IgG4(+)MOLPS associated with inflammatory abdominal aortic aneurysm, interstitial pneumonia and interstitial nephritis.

Abstract

Sir, A 74-year-old man presented with anorexia, general fatigue, weight loss and purpura on the lower legs. Auscultation revealed trivial fine crackle. The white blood cell count was 5600/mm3, with 6.0% eosinophils. Haemoglobin was 8.5 g/dl. The C-reactive protein was 5.2 mg/dl. BUN, creatinine and uric acid were 11, 0.86 and 5.9 mg/dl, respectively. Liver enzymes were within normal limits. IgG, IgA and IgM were 6170 mg/dl, 129 mg/dl and 38 mg/ dl, respectively. IgG1, IgG2, IgG3 and IgG4 were 3470, 1460, 552 and 807 mg/dl. IgE was 1070 IU/ml. Proteinuria was 100 mg/dl (0.7 g/day), and trivial microhaematuria was observed. NAG was 23.1 U/g·Crn. CH50, C3 and C4 were <6.3 CH50/ml, 19.2 mg/dl and <2.0 mg/dl, respectively. C1q was 36.0 μg/ml. The antinuclear antibody was 1280×. Rheumatoid factor and anti-cardiolipin β2 glycoprotein-I antibody were positive. Other serological tests, including ANCA, anti-ds-DNA antibody, anti-Sm antibody and anti-RNP antibody, were all negative. Enhanced computed tomography (enhanced CT) detected interstitial pneumonia and abdominal aortic aneurysm (AAA) with a wall thickness measuring 3.2 × 3.0 cm (Figure ​(Figure1A).1A). 18F-fluorodeoxyglucose positron emission tomography-CT (18F-FDG PET/CT) demonstrated increased fluorodeoxyglucose activity in the thicken wall of AAA (Figure ​(Figure1B).1B). A renal biopsy specimen showed interstitial nephritis with patchy pattern infiltration of plasma cells (Figure ​(Figure1C).1C). Immunostaining of anti-IgG4 antibodies detected that a lot of IgG4-positive plasma cells infiltrated into the interstitium, compatible with IgG4-positive multi-organ lymphoproliferative syndrome (IgG4+MOLPS) (Figure ​(Figure1D).1D). He was treated with prednisolone (PSL) 40 mg daily. His clinical manifestations, laboratory data and imaging tests were all improved within 2 weeks. Fig. 1 Findings of enhanced CT, 18F-FDG PET/CT and renal biopsy. (A) Enhanced CT reveals wall thickness of abdominal aorta, compatible with IAAA (arrow). (B) PET-CT detects FDG uptake within thicken aortic wall, compatible with IAAA (arrow). (C) Light microscopic ... 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 follow-up 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. Conflict of interest statement. None declared.