Neurocutaneous melanosis presenting as chronic partial epilepsy

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.

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.

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.

Amygdalar neuromelanosis intractable epilepsy without leptomeningeal involvement

Neurocutaneous melanosis (NCM) is a rare, congenital neuroectodermal dysplasia generally resulting in early death from neurological decline due to leptomeningeal involvement. Nonmeningeal CNS epileptogenic lesions presenting in later childhood in the absence of leptomeningeal disease are rare. This report summarizes a rare presentation and curative epilepsy surgery. The authors discuss the case of a 14-year-old girl with NCM who originally presented with intractable partial-onset seizures. The MRI, PET, and SPECT studies subsequently revealed a focal epileptogenic source in the right temporal lobe. Results of video-electroencephalography monitoring concurred with the imaging findings, and a right temporal lobectomy was performed including the medial structures. Following surgery, histopathological features of the lesion included multiple scattered mononuclear cells with brown pigmentation in the amygdala specimen. The patient remains seizure free 2 years postresection, and no longer needs medication for seizure management. This patient presented with an atypical CNS manifestation of NCM that is curable by epilepsy surgery. Her intractable epilepsy developed secondary to amygdalar neuromelanosis, which had no associated leptomeningeal melanosis, an uncommon occurrence. As evidenced by the lack of seizure activity following resection, the patient's quality of life greatly improved after neurological surgery.

Fatal leptomeningeal melanoma in neurocutaneous melanosis

We report an unusual occurrence of a primary dural-based malignant melanoma in a 13-year-old boy with neurocutaneous melanosis. The lesion presented with rapid-onset symptoms characterized by raised intracranial pressure and seizures, had an aggressive clinical course, and proved to be fatal despite two surgeries and adjuvant therapy. There should be a high index of suspicion for the occurrence of such a malignant leptomeningeal tumor in patients with congenital melanocytic nevi presenting with neurological symptoms of recent onset.

Neurocutaneous melanosis: surgical pathological features of an apparently hamartomatous lesion in the amygdala

Neurocutaneous melanosis (NCM) is a rare, congenital phakomatosis characterized by the presence of congenital melanocytic nevi and a benign or malignant pigmented cell tumor of the leptomeninges of the CNS. Here the authors report the surgical pathological features of a lesion in the left amygdala in a 10-year-old girl with giant congenital pigmented nevi and mesial temporal lobe epilepsy. The lesion exhibited high intensity on T1-weighted MR images and low intensity to isointensity on T2-weighted images. A left anterior temporal lobectomy and hippocampectomy were performed. Histologically, the lesion was composed of melanin-containing polygonal cells arranged in solid alveolar or multiple lobular patterns. Immunohistochemically, the cells were immunoreactive for HMB45, S100 protein, and vimentin, the profiles being consistent with those of melanocytes. Bundles of astrocytic processes surrounded the nests of melanocytes. Melanin-containing and dysmorphic neurons were also scattered near the nests. In the temporal neocortex adjacent to the amygdaloid melanocytic lesion, cortical dysplasia with cortical laminar disorganization was evident. Based on the histopathological features, the parenchymal lesion appeared to be hamartomatous in nature rather than a neoplasm, involving aberrant migration of melanocytes into the developing neuroepithelial tissue. This case appears to represent an unusual CNS manifestation of NCM.