In “Severe hyperhomocysteinemia manifesting as moyamoya vasculopathy and Henoch-Schonlein purpura,” Cho et al. described a 37-year-old woman with a history of Henoch-Schonlein purpura with leukocytoclastic vasculitis and immune mesangiopathic glomerulonephritis who presented with recurrent ischemic infarcts and was found to have hyperhomocysteinemia due to homozygous cystathionine β-synthase (CBS), then developed moyamoya vasculopathy requiring a direct bypass on the left and an encephalo-duro-arterio-synangiosis procedure on the right. The authors suggested that the cerebral, skin, and renal changes are all the result of CBS deficiency. In review of this case, Drs. Gaillard and Arquizan postulate that the underlying mechanism was likely a systemic vasculitis with CNS involvement and question whether (1) inflammatory markers, autoantibodies, and serologies were checked in serum or CSF, (2) a brain biopsy was obtained, or (3) a trial of steroids or immunosuppressants was given. Cho et al. respond that (1) serial cerebral angiograms showed progressive intracranial stenosis consistent with moyamoya vasculopathy, not with vasculitis, and (2) CSF showed no pleocytosis, and inflammatory and infectious tests were negative. They note that there was no recurrence of skin or renal events despite the absence of systemic therapy, making the diagnosis of secondary CNS vasculitis unlikely. While both Cho et al. and Drs. Gaillard and Arquizan agree that the high-resolution MRI was suggestive of vasculitis, Cho et al. believe it is consistent with a moyamoya-like vasculopathy and that this case represents a new phenotype of CBS deficiency.

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