Peculiar Cytological Cerebrospinal Fluid Pattern in a Case of Encephalomyelitis During Anti-Tumor Necrosis Factor-α Therapy

INTRODUCTION Tumor necrosis factor-α (TNF-α) blocking agents may be associated with neurological adverse events, including demyelinating syndromes, that can be difficult to differentiate from multiple sclerosis (MS) and clinically isolated syndrome (CIS) as neither the clinical nor laboratory distinctive features have been reported. Usually clinicians mainly examine the diagnostic value of immunoglobulin G oligoclonal bands underestimating the value of other cerebrospinal fluid (CSF) parameters (such as CSF cytology). CASE REPORT We present a case of a patient who acutely developed mild pyramidal and sensory impairment of lower limbs and urinary hesitancy during treatment with adalimumab, a monoclonal antibody to TNF-α, for psoriatic arthritis. Magnetic resonance imaging demonstrated a widespread area of hyperintense signal extending from C5 to D8 level in T2-weighted images. Two consecutive CSF examinations showed an intense activation of monocyte/macrophage lineage (88% and 90%, respectively) with some giant and binucleated cells that notably decreased five months after TNF-α blocker cessation. We compared the results of CSF examinations of our patient with CSF results of 20 patients with MS and 20 patients with CIS that demonstrated activation of both lymphocytic and monocytic lineage (MS: 48% and 52%, respectively, CIS: 54.5% and 43.5%, respectively) that were very different from the findings in adalimumab-related encephalomyelitis in acute phase (11% and 89%, respectively). CSF cytology in two patients with neuromyelitis optica during the relapse (n = 3) showed minor monocyte/macrophage activation (9%) and an increased number of granulocytes (77%). CONCLUSION Prominent activation of monocyte/macrophage lineage with some binucleated giant cells in CSF could be induced by anti-TNF-α treatment. The peculiar CSF pattern, never found in MS, CIS, and NMO, can help in differential diagnosis and stresses the importance of careful CSF cytology evaluation in the course of demyelinating diseases.