certain lesions also may be associated with neurocutaneous melanosis, which can on occasion be symptomatic. Appropriate investigations include a screening magnetic resonance imaging scan, neurologic evaluation, and serial clinical observations for the development of cutaneous melanoma. A variety of nonsurgical and surgical options are possible for the treatment of giant congenital melanocytic nevi.

METHODS

A MEDLINE search was performed to gather all pertinent articles from 1955 to 2005.

RESULTS

Giant congenital melanocytic nevi are a difficult diagnostic and reconstructive challenge, requiring careful preoperative evaluation, staged surgical excision, and lifelong patient monitoring and follow-up. With proper treatment, patients can expect a decreased risk of melanoma, with the possibility for early detection and cure of melanoma, amelioration of symptoms, improved aesthetics and psychosocial sequelae, and maintenance of function.

CONCLUSION

The plastic surgeon treating these challenging lesions must have a solid working knowledge of the disease's histology, its natural history and complications, and the options for treatment.

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.

Distinct phenotypic changes between the superficial and deep component of giant congenital melanocytic naevi: a rationale for curettage

BACKGROUND

Giant congenital melanocytic naevi (GCMN) convey a 14-fold increased melanoma risk. In contrast, medium congenital melanocytic naevi (MCMN) are rarely associated with malignant transformation. Management of patients with GCMN is challenging and there is no consensus on the most appropriate strategy for treating these patients.

OBJECTIVES

To provide a rationale for performing curettage of GCMN in the neonatal period in order to reduce the risk of malignant transformation to melanoma.

METHODS

Twenty-six infants with GCMN who underwent biopsies before excisional surgery (n = 7) or curettage (n = 19) during the past 14 years (Academic Hospital, Vrije Universiteit Brussel) and 10 MCMN patients who underwent excision biopsies (Radboud University Nijmegen Medical Centre) were included in this study. Using these biopsies, we performed genetic and detailed immunohistochemical evaluations of changes that are associated with malignant transformation. Variables of interest included melanoma-associated BRAF mutations, proliferative activity, vascularity, cellular context and extracellular matrix architecture.

RESULTS

GCMN and MCMN did not show oncogenic BRAF mutation and displayed similar features with respect to the amount of nonmelanocytic cells within the naevus and matrix architecture. Naevus cells in the superficial component of the GCMN, however, were more proliferative, and this component was more vascular compared with its deep component and with MCMN. In this study, none of the 19 newborn patients who underwent curettage developed a melanoma within a mean follow-up time of 7 years.

CONCLUSIONS

The data presented here support the idea that curettage of GCMN in neonates has the potential for lowering the risk of developing cutaneous melanoma by not only obtaining an important numerical reduction of naevus cells but also removing the 'active' melanocytes.

Asymptomatic neurocutaneous melanocytosis in patients with large congenital melanocytic nevi: A study of cases from an Internet-based registry

BACKGROUND

Recent retrospective studies using magnetic resonance imaging (MRI) to screen for neurocutaneous melanocytosis (NCM) among neurologically asymptomatic children with large congenital melanocytic nevi (LCMN) report high prevalence (23-30%) of asymptomatic NCM. We sought to determine prevalence of asymptomatic NCM, and current application of MRI as a screening tool.

METHODS

Patients with LCMN from an Internet-based registry answered a questionnaire regarding NCM status.

RESULTS

Of 379 patients with LCMN, 26 reportedly had NCM, with 17 reporting neurologic symptoms. Of 186 patients undergoing MRI, 9 reported abnormal findings without neurologic symptoms (4.8%); 80% had LCMN on the posterior axis, whereas 55% had more than 20 satellite nevi.

LIMITATIONS

Study data rely on the registry members' self-reported findings and are limited by lack of independent data verification.

CONCLUSION

Asymptomatic NCM (determined by MRI) may not be common, with much lower prevalence (4.8%) than previously reported. MRI is widely used for screening patients at risk for NCM, such as patients with LCMN involving the posterior axis and greater than 20 satellite nevi.

Giant congenital melanocytic nevi of the trunk and an algorithm for treatment

Giant congenital melanocytic nevi (CMN) are rare, congenital, disfiguring lesions with a risk of degeneration to malignant melanoma. Giant CMN are associated with an increased risk of malignant degeneration. In a minority of cases, patients with giant CMN may have associated neurocutaneous melanosis with leptomeningeal involvement. Giant CMN of the trunk pose difficult diagnostic and reconstructive problems requiring complex multistage treatment. For high-risk cases, diagnostic evaluation in the form of neuro-imaging is an essential component of the planning phase. Although nonsurgical options for the treatment of giant CMN have been advocated, these modalities may decrease the burden of nevus cells but do not result in complete removal of these cells. The ability to monitor nevus cells that remain after nonsurgical management of giant CMN remains questionable. These nonsurgical options include dermabrasion, laser ablation, and chemical peel. In contrast, direct excision of the nevus is the mainstay of treatment of nonsurgical management of giant CMN. There are numerous surgical options to resurface the resultant cutaneous defect after excision of the nevus. The simplest of these options consists of serial excision and direct closure of the defect in stages. However, if the defect cannot be closed by direct cutaneous advancement, other options for wound resurfacing include split- or full-thickness skin graft, tissue expansion, and free tissue transfer. Tissue expansion should be viewed as a category of treatment options because expanders can be used to create an expanded full-thickness skin graft, local expanded flaps adjacent to the lesion, or expansion of a free tissue donor site. Given the diversity of reconstructive options that use tissue expansion, these techniques have evolved as the primary treatment method for giant CMN of the trunk. The authors outline an approach to the evaluation of giant CMN of the trunk, review the risks of melanoma and of neurocutaneous melanosis, describe their preferred treatment regimen, and offer a treatment algorithm for giant CMN of the trunk.

Neurocutaneous melanosis

Neurocutaneous melanosis (NCM) is a rare congenital disorder characterized by the presence of large or multiple congenital melanocytic nevi in association with benign or malignant proliferation of melanocytes in the leptomeninges. NCM is believed to occur as a consequence of an error in morphogenesis in neural ectoderm in the developing embryo. Animal models suggest that aberrant expression of the hepatocyte growth factor/scatter factor (HGF/SF) may be involved in the pathogenesis in the NCM. While the majority of patients with NCM have large congenital melanocytic nevi in a posterior axial distribution, a significant proportion of patients present with multiple smaller nevi in the absence of a single larger lesion. Neurologic manifestations generally occur within the first two years of life, and are often related to increased intracranial pressure. Associated structural anomalies of the CNS have been reported in NCM, particularly the Dandy-Walker complex. The long-term clinical significance of characteristic magnetic resonance findings in neurologically asymptomatic patients is unclear. Approximately half of NCM patients develop CNS melanoma. The prognosis of symptomatic patients remains poor.

The rare phakomatoses

This article outlines the clinical, central nervous system, and neuropathologic features,pathogenesis, genetics, molecular biology, and neuroimaging characteristics of the rare vascular phakomatoses, melanophakomatoses, and organoid phakomatoses.

Congenital melanocytic nevi. Evaluation and management

This article discusses the care of patients with CMN, who often require a multidisciplinary approach involving pediatricians, family physicians, internists, dermatologists, psychologists, plastic surgeons, neurologists, and radiologists. The cosmetic and psychosocial issues, combined with the knowledge of the increased risk of developing melanoma or NCM, is a huge burden that many of these patients and their families have to carry. This article describes the importance for physicians to help these patients and families come to terms with these issues, as well as remind their patients and their family members that although melanoma, NCM, or other complications can develop, most affected individuals do not develop any complications. The article mentions that there are many healthy, happy, functional adults with large, small, and multiple CMN alive today.

Congenital nevocytic nevi: follow-up of a Swedish birth register sample regarding etiologic factors, discomfort, and removal rate

Congenital nevi both small and large are frequently removed. We attempted to study the removal rate and etiologic aspects of congenital nevi as well as their psychosocial effects through the use of a quality test. A questionnaire sent to a sample population of individuals with congenital nevocytic nevi (n=192) collected from the Swedish Medical Birth Register (SMBR) was used as a test of the register's quality and for collecting information on rate of removal and etiologic factors. The quality test indicated that only 85.3% of the nevi listed in the SMBR were true congenital nevocytic nevi. Of all true congenital nevocytic nevi reported in the questionnaire, 39.8% had been removed and none of the rest had developed malignant melanoma. The median time for follow-up was 14 years. The median age at removal of the nevi was 9.7 years. Eight percent of respondents believed that the skin lesion caused taunting and changed their social activities. No infection or illness during pregnancy was specifically related to the development of congenital nevi. In conclusion, the larger the nevi, the more frequently and earlier they are excised. With an excision rate of 40% of congenital nevocytic nevi, we found no malignant melanoma.