Neurocutaneous melanosis with hydrocephalus and syringomyelia. Case report

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 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.

Primary melanocytic neoplasms of the central nervous system

Primary melanocytic neoplasms of the central nervous system (CNS) are rare lesions arising from melanocytes of the leptomeninges. They include diffuse leptomeningeal melanocytosis or melanomatosis, melanocytoma and primary malignant melanoma. We have reviewed the English literature regarding these lesions, which consists of case reports and a small number of larger case series. The presenting features, radiological, surgical and histological findings are reviewed, as are current management options and prognosis. We also present illustrative case reports of diffuse leptomeningeal melanocytosis and primary melanoma of the CNS.

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.

Neurocutaneous melanosis associated with Hirschsprung's disease in a male neonate

Hirschsprung's disease is an inherited disorder characterized by the absence of ganglion cells in the distal bowel. Neurocutaneous melanosis is a rare congenital syndrome characterized by proliferation of melanin-producing cells in the skin and leptomeninges. The authors described a newborn patient with neurocutaneous melanosis associated with Hirschsprung's disease. This male baby had congenital hydrocephalus, large and multiple pigmented skin nevi, and severe abdominal distension. He showed marked hydrocephalus at birth and underwent a ventriculo-peritoneal shunt at the age of 5 days. Investigations for gut motility disorders revealed typical findings consistent with Hirschsprung's disease involving the rectosigmoid colon. He was surgically treated for Hirschsprung's disease after transanal endorectal pull-through at the age of 7 months. After settlement of the ventriculo-peritoneal shunt, the transanal approach was of significant value for keeping the intraperitoneal catheter clean. The association of developmental disorders of melanocytes and enteric ganglia, both of which originated from the neural crest, suggested the presence of mutual pathogenetic factors in the patient.

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.

Meningeal melanocytoma: an aggressive course for a benign tumor

A 79-year-old female presented with difficulty ambulating and was found to have weakness and hyperreflexia in the lower extremities. Magnetic resonance imaging (MRI) revealed a large T8-T9 intraspinal tumor. She underwent a thoracic laminectomy, and excision of an intradural extramedullary lesion. The surgical specimen was soft, black tissue that consisted of a moderately cellular, deeply pigmented tumor. The neoplastic cells proved to be melanocytic, and were devoid of overt features of anaplasia, i.e., prominent nuclear pleomorphism, necrosis, significant mitotic activity, and high proliferation indices. Four months postoperatively, MRI demonstrated focal areas of enhancement in the conus medullaris and in the fourth ventricle, indicating leptomeningeal spread. Subsequently, the patient underwent whole brain radiation. On repeat imaging, there was nodular enhancement of the fourth ventricle and throughout the spinal cord. Despite chemotherapy and radiation therapy, the disease advanced and the patient expired. Meningeal melanocytoma is a rare, histologically benign tumor with good prognosis. However, local aggressive behavior has been recorded, especially in cases of subtotal gross resection. On a literature review, there was one case of cranial posterior fossa meningeal melanocytoma with associated lesions in both suprarenal glands and the left kidney, but there were no cases with distant metastasis. In this report, we present an unusual case of spinal meningeal melanocytoma with diffuse spread throughout the craniospinal axis that proved to be fatal.

Meningeal melanocytoma of the brain and oculodermal melanocytosis (nevus of Ota): case report and literature review

BACKGROUND

Meningeal melanocytomas are rare benign pigmented tumors of meningeal melanocytes. Nevus of Ota is a melanocytic pigmentation of the sclera and the skin adjacent to the eye. We report a rare case of parietal convexity meningeal melanocytoma associated with ipsilateral mucocutaneous melanosis and review the literature.

METHODS

A 17-year-old man presented with headache and blindness. There was left scalp and facial mucocutaneous melanosis. During surgery, speckled hyperpigmentation was seen in all layers of the scalp, bone, dura, and even ependyma. Pathologic examination of the tumor and scalp consisted of light microscopy and immunohistochemistry. In a literature review, the demographics (age, sex), clinical characteristics (site of lesion, duration of symptoms), therapeutic options (surgical excision, radiotherapy), and prognosis (recurrence, death, death related to the disease, and follow-up) were analyzed. For statistical analysis we used the independent sample t-test and chi(2) tests.

RESULTS

Ninety-five cases (45 intracranial and 50 spinal) of meningeal melanocytoma have been reported. The median age of patients with intracranial lesions (40 years) was significantly lower than that of patients with spinal lesions (49 years) (p = 0.016). Of the 95 patients, 57.9% were female. In the nervous system, melanocytes are more common in the infratentorial and cervical areas, but more than half of the tumors have been located in the supratentorial region and the thoracic spine. In 46 months median follow-up, tumor recurrence rate and tumor related death rate were 26.3% and 10.5%, respectively. These were not statistically significant for different therapeutic modalities. There was a trend toward shorter survival for patients who underwent subtotal tumor resection without radiotherapy compared with other groups.

CONCLUSION

The prognostic criteria, differential diagnosis, and the embryological aspects of meningeal melanocytoma are discussed with a review of the related literature.

Cerebral mass due to neurocutaneous melanosis: eight years later

Neurocutaneous melanosis (NCM) is associated most commonly with giant congenital melanocytic nevi (CMN), in particular those on the scalp or in a posterior axial location that are accompanied by satellite congenital nevi. It also can occur in patients with multiple medium-sized CMN. In general, the prognosis of those with symptomatic NCM is poor, even in the absence of malignancy, while the prognosis of those with asymptomatic NCM detected via screening varies and is more difficult to predict. Herein we report an asymptomatic patient with a giant CMN and multiple satellite nevi who had a screening magnetic resonance imaging (MRI) study at age 5 months that showed a rounded area of increased signal in the right temporal lobe on T1-weighted images, suggestive of parenchymal melanosis. This melanotic mass was resected at age 10 months, and histologic examination of the surgical specimen showed prominent perivascular collections of benign, pigment-containing melanocytes within cerebral tissue. The patient remains healthy 8 years later. His excellent long-term outcome and other reports of NCM with localized central nervous system (CNS) involvement apparent on MRI may have implications for management, including early imaging of patients with high-risk CMN and potential surgical intervention for NCM.

Giant congenital melanocytic naevus and symptomatic thoracic arachnoid cyst

A 43-year-old female with multiple congenital naevi presented with a 5-year history of right upper quadrant pain. Magnetic resonance imaging demonstrated a large epidural thoracic arachnoid cyst. This case highlights the need to consider that the management of patients with giant congenital melanocytic naevus is variable depending on the age of the patient, the location of lesions and the presence of complications such as neurocutaneous melanosis. The value of magnetic resonance scanning as a screening device is discussed.

Syndromes associated with melanocytic nevi

Melanocytic nevi have been reported in association with several congenital syndromes. This review describes the clinical and cutaneous manifestations of six syndromes associated with congenital melanocytic nevi, two associated with acquired nevi, and six associated with melanocytic nevi in which insufficient evidence exists to classify them as congenital or acquired. It is important to recognize these associations to evaluate and counsel patients with melanocytic nevi. Early recognition will also facilitate timely intervention.

Giant congenital nevus and chronic progressive ascending hemiparesis (Mills syndrome). Report of a case

We describe the case of a 20 year old boy with a giant congenital nevus who developed a chronic progressive ascending hemiparesis. The association of the pigmented lesion with a focal neurological deficit is pathognomonic for neurocutaneous melanosis complicated by a leptomeningeal melanoma. MR imaging at 1.5 tesla ruled out such a possibility and showed a small aspecific pontine lesion along the route of the corticospinal tract. We discuss possible etiologies.

Neurocutaneous melanosis: definition and review of the literature

Neurocutaneous melanosis is a rare congenital syndrome characterized by the presence of large or multiple congenital melanocytic nevi and benign or malignant pigment cell tumors of the leptomeninges. The syndrome is thought to represent an error in the morphogenesis of the embryonal neuroectoderm. We review 39 reported cases of neurocutaneous melanosis and propose revised criteria for diagnosis. Most patients with neurocutaneous melanosis presented in the first 2 years of life with neurologic manifestations of increased intracranial pressure, mass lesions, or spinal cord compression. Leptomeningeal melanoma was present in 62% of the cases, but even in the absence of melanoma, symptomatic neurocutaneous melanosis had an extremely poor prognosis. Useful diagnostic procedures include cerebrospinal fluid cytology and magnetic resonance imaging with gadolinium contrast. Patients may be aided by palliative measures such as shunt placement to reduce intracranial pressure. Dermatologists in their follow-up of patients with large or multiple congenital melanocytic nevi should be aware of this condition, to aid in prompt diagnosis and because the treatment of cutaneous lesions may be altered in the presence of symptomatic neurocutaneous melanosis.

Neurocutaneous melanosis associated with intraspinal lipoma

A case of neurocutaneous melanosis developing a leptomeningeal melanoma is described in a ten year old girl in whom an intraspinal lipoma had been resected seven years earlier. Standard and CT myelographic findings are described and the complementary role of Gadolinium-enhanced MRI is discussed. The literature is reviewed and the association of a lipoma and neurocutaneous melanosis has not been encountered.

Intraspinal melanotic arachnoid cyst and lipoma in neurocutaneous melanosis

A 22-year-old woman with neurocutaneous melanosis is reported in whom an intraspinal melanotic congenital arachnoid cyst and melanotic lipoma occurred at the same thoracic location. Such combined occurrence of lesions of the central nervous system, producing compression of the spinal cord, has not been noted in any previously reported case of neurocutaneous melanosis. The pathogenesis of these two unusual melanotic lesions is discussed in relation to the ectomesenchymal properties of the neural crest. The concurrent melanotic arachnoid cyst and lipoma, in juxtaposition, were demonstrated by a computed tomography scan in which the preoperative diagnosis of lipoma was possible through the density of the lesion.

Association of ganglioneuroblastoma with syringomyelia. Case report

The association of a syndrome of a degenerative nature such as syringomyelia and a neuroblastoma can be of clinical interest. We will describe the case of a young female suffering from a retroperitoneal neuroblastoma and secondary development of syringomyelia. The possible pathogenetic link between these two pathologies will be discussed. Firstly, the dysontogenetic interpretation will be underlined. Other hypotheses will concentrate on the presence of tumors within the cord, which tend to cavitate, and furthermore, on the association between the edema and some diseases such as neoplasma, traumas, and on arachnoiditis as a major pathogenetic factor in syringomyelia. The existence of a possible link between arachnoiditis and the radiotherapy received by the patient after the surgical excision of the retroperitoneal neuroblastoma, will be discussed. Lastly a further pathogenetic hypothesis will be pointed out: an intramedullary softening due to disturbed blood supply, caused by the extramedullary neoplasm.