Introduction: X-linked adrenoleukodystrophy (X-ALD) is a recessive neurodegenerative disease with impaired beta-oxidation of very long-chain fatty acids (VLCFA). The typical presentation is symmetrical parieto-occipital white matter lesions in magnetic resonance imaging (MRI), but a few rare cases of atypical clinical presentation and neuroimaging were described.

Case description: A ten-year-old boy, the only son of non-consanguineous marriage, presented with aggressive behavior and right hemiparesis. The MRI showed white matter lesion in left hemisphere. He was initially diagnosed as acute demyelinating encephalomielopathy (ADEM) and treated with steroids with little results. The boy later presented with worsening of clinical features, epileptic seizures and loss of speech. The mother reported darkening of the skin. At nine months after the beginning of the symptoms he was seen in our service. Another MRI was performed, showing white matter lesion in bilateral frontal lobes with extension along cortifugal pathways, left parietal lobe and midbrain with periperal enhancement. The cerebrospinal fluid was normal and electroencephalogram showed right epileptic activity. He underwent brain biopsy with unspecific inflammatory changes and blood screening with high levels of VLCFA confirmed the diagnosis.

Discussion: Atypical forms of X-ALD were described in less than 5% of cases, including only frontal lesions and asymmetric involvement. In these situations differential diagnosis with neoplastic processes can be challenging and delay in diagnosis is frequent. In our case, the skin changes suggestive of adrenal insufficiency and the absence of brain edema alerted to the diagnosis of X-ALD.