We discuss two cases receiving different anti-tumornecrosis-factor alpha antagonists (anti-TNF-alpha); one for psoriatic arthritis (PA) and the other for ankylosing spondylitis (AS). Due to neurological symptoms cerebral magnetic resonance imaging (MRI) was performed and cerebral lesions were detected. Our interpretations of these cerebral lesions and the resulting diagnostic and therapeutic consequences are presented in regard of data published in the medical literature.