Severe subacute onset sensorimotor polyneuropathy associated with brentuximab vedotin treatment for refractory classical Hodgkin's lymphoma.

A man in his 30s with a history of refractory classical Hodgkin's lymphoma presented with subacute onset asymmetric sensory disturbance, and severe weakness affecting his right more than left hand. Symptom onset was 18 weeks after commencing brentuximab vedotin (BV) treatment, an anti-CD30 antibody drug-conjugate for relapsed/refractory classical Hodgkin's lymphoma. Symptoms progressed to his lower limbs with distal sensory loss, gait imbalance, bilateral foot drop and mild proximal leg weakness. He was globally areflexic. Neurophysiology revealed a mildly asymmetric, non-length dependent, motor >sensory polyradiculoneuropathy, with mixed axonal and demyelinating features. Extensive laboratory work-up, lumbar puncture and MRI of the brachial plexus, brain, spine and chest were unremarkable. Treatment with plasma exchange, followed by intravenous immunoglobulin, resulted in objective clinical improvement 4 weeks after. BV is a potent antimicrotubule agent, thus well known to cause a length-dependent sensory axonal polyneuropathy. Demyelinating polyneuropathy, with more prominent motor involvement, in association with BV is much rarer.