Hypomelanosis of Ito–Brain Melanin Deposition on Magnetic Resonance Imaging: A Preliminary Hypothesis Based on Two Pediatric Cases

To investigate brain melanin deposition on magnetic resonance imaging (MRI) in hypomelanosis of Ito (HI) by presenting two clinical cases and reviewing relevant literature. Two patients clinically diagnosed with HI underwent comprehensive neurological and systemic evaluations. Detailed MRI was performed to identify parenchymal changes suggestive of melanin deposition. A literature review was conducted to compare the imaging findings and discuss embryological and neurocutaneous correlations. Both cases presented with typical hypopigmented cutaneous lesions but without dysmorphic features. MRI of the first child revealed left hemimegalencephaly, diffuse white matter abnormalities, and multiple nodular lesions that were T2-hypointense and T1-hyperintense, suggesting possible intracranial melanosis. In contrast, MRI of the second patient demonstrated T2 hyperintensities in the juxtacortical white matter of the medial occipital lobe with blooming on susceptibility-weighted imaging sequences; however, hemimegalencephaly was absent. Histological confirmation was not possible due to lack of consent for brain biopsy. We report a rare case of probable intracranial melanin deposition in HI, inferred from characteristic MRI signal patterns. These findings may reflect aberrant melanocyte migration into the brain, consistent with their shared neural crest origin with neurons. Although histopathological verification was not feasible, our observations underscore the need for further pathological validation and exploration of the neurocutaneous interface in pigmentary disorders.