A man in his 70s with neurological symptoms and progressive pain during cancer therapy

Bing-Neel syndrome is a rare neurological manifestation of Waldenström's macroglobulinaemia that can occur both before and after the diagnosis is set.

A man in his seventies with Waldenström's macroglobulinaemia under treatment with ibrutinib contacted the outpatient clinic due to bilateral pain distal to the knees. We initially suspected it was a side effect of ibrutinib and discontinued the drug. A few days later, he returned with reduced general condition, fever, shivers and a limping gait, and was hospitalised. Clinical examination revealed only pulmonary crackles. With stable low IgM, CRP > 200 mg/L and fever we suspected a serious infection and started broad-spectrum antibiotic treatment. Microbiological tests were negative, and he developed no focal symptoms of infection, but the pain increased. The symptoms had commenced with paraesthesias, and neurological examination revealed ataxia, intentional tremor, decreased sensation distal to the knees and dysdiadochokinesia. Waldenström's macroglobulinaemia was present in the central nervous system, consistent with Bing-Neel syndrome. Brain MRI illustrated pathologically thickened and enhanced meninges and thickened, wavy cauda equine roots. Lumbar puncture showed monoclonal B-cells consistent with lymphoplasmacytic lymphoma. Two weeks after admission IgM had increased from 3.21 g/L to 17.2 g/L. We restarted ibrutinib at a higher dosage, and shortly after his neurological symptoms regressed and IgM normalised.

The literature consists mainly of retrospective case reports, and there is no true consensus regarding diagnostic criteria or guidelines for treatment. We suspect Bing-Neel syndrome might be underdiagnosed and consider it important to bring awareness of the disease to clinicians.