Cytotoxic Lesions of the Corpus Callosum (CLOCC) in Siblings: A Case Report.

Introduction/background: Cytotoxic lesions of the corpus callosum (CLOCC) are a rare clinical-radiological syndrome, and cases occurring consecutively in siblings are exceptionally uncommon. This study reports two pediatric siblings with CLOCC (one experiencing two episodes), highlighting the potential role of genetic susceptibility in its pathogenesis. The findings contribute to the limited literature on familial CLOCC and recurrent cases, offering insights into its etiology and clinical variability.

Case presentation: Two brothers (aged 9 and 12) presented with sudden-onset aphasia and unilateral limb weakness, preceded by mild respiratory symptoms. Magnetic resonance imaging (MRI) revealed reversible lesions in the splenium of the corpus callosum and bilateral frontoparietal white matter, consistent with CLOCC. Both patients received immunomodulatory therapy (e.g., corticosteroids, intravenous immunoglobulin) and supportive care, achieving full neurological recovery within days. The elder sibling had a recurrence two years later with similar imaging findings. Laboratory tests ruled out common infections, and cerebrospinal fluid analysis was unremarkable.

Conclusion: This case underscores CLOCC as a heterogeneous condition with possible genetic predisposition, as evidenced by its occurrence in siblings. While prognosis is generally favorable, recurrence and familial clustering suggest the need for further research into underlying genetic or immunological mechanisms. Clinicians should consider CLOCC in children with acute neurological deficits and prior infections, even in the absence of typical biomarkers.