Small- and medium-vessel vasculitis is a common manifestation in systemic lupus erythematosus (SLE) and may occur in any organ. However, acute acalculous cholecystitis is a rare abdominal manifestation in SLE, especially in children. We report a case of a 12-year-old patient who initially presented with AAC and seizure. Follow-up investigation diagnosed SLE, and brain magnetic resonance imaging had hyperintense white matter lesions in cortico-subcortical regions. The patient was successfully treated with pulse methylprednisolone and cyclophosphamide without surgical intervention.