neurocutaneous melanosis ( ncm ) is a rare , non - familial , congenital syndrome , first described by rokitansky in 1861(1 ) . multiple ( three or more ) or large congenital nevi ( measuring equal to or greater than 9 cm on the scalp , or 6 cm or greater on the body ) with melanin - containing cells in the leptomeninges ( melanosis or melanoma ) are accepted as the diagnostic criteria ( 2 ) . the giant congenital melanocytic nevi ( gcmn ) occurs in approximately 1/20.000 of the live births ( 2 ) . cns involvement is basically diagnosed by imaging , especially by mri . in this report , we present a neonatal female with gcmn and cns melanosis . brain lesions were primarily diagnosed by cranial ultrasound ( us ) 3 days after birth . a female infant was born in our hospital by vaginal delivery at 39 weeks of gestation to a primiparous 21-year - old mother who had not received prenatal care before delivery . the largest nevus covered nearly the entire back ( 2115 cm ) extending inferiorly from the upper back to the buttocks and anteriorly to the trunk , wrapping the lower abdomen and proximal thigh . a few hundreds of satellite lesions , 1 mm to 5 cm in diameter , were scattered over the body , scalp and extremities ( figure 1 ) . the birth weight was 2870 gr , the head circumference was 32 cm and the total body length was 49 cm . cranial us ( ge healthcare 's logiq p5 portable ultrasound system ) , which was done via the anterior fontanelle from coronal and parasagittal views , demonstrated bilateral , multiple echogenic intra - parenchymal lesions with smooth margins . these 4 - 24 mm in diameter lesions were present in both temporal lobes , the basal ganglia and the white matter of the cerebellum ( figure 2 ) . based on the us findings , mri of the brain and the spine was performed . the examination was performed on a 1.5 tesla mri equipment ( philips best the netherlands ) with the following sequences : sagittal mprage , axial tse t2 , axial echo planar , diffusion tensor imaging , axial t1-weighed ( t1w ) images before and after contrast ( gadolinium dimeglumine - magnevist ) as well as enhanced coronal and sagittal t1w images of the brain . t1w enhanced images of the spine were also obtained . leptomeningeal involvement was easily seen on t1w images as gyral hyperintensities , especially in the parieto - occipital sulci and subarachnoid spaces . it was not thick , plaque - like or nodular , which was a feature of benign involvement . parenchymal involvement appeared as multiple nodular lesions involving the dentate nucleus bilaterally , the right cerebellar hemisphere peripherally , the right internal capsule , left thalamus , medial temporal lobe bilaterally , right middle cerebellar pedicle , left frontal lobe , parieto - occipital sulci and subependymal regions characterized by hyperintensities on t1w images and low signal on t2w images ( figures 3 - 6 ) . the lesions were easily seen on t1w images and they did not enhance significantly . the biggest lesion was located on the left thalamus that was also easily seen on us examination . the patient is healthy without seizures and followed up by departments of pediatric neurology , dermatology and plastic surgery . patients who have large cutaneous lesions particularly over the back , neck or scalp and multiple ( more than three ) nevi have been shown to have a greater risk for neural involvement ( 3 ) . the present case had large cutaneous lesions especially over the back , which is a risk factor for cns melanosis . these infants have been defined to have normal physical examination except for skin lesions at birth ( 2 ) . but in the first two years of life , the patients with intracranial lesions show neurological manifestations of increased pressure due to poor resorption of the cerebrospinal fluid ( csf ) , mass lesions or spinal cord compression ( 2).these abnormalities typically manifest as seizures , hydrocephalus , developmental delay and delay of motor movements ( 2).symptomatic cns melanosis , even in the absence of malign transformation , has an extremely poor prognosis ( 2 ) . it is important to diagnose the cranial lesions at birth if present , since it helps to diagnose the clinical manifestations earlier . although cns melanosis is best seen on mri scan , ultrasound is useful in newborns for early diagnosis due to the availability and ease of use . in our case , lesions were echogenic with smooth borders and without a mass effect . echogenic foci in the brain parenchyma may be seen in some pathologies such as tuberous sclerosis , candidal infection and petechial hemorrhage . definitive diagnosis of neural involvement is made by identification of melanocytes by csf sampling or meningeal biopsy . however , in practice , craniospinal lesions seen on mri of a baby with cutaneous nevus highly suggests ncm . melanin deposits in the brain usually lead to severe shortening of t1 relaxation time due to the paramagnetic effect . it was revealed to be the result of the presence of stable free radicals in melanin ( 4 ) . gradient echo sequence may show a focal blooming or susceptibility artifact due to the presence of melanin and hemorrhage ( 5 ) . in this case , us was used to show whether cranial lesions exist , but mri was superior to us since it showed leptomeningeal involvement and also the extent of cranial lesions . in us , we could not see very small lesions in the cerebellum because of bone artifact . in ncm , melanocyte deposition can be found in the pia and arachnoid , most commonly over the base of the brain , in the basal ganglia , dentate nuclei , cerebellar hemispheres , pons , thalami , amygdala and basal frontal lobes ( 6 ) . in addition to intracranial leptomeningeal involvement , intraspinal leptomeningeal , ventricular ependymal and choroid plexus involvement may occur . the true incidence of spinal involvement in patients with melanocytic nevi is unknown , but in some reports spinal involvement was revealed to be 20% of the cases ( 1 ) . by mri imaging , the spectrum of neural involvement can be understood . knowing these locations helps to differentiate melanotic deposits that are part of the disease , from metastases secondary to malignant degeneration of a gcmn . it is not always possible to differentiate primary malign melanoma from metastatic lesions by mri . the usual appearances of metastatic malignant melanoma on mri include the melanotic and amelanotic patterns . the melanotic pattern consists of high signal intensity on t1w and low signal intensity on t2w images . in the amelanotic pattern , the lesion is hypointense or isointense to the cortex on t1w images and hyperintense or isointense to the cortex on t2w images . primary melanoma does not always have a homogeneous pattern on mri ; its appearance may depend on the degree of melanin or previous hemorrhage within the lesion . it is usually hyperintense on t1w and iso- to hypointense on t2w with contrast enhancement . focal nodular or thick plaque - like meningeal enhancement and contrast enhancement of intracranial lesions may represent malign transformation ( 4 ) . additionally , any growth of pre - existing lesions , edema or necrosis in the lesions is suspicious of malignant transformation ( 2 ) . in our case , the overall incidence of malignancy within the involved meninges is estimated to be as high as 50% ( 7 ) . although absent in our patient , tethered spinal cord , syringomyelia , and structural abnormalities , particularly dandy walker malformation , encephalocele , arachnoid cysts , and chiari type 1 malformation have been reported to be associated with ncm ( 8 , 9 ) . the exact pathogenesis of the association of dandy walker complex ( dwc ) with ncm is unknown . however , the most widely accepted hypothesis is that leptomeningeal melanosis prevents the normal inductive effects of primitive meningeal cells on the deposition of extracellular matrix , neuronal cell migration , and formation of normal basal csf resorption pathways , thus resulting in the vermian hypogenesis and retrocerebellar cyst formation characteristic of dwc ( 10 ) . cns melanosis has no specific treatment at present , but its early detection prevents aggressive surgical treatment of cutaneous lesions . a child with cns melanoma on initial scan , as in the present case , must be examined every 6 months regularly for neurological signs by serial mris to detect malign transformation . early detection of a cns malignancy enables surgical resection of the tumor . in conclusion , there are not so many cases like this in the literature , in which the diagnosis of ncm is made by us in the first days after birth . in our case , intracranial lesions were disseminated and bigger in size compared with the other cases in the literature .
neurocutaneous melanosis ( ncm ) is a rare , congenital non - hereditary syndrome , characterized by multiple pigmented nevi . 
 we report the radiologic findings of a newborn who had extensive cutaneous melanotic nevus with satellite lesions in the brain . 
 ultrasound showed multiple echogenic foci in the cerebral parenchyma . 
 subsequent mri confirmed these lesions as characteristic deposits of melanin . 
 the infant was asymptomatic , but presence of risk factors such as malign transformation or neurological manifestations makes early diagnosis very important . 
 we present this case to emphasize on the radiological findings of this syndrome in order to reach an early diagnosis .