AB1298 AL-AMYLOIDOSIS MIMICKING IgG4-RELATED DISEASE

Abstract

BackgroundHematological diseases such as multiple myeloma (MM) and POEMS-syndrome can be accompanied by high serum IgG4 level and thus mimic an IgG4-related disease (IgG4-RD) [1, 2]. However, there are no descriptions of AL-amyloidosis with increased secretion of IgG4 in the literature.Objectivesto present a clinical case of AL-amyloidosis mimicking IgG4-RD.MethodsAt the age of 42, patient S. developed nasal congestion, and 2 years later bilateral symmetrical swelling of submandibular salivary glands developed. Chest CT scan revealed hydrothorax and pericarditis, interstitial changes in both lungs and intrathoracic lymphadenopathy. According to blood tests, ANF, RF and CRP were within normal values, an increase in the serum IgG4 (32.9 g/l) and IgG (34.1 g/l) levels was detected, and the patient was admitted to our clinic with suspicion of IgG4-RD.ResultsOn examination, we noticed a symmetrical enlargement of submandibular salivary glands and macroglossia. The patient also complained of tingling in the fingers, we performed electroneuromyography and revealed bilateral carpal tunnel syndrome. According to the immunofixation of blood and urine proteins, IgG-lambda paraproteinemia (18,3 g/l) and a trace amount of Bence-Jones-lambda protein in the urine were detected. AL-amyloidosis was suspected and a biopsy of the submandibular salivary gland was performed, followed by Congo red staining and darkfield microscopy that confirmed amyloidosis (Figure 1). There were no signs of IgG4-RD (storiform fibrosis or obliterative phlebitis) in the biopsy specimens. Echocardiography revealed thickening of the interventricular septum and hypertrophy of the ventricular myocardium. MM and other malignancies were excluded on the basis of bone marrow trephine biopsy and PET-CT (also revealed severe hepatomegaly). The diagnosis of IgG4-secreting AL-amyloidosis affecting salivary glands, tongue, heart, lungs, liver, nervous system was made and polychemotherapy was started, the patient’s further life remained unknown.Figure 1.Congo red staining and darkfield microscopy demonstrating amyloid deposits.ConclusionAL-amyloidosis can be accompanied by high serum IgG4 level and mimic IgG4-RD. The serum level of IgG4 should not be used as a criterion for IgG4-RD, and in all cases of suspected IgG4-RD the diagnosis should be confirmed morphologically.