%0 Case Reports
%T Typical Bone Scintigraphy Presentation of Erdheim-Chester Disease in a Patient Diagnosed With IgG4-Related Disease.
%A François C
%A Rousselin C
%A Quemeneur T
%A Demailly F
%A Collet G
%A Fagart A
%J Clin Nucl Med
%V 49
%N 4
%D 2024 Apr 1
%M 38427961
%F 10.782
%R 10.1097/RLU.0000000000005098
%X <B>UNASSIGNED: </B>A 50-year-old woman presented a dry syndrome, joint pain, inflammatory syndrome, polyclonal hypergammaglobulinemia, and tubulointerstitial nephritis. Imaging studies (including FDG PET/CT) revealed infrarenal retroperitoneal fibrosis with periaortitis and hypermetabolic osteosclerotic lesions. Bone scintigraphy demonstrated intense uptake in the femoral, tibial, and radial regions, suggestive of non-Langerhans histiocytosis, specifically Erdheim-Chester disease. A bone biopsy confirmed the presence of IgG4-positive plasma cells but no histiocytes. The patient received corticosteroid therapy followed by rituximab, resulting in a complete response. This case suggests an atypical manifestation of bone lesions in IgG4-related disease, emphasizing the diagnostic challenge between IgG4-related disease and Erdheim-Chester disease.