Rapidly progressive glucocorticoid-resistant childhood-primary angiitis of the central nervous system positive for HLA-B51 and A26: a case report.

Primary angiitis of the central nervous system (PACNS) is a rare inflammatory vasculitis localised to the central nervous system. Treatment of severe PACNS often includes glucocorticoids and cyclophosphamide; however, some cases exhibit resistance to glucocorticoids, leading to severe neurological sequelae. In this case report, a 14-year-old female patient presented with fever, headache, and short-term memory loss. Her blood test results showed no significant abnormalities. HLA-B51 and A26 were both positive. Cerebrospinal fluid examination showed no elevated interleukin-6. Brain magnetic resonance imaging with fluid-attenuated inversion recovery sequences demonstrated hyperintense signals in the bilateral basal ganglia, left thalamus, and insula. Contrast-enhanced T1-weighted imaging showed peripheral enhancement of the lesions. Given the possibility of a demyelinating disorder, glucocorticoids were administered. However, the patient remained febrile, and magnetic resonance imaging (MRI) revealed disease progression. To differentiate infectious and malignant diseases, a biopsy of the left thalamic lesion was performed. Histopathological examination revealed coexisting lymphocytic and granulocytic vasculitis affecting small arteries and arterioles. Based on the clinical course and laboratory results, the patient was diagnosed with PACNS. Despite intravenous immunoglobulin, intravenous cyclophosphamide, and rituximab, the patient became comatose, and the brain MRI worsened. Following infliximab, clinical symptoms and brain MRI improved. The clinical course suggests that infliximab was effective for this patient with glucocorticoid-resistant PACNS. As potential associations have been previously reported between HLA-B51/A26 and vasculitis in Behçet disease, our case may suggest a pathophysiological link between vascular-BD and a subset of PACNS, which may also explain the good clinical response to infliximab. Further research is warranted to address this hypothesis.