A case of Crow-Fukase syndrome with elevated soluble interleukin-6 receptor in cerebrospinal fluid. Response to double-filtration plasmapheresis and corticosteroids.

We report the case of a 33-year-old Japanese male who presented with thrombocytosis, lower limb edema, severe polyneuropathy with elevated cerebrospinal fluid (CSF) protein level and serum IgA lambda monoclonal component, fulfilling the manifestations of Crow-Fukase syndrome. A high level of soluble interleukin-6 receptor in the CSF was also found, which fluctuated in parallel with the clinical course. Initial treatment with double-filtration plasmapheresis (DFPP) reduced the serum IgA paraprotein level with improvement of the sensory component of the polyneuropathy and decrease of soluble interleukin-6 receptor in the CSF. The remaining clinical features waned off after steroid treatment. The possible role of interleukin-6 in the pathogenesis of the Crow-Fukase syndrome and the utility of DFPP treatment are discussed.