<h3>Objective:</h3> NA <h3>Background:</h3> Iatrogenic neuroinflammation has been frequently reported in recent years owing to expanding biologic therapies for the treatment of a wide range of disorders including Psoriasis. Here we report a case of Central Nervous System (CNS) vasculitis after initiation of Risankizumab, a monoclonal antibody against Interleukin-23 (IL23) used to treat Psoriasis. <h3>Design/Methods:</h3> Case report. <h3>Results:</h3> A 29-year-old female with moderate psoriasis who was started on Risankizumab about one month prior, presented with encephalopathy and left temporal lobe focal seizures with refractory status epilepticus. Her MRI showed punctate infarcts and areas of enhancement in the left temporal lobe and leptomeninges overlying the left convexity. Extensive work up revealed increased Erythrocyte Sedimentation Rate (72 mm/hr) and positive Cardiolipin (IgM and IgG) and Beta-2 Glycoprotein (IgM and IgG) antibodies suggesting antiphospholipid syndrome (APS) for which she was started on anticoagulation. Lumbar puncture revealed normal opening pressure, glucose, protein and five nucleated cells. Oligoclonal bands, meningitis/encephalitis and autoimmune encephalitis panels were negative. Subsequent brain MRI showed new areas of ischemic lesions. Cerebral angiogram was unremarkable. Biopsy revealed focal perivascular lymphocytes (CD45 and CD3 immunohistochemical stained) infiltration in dural vessels consistent with small-vessel vasculitis. She was treated with high dose steroids with clinical improvement and subsequently planned to treat with Cyclophosphamide. Risankizumab was discontinued due to possible association. <h3>Conclusions:</h3> Iatrogenic neuroinflammation has been increasingly recognized during the new era of biological molecules and monoclonal antibodies for systemic inflammatory disorders and malignancies. Tumor necrosis factor inhibitors and immune checkpoint inhibitors are more commonly associated with neuroinflammation. To the best of our knowledge, this is the first reported case of APS and CNS vasculitis possibly associated with the initiation of IL23 inhibitor Risankizumab. Although causality cannot be established with a single case, it suggests a possible association. <b>Disclosure:</b> Dr. Cabrera Pulla has nothing to disclose. Dr. Amirjanyan has nothing to disclose. Qian Wu has nothing to disclose. Dr. Mui has nothing to disclose. Dr. Imitola has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novartis . The institution of Dr. Imitola has received research support from biogen. Dr. Imitola has a non-compensated relationship as a Board Member with National MS Society that is relevant to AAN interests or activities. Dr. Imitola has a non-compensated relationship as a Committee Member with International Society for Stem Cell Research that is relevant to AAN interests or activities. Dr. Coban has nothing to disclose.