A case of severe chronic inflammatory demyelinating polyradiculoneuropathy with monoclonal gammopathy of undetermined significance with alternating immunoglobulin class to IgM from IgA.

A 71-year-old woman with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with IgA-λ monoclonal gammopathy of undetermined significance (MGUS) showed the acute development of tetraplegia, respiratory failure, and a marked fluctuation of the blood pressure. Intravenous (IV) high-dose steroid therapy (methylprednisolone: 1 g/day × 3 days), followed by oral prednisolone (PSL) (40 mg/day), and IV immunoglobulin (IVIg, 0.4 g/kg/day × 5 days) administrations resulted in the amelioration of these symptoms. However, they soon relapsed, which eventually led to complete tetraplegia and the need for mechanical ventilation. At this time, serum components of IgA-λ and IgM-λ were biclonally positive. Seven courses of plasma exchange and the alternative administration of dexamethasone (12 mg/day) and methtorexate (15 mg/week) were conducted, but with no significant improvement. Nine months after admission, she showed totally-locked in syndrome. Cryo-preserved serum obtained at this time showed high titers of IgM class antibodies against ganglioside (GD3 +++, GT1a ++++, GT1b ++, GQ1b +++, and GD1b +++), which had been negative on admission. Biopsy of the left sural nerve showed moderate reductions of large and small myelinated fibers with no inflammation, no depositions of amyloid, IgG, IgA, or IgM, and teased fiber findings revealed neither myelin ovoids nor segmental demyelination. Alternatively, melphalan at 5 mg and PSL at 32 mg were administered, with no amelioration, while serum IgA-λ monoclonal protein diminished, and IgM-λ M protein positivity was continuously observed. She frequently developed sepsis; therefore, we could no longer continue any immunosupressive therapies, but monthly IVIg administrations were given. Twelve months after admission, her neurological symptoms gradually improved and she was weaned off of mechanical ventilation. Eighteen months after admission, her muscle strength corresponded to 2 on manual muscle testing, and wheelchair transfer became possible. To the best of our knowledge, the present case is the first report of CIDP with MGUS showing an alternating immunoglobulin class.