Rituximab‐induced mild encephalopathy with a reversible splenial lesion syndrome (MERS): An adverse effect to add to the list

Abstract

Mild encephalopathy with a reversible splenial lesion syndrome (MERS) is a rare clinico‐radiological entity. Rituximab (RTX)‐induced MERS has never been described before. Herein, we report the case of a 33‐year‐old patient diagnosed since 2017, with an IgG4‐related disease (IgG4‐RD). This diagnosis was retained in the face of a prolonged fever, sicca syndrome, hepatic damage and renal pseudotumour associated to a high level of IGg4 at 2.8 g/L with suggestive renal histology. The patient was treated with corticosteroid therapy with persistence of renal impairment and nephrotic syndrome indicating RTX therapy. The patient received his first dose of RTX and presented neurological and respiratory impairments a few hours afterwards. An infectious investigation comprising a SARS CoV‐2 PCR and viral PCRs (VZV, herpes and CMV) on cerebrospinal fluid (CSF) were negative. The HBV, HCV, HIV, Parvo B19, CMV, EBV, herpes, mycoplasma and syphilis serologies as well as Legionella antigenuria were also negative. The patient had received intravenous immunoglobulins (IVIG) and methylprednisone, associated with sodium valproate with favourable outcome. The diagnosis of MERS induced by RTX was retained in our patient according to clinical and radiological features. We herein report the first case of MERS following RTX in a patient treated for IgG4‐RD.

Autoimmune glial fibrillary acidic protein astrocytopathy coexistent with reversible splenial lesion syndrome: A case report and literature review

“…It is characterized by oval, non-enhanced T2 lesions in the splenium of the corpus callosum on MRI, which can completely disappear after a variable period of time ( 3 ). This syndrome was related to a variety of factors including antiepileptic drugs, infections, hypoglycemia, hyperglycemia, and electrolyte imbalance ( 4 , 5 ). Recently, a potential association between autoimmune processes and RESLES has been documented in cases such as N-methyl-D-aspartate receptor encephalitis ( 6 ), autoantibodies against voltage-gated potassium channels ( 7 ), autoimmune thyroid disease ( 8 ), and so on.…”

“…Reversible splenial lesion syndrome (RESLES) is a transient clinical-imaging syndrome characterized by the presence of a focal lesion often involving the corpus callosum ( 3 ). RESLES was first described to be triggered by antiepileptic drugs, and then it has been reported to be secondary to a variety of factors, including infection, metabolic disorders, and autoimmune diseases ( 4 , 5 ).…”