Neurocutaneous Melanosis with Giant Congenital Melanocytic Nevi

A 5-year-old male child was reported with multiple (four to five) episodes of abnormal movements per day since 1 year of age and weakness of both lower limbs for the last 15 days. Physical examination revealed a giant, “cape-like” hairy nevus, with multiple satellite nevi. In total, the estimated surface area of the nevi was 60% of the total body surface ([Fig. 1]). On neurological examination, there was paraplegia; power in both lower limbs was ⅗. Deep tendon reflexes in both lower limbs were exaggerated and Babinski sign was positive. There was also bowel bladder involvement in the form of urinary retention with urinary catheter in situ. Laboratory testing revealed normal parameters. Contrast-enhanced magnetic resonance imaging (MRI) of the head and spine showed diffuse leptomeningeal thickening extending from the region of cervical 4 to the level of thoracic (T) 11, with displacement of the cord anteriorly within spinal canal, causing severe cord compression. The thickened meninges had areas of T1 brightness and were not suppressed on fat suppressed sequences indicative of melanomatosis ([Fig. 2A, B]). There was intense enhancement of meningeal lining on postcontrast sequences ([Fig. 2C, D]). MRI also showed enlarged posterior fossa with dilatation of inferior fourth ventricle with hypoplasia of cerebellar vermis suggesting the diagnosis of Dandy–Walker variant ([Fig. 2A]).

Fig. 1 Giant hairy nevus covering the whole back and extending to involve entire chest and proximal part of bilateral upper limbs. Multiple variable-sized nevi were seen on lower extremities, scalp, and face.

Fig. 2 Contrast-enhanced spine showed diffuse leptomeningeal thickening on T2-weighted (triangular arrow in A and B) extending from cervical 4 to thoracic 11 level causing severe cord compression and cord edema (A, star). Enlarged posterior fossa with dilatation of inferior fourth ventricle with hypoplasia of cerebellar vermis suggests Dandy–Walker variant (A). The thickened meninges had areas of T1 brightness (C, arrow). There was intense enhancement of meningeal lining on postcontrast sequences (bold arrow in D and lower row).

MRI of the brain revealed a T1 and T2 hyperintense lesion showing fat suppression in the region of the right cerebellopontine angle suggestive of lipoma. There were also areas of cortical T1 hyperintensities along bilateral basal temporal and frontal areas. Similar areas were also seen along bilateral cerebellar folia. These areas did not show fat suppression and in the clinical context represented areas of melanin deposition ([Fig. 3]). Skin biopsy from nevus in the neck area showed increase pigmentation in the dermis along with proliferation of melanocytic cells in deeper dermis, which was abnormal since melanocytic are limited to epidermis only and there was no evidence of malignant transformation ([Fig. 4]). A diagnosis of neurocutaneous melanosis (NCM) with giant congenital melanocytic nevi was made.

Fig. 3 Areas of cortical T1 hyperintensity along bilateral temporal and frontal areas and also along bilateral cerebellar folia (arrows). These areas did not show fat suppression.

Fig. 4 Hematoxylin and eosin-stained section of skin (40 × ) showing increase pigmentation in the dermis along with proliferation of melanocytic cells in deeper dermis (A). Hematoxylin and eosin-stained section (400 × ) showing proliferation of round to oval nevus cells in dermis (B).

NCM is a congenital disorder characterized by the presence of multiple congenital melanocytic nevi on the skin and melanocytic tumors in leptomeninges.[1] The lesions can be seen in central nervous system (cerebellum, cerebrum, amygdale, pons) and spinal cord, and symptoms can be in the form of headache, vomiting, and seizures along with features of raised intracranial tension and also involvement of various cranial nerves.[2] Most children with symptomatic NCM present within the first 5 years of life, with many presenting by 2 years of age.[3] Delayed presentation in older children, adolescents, and adults has also been reported, usually with symptoms such as headaches or neuropsychiatric manifestations.[4] With advances in imaging, the diagnosis of leptomeningeal melanosis can be made radiologically[5] in patients with suspected NCM, especially when they become symptomatic or when they have neurologic signs such as epilepsy, hydrocephalus, cranial palsies,[3] [6] and myelopathy.[7]

• References

• 1 Livingstone E, Claviez A, Spengler D , et al. Neurocutaneous melanosis: a fatal disease in early childhood. J Clin Oncol 2009; 27 (13) 2290-2291
• 2 Kadonaga JN, Frieden IJ. Neurocutaneous melanosis: definition and review of the literature. J Am Acad Dermatol 1991; 24 (5, Pt 1) 747-755
• 3 DeDavid M, Orlow SJ, Provost N , et al. Neurocutaneous melanosis: clinical features of large congenital melanocytic nevi in patients with manifest central nervous system melanosis. J Am Acad Dermatol 1996; 35 (4) 529-538
• 4 Makin GW, Eden OB, Lashford LS , et al. Leptomeningeal melanoma in childhood. Cancer 1999; 86 (5) 878-886
• 5 Rhodes RE, Friedman HS, Hatten Jr HP, Hockenberger B, Oakes WJ, Tomita T. Contrast-enhanced MR imaging of neurocutaneous melanosis. AJNR Am J Neuroradiol 1991; 12 (2) 380-382
• 6 Sebag 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 (4) 699-700
• 7 van Heuzen EP, Kaiser MC, de Slegte RG. Neurocutaneous melanosis associated with intraspinal lipoma. Neuroradiology 1989; 31 (4) 349-351