FDG PET/CT Findings of Castleman Disease Assessed by Histologic Subtypes and Compared with Laboratory Findings

Castleman disease (CD) is a relatively rare lymphoproliferative disorder and the pathophysiology of the subtypes are incompletely understood. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) demonstrates the metabolic activity of inflammatory and tumorous conditions. The FDG uptake intensity and sites of involved lesions on FDG PET/CT were assessed by histologic subtypes, and compared to the patient's hemoglobin, platelet, albumin, and high-sensitivity C-reactive protein (hs-CRP) levels. In total, 60 PET/CT images of 44 consecutive CD patients were included: 4 (9%) unicentric and 40 (91%) multicentric; 21 (48%) hyaline vascular subtype, 16 (36%) plasma cell, and 7 (16%) mixed or unclassified. The maximum standardized uptake value (SUVmax) and tumor-to-liver (T/L) ratio of involved lymph nodes (LNs) were 5.3 ± 2.4 (range, 1.6-11.5) and 2.8 ± 1.6 (range, 1.1-9.6), respectively, with no significant difference between the histologic subtypes. Higher number of involved LN stations and presence of extra-nodal involvement on FDG PET/CT were associated with thrombocytopenia, hypoalbuminemia, and elevated hs-CRP levels (p values < 0.05). FDG-avidity was not different by histologic subtypes and did not correlate with laboratory findings. However, the extent of nodal and extra-nodal involvement as noted on FDG PET/CT was significantly associated with abnormal laboratory findings in patients with CD.