Short CommunicationNeuromyelitis optica, atypical hemophagocytic lymphohistiocytosis and heterozygous perforin A91V mutation

- First report of hemophagocytic lymphohistiocytosis complicating neuromyelitis optica
- Awareness of atypical HLH need to be raised, especially in patients with autoimmune disease
- Flow cytometry for perforin is able to recognize common hypomorphic mutations like A91V.

Neuromyelitis optica is an autoimmune demyelinating inflammatory disease characterized by optic neuritis and myelitis with anti-aquaporin 4 antibodies. Hemophagocytic lymphohistiocytosis is a severe systemic inflammatory syndrome that can present in a genetic primary form or secondarily to infective, neoplastic or autoimmune diseases. Our case discusses the first reported case of atypical late-onset hemophagocytic lymphohistiocytosis in a patient with neuromyelitis optica, with multiple triggering factors and carrying the common A91V hypomorphic perforin mutation, that blurs the distinction between primary and secondary forms.

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