Journal of Dr. NTR University of Health Sciences

CASE REPORT
Year
: 2016  |  Volume : 5  |  Issue : 1  |  Page : 63--66

Neurocutaneous melanosis with Dandy-Walker malformation: A rare case report


Sandeep Velicheti1, Sonylal Erwin Palaparthy2, Rabiya Nelofer1, Ashirwad Pasumarthy1,  
1 Department of Radiodiagnosis, Dr. Pinnamaneni Siddhartha Institute of Medical Sciences, Vijayawada, Andhra Pradesh, India
2 Department of Neurosurgery, Dr. Pinnamaneni Siddhartha Institute of Medical Sciences, Vijayawada, Andhra Pradesh, India

Correspondence Address:
Sandeep Velicheti
Department of Radiodiagnosis, Dr. Pinnamaneni Siddhartha Institute of Medical Sciences, Chinnoutpally, Vijayawada, Andhra Pradesh
India

Abstract

Neurocutaneous melanosis is a rare congenital disorder characterized by the presence of large or multiple congenital melanocytic cutaneous nevi associated with intracranial leptomeningeal melanocytosis. An association with Dandy-Walker malformation has been reported in 8-10% of children with neurocutaneous melanosis. [1] The main objective of this case report is to present the rare association as only few cases have been reported in literature, besides, as well, to discuss this as a case that appeared to be as meningitis with posterior fossa cystic malformation but turned out as neurocutaneous melanosis with Dandy-Walker malformation. In addition, we wanted to highlight the importance of correlating clinical examination findings with imaging findings and not limiting to imaging findings alone.



How to cite this article:
Velicheti S, Palaparthy SE, Nelofer R, Pasumarthy A. Neurocutaneous melanosis with Dandy-Walker malformation: A rare case report .J NTR Univ Health Sci 2016;5:63-66


How to cite this URL:
Velicheti S, Palaparthy SE, Nelofer R, Pasumarthy A. Neurocutaneous melanosis with Dandy-Walker malformation: A rare case report . J NTR Univ Health Sci [serial online] 2016 [cited 2022 Oct 5 ];5:63-66
Available from: https://www.jdrntruhs.org/text.asp?2016/5/1/63/178983


Full Text

 INTRODUCTION



Neurocutaneous melanosis is a rare congenital disorder characterized by the presence of large or multiple congenital melanocytic cutaneous nevi associated with intracranial leptomeningeal melanocytosis. Histopathologic examination shows accumulation of melanotic cells in the arachnoid and pia mater. This is extending over the ventral surface of the mesencephalon, pons, medulla, and cerebellum, and the upper cervical spinal and lumbosacral cord, resulting in leptomeningeal melanosis. [1]

 CASE REPORT



A 17-year-old male presented with diffuse pounding headache that had gradually worsened since 2 months, and squint and diplopia since 15 days. Ophthalmic examination revealed bilateral papilledema. No clinical history of seizures, developmental delay, or mental retardation was noted in the past. There was no other focal neurological deficit. Laboratory studies revealed mildly elevated white blood cells (WBCs) with a predominance of neutrophils (86%) and elevated erythrocyte sedimentation rate (ESR) (15 mm/1st h).

Contrast-enhanced (CE) magnetic resonance imaging (MRI) of the brain showed extensive spinal and diffuse intracranial meningitis type of pattern evident by diffuse leptomeningeal enhancement, more so in the posterior fossa causing extraventricular obstructive (communicating) hydrocephalus [Figure 1]a-c. Large posterior fossa cyst was seen communicating with enlarged inferior part of the fourth ventricle through hypoplastic inferior vermis which is the Dandy-Walker continuum. Enlarged prepontine and premedullary cisterns were seen compressing the brainstem [Figure 2]a and b. T1-weighted, T2-weighted, CE T1-weighted images showed right cerebellomedullary angle nodule that was hypointense on T1W and was intensely enhancing with contrast [Figure 3]a-c. T2-weighted fluid attenuated inversion recovery (FLAIR) images reconfirmed cerebrospinal fluid (CSF) nature of the cyst and showed features of basal and supratentorial meningitis (Ivy sign) [Figure 4]a-c.{Figure 1}{Figure 2}{Figure 3}{Figure 4}

Examination revealed a few more clinical details such as the presence of multiple cutaneous nevi over the scalp, the back, and the thorax. These were present at birth and progressively increased in size with the growth of the patient [Figure 5]a and b.{Figure 5}

Screening of the whole spine was done. Plain study of the whole spine revealed T1 hyperintensity in the cauda equina at the sacral level [Figure 6]a]. On contrast study, intense meningeal enhancement was seen [Figure 6]b and c. Initially, the possibility of granulomatous meningitis with cysts and nodules, were considered most likely to be tuberculosis (or) Racemose cysticercosis. {Figure 6}

The patient was posted for surgery to relieve the hydrocephalus. Surgery revealed black cystic lesion that is partially excised to relieve the pressure followed by the dural repair [Figure 7]a and b]. Histopathological specimen showed the presence of extensive melanocytes in the leptomeninges [Figure 8]a and b. Based up on the clinical, surgical, and pathological findings, the diagnosis of neurocutaneous melanosis with Dandy-Walker malformation was made.{Figure 7}{Figure 8}

 DISCUSSION



According to Fox H, neurocutaneous melanosis is a rare phacomatosis comprising of pigmented nevi on the skin and leptomeningeal melanosis or melanoma. [2] However, no evidence of malignancy in the skin lesions and no involvement of other nonmeningeal organs were noted. [2]

Fox H proposed several diagnostic criteria. [2]

The presence of large or multiple congenital melanocytic nevi (one of which is at least 20 cm in diameter) with benign (melanosis) or malignant (melanoma) central nervous system (CNS) tumors.

Absent melanomatous malignant involvement of the skin.

No evidence of malignant melanoma in any organ outside the CNS. [2] The disease may be associated with another neurocutaneous syndrome such as Sturge-Weber or Von Recklinghausen's disease. [3]

An association with Dandy-Walker malformation (hypoplasia or absence of the cerebellar vermis, hypoplasia of cerebellar hemispheres, large fourth ventricle, and large posterior fossa) has been reported in 8-10% of children with neurocutaneous melanosis. The exact pathogenesis for this association is unknown. [1]

Histopathological examination shows accumulation of melanotic cells in the basal arachnoid and pia mater. This is spread over the ventral surface of the mesencephalon, pons, medulla, and cerebellum, and the upper cervical spinal and lumbosacral cord, resulting in leptomeningeal melanosis. Parenchymal melanin deposits probably represent melanocytes in the perivascular spaces. The anterior temporal lobes, and particularly the amygdala, seem to be the most frequent locations for parenchymal melanocytic accumulation. Other preferential sites include the cerebellum, thalami, and the base of the frontal lobe. [4],[5] Cranial nerve palsy is associated frequently. Subdural or parenchymal hemorrhage or both syringomyelia and spinal arachnoiditis can complicate the clinical presentation. [6] Hydrocephalus occurs in the majority of patients, because of meningeal thickening from CSF outflow obstruction or decreased CSF resorption. [4],[6]

The imaging clue to the diagnosis of leptomeningeal melanosis or parenchymal melanin deposits is T1 shortening on magnetic resonance (MR). Authors attribute T1 shortening to paramagnetic free radicals known to occur in melanin. [7] Isiklar et al. stated that only the minority of melanoma metastases have the anticipated MR pattern of T1 shortening. The majority of tumors that exhibit this melanotic pattern have more than 10% of melanin-containing cells. [8]

Differentiation between benign and malignant parenchymal melanocytosis on MR is difficult. Necrosis, edema, and hemorrhage are suggestive of malignancy, but can be absent in malignant melanomas. [5],[9] Leptomeningeal enhancement is not pathognomonic for leptomeningeal melanosis. It can be seen in infectious and metastatic diseases and in cases of primary brain tumor. It is not possible to differentiate a benign tumor from a malignant tumor.

Leptomeningeal melanosis with MR imaging. [10]

Follow-up with serial neurologic examination and imaging studies is advised. Surgical intervention must be considered only if the evidence of progression is documented. [5] The prognosis for patients with Dandy-Walker malformation and neurocutaneous melanosis is extremely poor, with all reported patients dying by 4 years of age from malignant transformation of the melanosis. The nodule at cerebellomedullary cistern in our case could be a melanoma as well.

Acknowledgements

We acknowledge Dr. B.N. Chander and Department of Radiodiagnosis, Dr. Pinnamaneni Siddhartha Institute of Medical Sciences, for their valuable support.

We acknowledge Dr. Kalyan Chakravarthy and Dr. Sudarshan, Department of Pathology and Department of Surgery, Pinnamaneni Siddhartha Institute of Medical Sciences for their valuable support.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Smith AB, Rushing EJ, Smirniotopoulos JG. Pigmented lesions of the central nervous system: Radiologic-pathologic correlation. Radio Graphics 2009;29:1503-24.
2Fox H. Neurocutaneous melanosis. In: Vinken PJ, Bruyn GW, editors. Handbook of Clinical Neurology Amsterdam. North Holland publishers; 1972. p. 414-28.
3Novotny EJ Jr, Urich H. The coincidence of neurocutaneous melanosis and encephalofacial angiomatosis. Clin Neuropathol 1986;5:246-51.
4Demirci A, Kawamura Y, Sze G, Duncan C. MR of parenchymal neurocutaneous melanosis. AJNR Am J Neuroradiol 1995;16:603-6.
5Barkovich AJ, Frieden IJ, Williams ML. MR of neurocutaneous melanosis. AJNR Am J Neuroradiol 1995;15:859-67.
6Poe LB, Roitberg D, Galyon DD. Neurocutaneous melanosis presenting as an intradural mass of the cervical canal: Magnetic resonance features and the presence of melanin as a clue to diagnosis: Case report. Neurosurgery 1994;35:741-3.
7Enochs WS, Petherick P, Bogdanova A, Mohr U, Weissleder R. Paramagnetic metal scavenging by melanin: MR Imaging. Radiology 1997;204:417-23.
8Isiklar I, Leeds NE, Fuller GN, Kumar AJ. Intracranial metastatic melanoma: Correlation between MR imaging characteristics and melanin content. AJR Am J Roentgenol 1995;165:1503-12.
9Sebag G, Dubois J, Pfister P, Brunelle F, St-Rose C. Neurocutaneous melanosis and temporal lobe tumor in a child: MR study. AJNR Am J Neuroradiol 1991;12:699-700.
10Byrd SE, Darling CF, Tomita T, Chou P, de Leon GA, Radkowski MA. MR imaging of symptomatic neurocutaneous melanosis in children. Pediatr Radiol 1997;27:39-44.