Reversible proteinuria after adalimumab discontinuation in a patient with Crohn's disease

fluorodeoxyglucose activity in the thicken wall of AAA (Figure 1B). A renal biopsy specimen showed interstitial nephritis with patchy pattern infiltration of plasma cells (Figure 1C). Immunostaining of anti-IgG4 antibodies detected that a lot of IgG4-positive plasma cells infiltrated into the interstitium, compatible with IgG4-positive multiorgan lymphoproliferative syndrome (IgG4+MOLPS) (Figure 1D). He was treated with prednisolone (PSL) 40 mg daily. His clinical manifestations, laboratory data and imaging tests were all improved within 2 weeks. IgG4+MOLPS is a new clinical entity, characterized by hyper-IgG4 gamma-globulinaemia, IgG4+ plasma cell infiltration in involved tissue with a favourable response to steroids, and includes Mikulicz’s disease, autoimmune pancreatitis (AIP), retroperitoneal and mediastinal fibrosis, interstitial nephritis and many other inflammatory conditions affecting multiple organs [1]. Though AAA is the most common type of aneurysm, IAAA is a rare variant of AAA, which is seen in 5– 10% of all cases of AAA [2]. IAAA has some similarities to retroperitoneal fibrosis and had been previously considered to be one member of chronic periaortitis as well as idiopathic retroperitoneal fibrosis. Recently, IgG4+ IAAA has been proposed to be estimated as ‘IgG4-related periaortitis’ together with retroperitoneal fibrosis [3]. 18F-FDG uptake is caused by increased glucose utilization, observed not only in malignant cells but also in inflammatory tissue [4]. 18F-FDG PET/CT has been recently reported as being useful to diagnose and followup AIP and associated extrapancreatic lesions [4]. In the present case, steroid therapy could improve immediately the clinical manifestations of IgG4+MOLPS, such as interstitial nephritis, interstitial pneumonia and IAAA. 18F-FDG PET/CT is useful for monitoring both the disease activity of IgG4+MOLPS and the effect of steroid therapy.