Objective: To report the clinical, pathological, and mutational features of hereditary C1 inhibitor (C1INH) deficiency as a cause of isolated vasculitic neuropathy.
Patient: A 35-year-old woman with sensorimotor mononeuritis multiplex and facial palsy.
Results: The sural nerve biopsy results showed a decrease of myelinated fibers with axonal degeneration and severe hypersensitivity vasculitis, with deposition of C1q on vessel walls. Mutational analysis of the C1INH gene found a new mutation, a heterozygous 2-base pair deletion in exon 8. The patient was treated with plasmapheresis and intravenous methylprednisolone, followed by oral prednisolone, which resulted in marked improvement.
Conclusion: Hereditary C1INH deficiency should be included in the differential diagnosis of nonsystemic vasculitis neuropathy.