Cerebellar amelanotic melanoma can mimic cerebellar abscess in a pediatric case of neurocutaneous melanosis

Abstract

Neurocutaneous melanosis (NCM) is a rare phakomatosis that may be associated with intracerebral masses. The differential diagnosis of intracerebral masses in NCM is often challenging and should include pigmented and nonpigmented lesions.

Keywords: adolescent medicine; neurology; paediatrics.

FIGURE 1

MR and CT scan of our 10‐month‐old patient with Neurocutaneous Melanosis and hydrocephalus. Axial T1‐weighted images (A‐D) MRI show a 10‐month‐old girl patient with hydrocephalus (white asterisk) and accumulation of melanin that presents with hyperintense signal (white arrowheads) in the insula (A), in the thalamus (B), in the retro‐thalamic cistern (C), and in the amygdala bilaterally (D). Axial T2‐weighted image of the same MRI acquisition (E) shows hypointense signal of melanin accumulation in the thalamic region (black arrow head) and hydrocephalus (black asterisk). After ventriculoperitoneal shunt placement (white arrow), axial CT scan (F) shows decrement of hydrocephalus (white asterisk), hyperdensity of the retro‐thalamic cistern (white arrow head), and bilaterally frontal hygroma (black arrow head)

FIGURE 2

MR TFE‐3D T1‐weighted images of our 6‐year‐old patient with Neurocutaneous Melanosis. Axial (A), sagittal (B), and coronal (C) planes of T1‐weighted images show a 6‐year‐old girl patient with melanin intraparenchymal and leptomeningeal accumulation. White arrowheads show melanin hyperintensity in the amigdala bilaterally, in the thalamic and retro‐thalamic cistern. In (B) leptomeningeal hyperintensity as manifestation of leptomeningeal melanosis in the left temporal lobe is well depicted (empty arrowheads)

FIGURE 3

MR and CT scan of our 8‐year‐old patient with Neurocutaneous Melanosis and a new onset left hemispheric cerebellar lesion. Multiplanar CT scans (A‐C) show a hyperdense focal round lesion (white arrowhead) in the left cerebellar hemisphere. T1‐weighted images (F‐H) confirmed a hypointense round lesion (white arrowhead), mildly hyperintense in T2 (i,m,q) and in FLAIR images (J‐L), surrounded by edema (white arrowhead). EPI‐DWI (b = 1000s/mm²) (D) and ADC map (E) demonstrate diffusion restriction of the lesion (white arrowhead). In (H) leptomeningeal melanin infiltration is well depicted as leptomeningeal hyperintensity (empty arrowheads) in the left temporal lobe. Postcontrast multiplanar TFE‐3D T1‐weighted images (N‐P) show the lesion in the left cerebellar hemisphere with inhomogeneous enhancement (white arrowhead)