Neurocutaneous melanosis

Neurocutaneous Melanosis with Meningeal Melanocytosis: A Rare Case of Intracranial Hypertension and Cutaneous Manifestations

A 50-year-old male presented to the emergency room after experiencing sudden right upper limb facial numbness and dysphasia, followed by full recovery. A brain CT scan showed hyperdense lesions within the left hemispheric sulcus, which raised suspicion of spontaneous subarachnoid hemorrhage. A T1-weighted MRI showed multiple tiny leptomeningeal enhancements in the same area, and a digital subtraction angiography showed no signs of vascular abnormality. Cerebrospinal fluid cytology revealed atypical melanin-containing cells with minimal pleomorphism. One month later, the patient developed sixth nerve palsy, which was determined to be due to intracranial hypertension. Multiple giant nevi on the legs, trunk, and scalp were also observed. A skin biopsy showed well-defined and symmetrical proliferation of melanocytic nevus cell nests in the dermis. An open biopsy was performed due to the suspicious leptomeningeal lesions, which surprisingly revealed diffuse and thick black-colored tissue infiltration of the leptomeninges. Pathology confirmed the diagnosis of meningeal melanocytosis. A ventriculoperitoneal shunt was then placed, and the patient's neurological symptoms gradually improved. Based on the presence of multiple giant nevi on the patient's skin and the finding of diffuse meningeal melanocytosis during the open biopsy, the patient was diagnosed with neurocutaneous melanosis. The patient received 6 cycles triweekly of Ipilimumab and Nivolumab 8 months after initial diagnosis. Unfortunately, the disease progressed and the patient passed away 14 months after initial diagnosis.

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.

Melanocytic lesions of the central nervous system: a case series

ABSTRACT Background: Melanocytic lesions of the central nervous system (CNS) are an infrequent, broad and diverse group of entities, both benign and malignant, found in all age groups, with imaging findings ranging from well-circumscribed focal lesions to diffuse leptomeningeal involvement. On MRI, they are usually distinguished by a high signal on T1WI sequences, given the paramagnetic effect of melanin, thus making it difficult to differentiate among them. Objective: To describe the imaging and epidemiological characteristics of a retrospective series of CNS melanocytic lesions. Methods: MR images of 23 patients with CNS melanocytic lesions diagnosed between January 2012 and June 2018 were analyzed. Results: Most patients were female (14/23; 61%), with a median age of 47 years (range: 3 weeks to 72 years). The primary melanocytic lesions accounted for 8/19 cases (42.1%), which included neurocutaneous melanosis, meningeal melanocytomas and primary malignant melanomas. Secondary melanocytic lesions (metastatic) accounted for 10/19 cases (52.6%). There was one case of a tumor with secondary melanization, from a melanocytic neuroectodermal tumor of infancy. There were also four cases of primary ocular melanomas. The most frequent findings were the cerebral location, high T1WI signal and marked contrast-enhancement. Conclusions: The present review describes the wide variety of melanocytic lesions that could affect the CNS, emphasizing the MRI characteristics. Knowledge of the imaging, clinical and epidemiological characteristics of CNS melanocytic lesions is essential for their correct interpretation, given the significant overlap between lesion features and the variable prognosis.

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.

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).

Neurocutaneous Melanosis Presenting as Cavernous Hemangioma Persistent Abdominal Pain

Neurocutaneous melanosis (NCM) is a rare congenital syndrome characterized by the presence of multiple congenital melanocytic nevi and the proliferation of melanocytes in the central nervous system. The authors present a 9-year-old Chinese boy whose clinical manifestations are intermittent headache for 2 months and persistent abdominal pain for 10 days. 3D-reconstruction computed tomography angiography image, digital subtraction angiography, and magnetic resonance imaging plus angiography (MRI+MRA) examinations results suggested that cavernoma at left frontal lobe potentially associated with hemorrhage. In addition, miliary abnormal signals were widely scattered on MRA image so that other malignant metastatic diseases cannot be ruled out. GI physical examination had not any abnormal findings, antispasmodic drugs were ineffective but antiepilepsy drugs were effective to abdominal pain. In surgery, no cavernoma was noticed but an accumulation of densely melanocytic mass located at the lesion on radiology images. The lesions spread along with perivascular of sylvian veins and leptomeningeal. Pathology investigation demonstrated brain metastatic malignant melanoma associated with hemosiderosis. The lesion of brain parenchyma was totally removed but the spread lesions could not be treated with surgery. Adjuvant radiotherapy was performed but failed to control the malignant development, still the patient died in 3 months postinitial operation. The authors conclude that abdominal pain was a manifestation of epilepsy related to the frontal lobe lesion. Neurocutaneous melanosis is a rare disease, brain metastases result in abdominal pain is rare even more, and it is worth the attention of clinicians.

Brazilian guidelines for diagnosis, treatment and follow-up of primary cutaneous melanoma - Part II

The last Brazilian guidelines on melanoma were published in 2002. Development in diagnosis and treatment made updating necessary. The coordinators elaborated ten clinical questions, based on PICO system. A Medline search, according to specific MeSH terms for each of the 10 questions was performed and articles selected were classified from A to D according to level of scientific evidence. Based on the results, recommendations were defined and classified according to scientific strength. The present Guidelines were divided in two parts for editorial and publication reasons. In this second part, the following clinical questions were answered: 1) which patients with primary cutaneous melanoma benefit from sentinel lymph node biopsy? 2) Follow-up with body mapping is indicated for which patients? 3) Is preventive excision of acral nevi beneficious to patients? 4) Is preventive excision of giant congenital nevi beneficious to patients? 5) How should stages 0 and I primary cutaneous melanoma patients be followed?

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.

Neurocutaneous Melanosis in a Woman with Multiple Brain Melanocytomas, Cutaneous Melanocytosis and Oral Involvement

A 34-year-old female was referred to us for a consultation of her dermatological lesions (pigmented lesions present in her oral cavity and on her right shoulder) in May 2007. These lesions had been present since childhood. Recently, the patient had developed seizures and a headache. An MRI of the brain showed the presence of two intracranial masses. The intracranial tumours were surgically removed whereas skin and mucosal lesions were biopsied. Histological findings of brain tumours were consistent with a diagnosis of “melanocytoma” while cutaneous lesions presented “benign dermal melanocytic infiltrations”. Whole brain irradiation was performed. After 3 months a new melanocytic skin lesion appeared on the scalp with histological picture similar to the other cutaneous ones. At the 5-year follow-up examination no recurrence of intracranial tumour or other skin or mucosal lesions were registered. According to the clinical and histological findings, we classify our case as a form of neurocutaneous melanosis in a young adult patient and we present it for the rarity of this syndrome, for the difficulty of the diagnosis, for the potential aggressive behaviour of intracranial lesions that necessitates a constant attentive follow-up and for the unusual feature of new developing skin lesion during the course of the disease.

Stable Neurocutaneous Melanosis in a Ten-Year-Old Boy with Controlled Partial-Complex Seizures

Neurocutaneous melanosis (NCM) is a rare neuroectodermal dysplasia that includes both central nervous system (CNS) and integumentary melanocytic abnormalities. NCM can present with varied clinical and imaging findings, classically presenting with large melanocytic nevi involving the posterior axial trunk region. We describe a case with predominant small non-scalp and non posterior axial-trunk nevi, which nevertheless demonstrated typical CNS imaging findings. Our case clinically presented with epilepsy that was controlled by medical treatment. The patient also demonstrated motor developmental delay, and an otherwise stable course.

Dermal melanocytosis of the scalp associated to intracranial melanoma: malignant blue nevus, neurocutaneous melanosis, or neurocristic cutaneous hamartoma?

Intracranial invasion of cellular blue nevus is extremely rare, and its malignant transformation is even less common. The differential diagnosis includes neurocutaneous melanosis and neurocristic cutaneous hamartoma. A 50-year-old female presented with intracranial melanoma in contiguity with a congenital blue nevus on the scalp. The patient showed a wide pigmented lesion on the scalp that had grown in the last few years over the congenital blue nevus. Magnetic resonance imaging revealed an intracranial tumor lying contiguous to the nevus. Despite aggressive surgery, the tumor relapsed and the patient developed systemic metastases. We report a rare case of cellular blue nevus showing an unexpected aggressive behavior with extensive extra- and intracranial expansion and distant metastases.

An unusual case of congenital melanocytic nevus presenting as neurocutaneous melanoma coexisting with Tuberous Sclerosis complex: A case report

Introduction

Congenital melanocytic nevi are among the several known risk factors for the development of melanoma. Neurocutaneous melanosis is a rare, congenital, non-hereditary disorder characterized by the presence of multiple and/or giant congenital melanocytic nevi. It is a rare condition, with fewer than 200 cases reported in the literature. Its association with tuberous sclerosis complex, a form of the neurocutaneous syndrome, is an unusual finding which, to the best of our knowledge, has not been documented in the English literature so far. Herein we present the first case documenting such an association in a 16-year-old post-pubertal Indian girl.

Case presentation

In this report, we describe the case of a 16-year-old Indian girl who presented to our hospital with swelling on the scalp which had progressed from the hairline to just above the left brow, causing mechanical ptosis. She was born with a black-pigmented triangular patch covered with hair over the scalp which had increased in size over a period of eight years after birth. An X-ray of her skull and ultrasonography revealed soft tissue swelling in the left temporofrontoparietal region. Magnetic resonance imaging of her brain showed the presence of 8.99 cm × 2.26 cm abnormal signal intensity involving the scalp, a few small tubers with cortical dysplasia in the left frontoparietal region with asymmetric dilatation, and the presence of calcified subependymal nodules within the left lateral ventricle. These findings were suggestive of tuberous sclerosis. A histopathological examination of the swelling was suggestive of congenital melanocytic nevi. The patient underwent surgery. Excision of the tumor with primary skin grafting was done, with the graft being taken from the medial aspect of the right thigh.

Conclusion

This case warrants further research to provide concrete evidence of an association of neurocutaneous melanoma with tuberous sclerosis complex. Research should be conducted to prove whether this is an unusual association or a new syndrome. Also, similar cases in other parts of the globe should be documented, as they would provide substantial support for such an association.

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.

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.

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.

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.

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.

Large congenital melanocytic nevi presenting with lissencephaly with an absent corpus callosum

A neonatal case of provisional neurocutaneous melanosis presenting with lissencephaly is reported. Several congenital nevi were observed on the trunk and extremities of the infant, including a giant congenital hairy nevus over the skull. Brain magnetic resonance imaging revealed a marked ventricular dilatation with pachygyria and an absent corpus callosum; however, an injection of gadolinium did not demonstrate any enhanced lesions. Histopathological investigations by a brain biopsy showed a disorganized and anomalous embryonic cerebral architecture, suggesting lissencephaly. The detailed mechanism of this combined pathology is difficult to explain; however, a developmental disturbance was suggested to be present in both the neural crest cells and the neuroepithelial cells, resulting in the development of neurocutaneous melanosis accompanied with lissencephaly.

Progressive brainstem compression in an infant with neurocutaneous melanosis and Dandy-Walker complex following ventriculoperitoneal shunt placement for hydrocephalus. Case report

Neurocutaneous melanosis (NM) coexisting with the Dandy-Walker complex (DWC) is a rare condition, with fewer than 15 cases reported in the literature. The authors present a case of an infant with NM and DWC suffering from progressive brainstem compression following ventriculoperitoneal (VP) shunt placement for hydrocephalus. This 1-year-old boy with congenital melanocytic nevi had met normal developmental milestones until the age of 11 months, when he began regressing in ambulation and language function. Intractable vomiting had developed 1 week later. Magnetic resonance (MR) imaging of the brain revealed DWC with hydrocephalus, and spinal MR images demonstrated a proliferative process within the meninges, consistent with NM. The patient underwent right frontal VP shunt placement resulting in immediate symptom relief, but 3 weeks later became irritable, increasingly lethargic, unable to pull to stand, and unable to tolerate solid food without choking. Due to these symptoms and intractable vomiting, the patient presented to the authors' institution. Brain MR imaging revealed a new-onset diffuse cystic process with anterior and posterior brainstem compression, marked kinking of the cervicomedullary junction, melanocyte pigmentation of the left temporal lobe, diffuse leptomeningeal enhancement, and no evidence of hydrocephalus. Consistent with these imaging findings, the degree of brainstem involvement upon gross visualization predictably deterred resection attempts beyond those necessary for biopsy. Pathological examination revealed diffuse melanocytosis, and the family decided not to pursue aggressive measures postoperatively. This report indicates the potential for rapid intracranial manifestation of diffuse melanocytosis in NM patients. Although the prognosis is poor, early neurosurgical involvement in these patients may provide tissue diagnosis and the potential for decompression if the process is caught early in its course.

Neurocutaneous melanosis associated with Dandy-Walker malformation

Neurocutaneous melanosis is an uncommon congenital disorder consisting of benign or malignant melanocytic tumors of the leptomeninges with large or numerous cutaneous congenital melanocytic nevi. The Dandy-Walker malformation occurs as an enlarged posterior fossa with high insertion of the tentorium, hypoplasia or aplasia of the cerebellar vermis, and cystic dilatation of the fourth ventricle. To our knowledge, the association of these two conditions has been reported only 14 times. In this article, we present a newborn patient with neurocutaneous melanosis associated with Dandy-Walker malformation, which was diagnosed by magnetic resonance imaging.

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

BACKGROUND

There is a dearth of information regarding the occurrence of neurocutaneous melanocytosis (NCM) in a large cohort of persons with large congenital melanocytic nevi (LMCN) or multiple congenital melanocytic nevi (MCMN).

OBJECTIVE

The purpose of this article is to report occurrence of NCM and other complications in 1008 persons having LCMN or MCMN.

METHODS

Evaluation of information obtained from a database of persons with LCMN or MCMN voluntarily submitted by the affected persons to a nevus support group, the Nevus Network.

RESULTS

Of those with truncal LCMN, 6.8% developed significant complications, 4.8% developed symptomatic NCM, and 2.3% died from either benign or malignant NCM or cutaneous melanoma. Of the 4.8% of persons with a truncal nevus who developed symptomatic NCM, 34% died. Of those with head or extremity LCMN, 0.8% developed symptomatic NCM, and, to date, none have died from any cause. Of the small number with MCMN without a giant nevus, 71% developed symptomatic NCM, and 41% died of it.

LIMITATIONS

Attending physician confirmation of submitted information was unavailable.

CONCLUSIONS

LCMN of the trunk were associated with a relatively low occurrence of medical complications and death in our group, considering the large nevomelanocytic burden present. If symptomatic NCM developed in those with truncal nevi, the occurrence of death rose to a third. LCMN of the head or extremity were associated with minimal medical complications and no deaths. In contrast, most of the rare persons (N = 17) with MCMN developed symptomatic NCM, and more than a third died.

Coexisting intracranial meningeal melanocytoma, dermoid tumor, and Dandy–Walker cyst in a patient with neurocutaneous melanosis

✓ Neurocutaneous melanosis (NCM) associated with Dandy–Walker malformation is a very rare congenital neurodysplasia with the same origin. Primary intracranial melanocytic and dermoid tumors are also benign congenital lesions that usually arise from the leptomeninges and are formed by the inclusion of cutaneous ectoderm at the time of neural tube closure. The authors describe a patient with coexisting intracranial meningeal melanocytoma, NCM with Dandy–Walker malformation, and intraventricular dermoid tumor.

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.