Abstract
Follicular dendritic cell sarcoma (FDCS) is a rare malignancy with variable biological behavior. This multicenter retrospective study collected 45 cases of FDCS and 17 cases of EBV-positive inflammatory FDCS (EBV+IFDCS) and comprehensively analyzed their clinicopathological features and prognosis. The results showed intra-abdominal FDCS had a significantly higher recurrence/metastasis rate (81.3%) than extra-abdominal FDCS (26.3%, p = 0.002) and EBV+IFDCS (13.3%, p < 0.001), progression-free survival of which also showed significant differences from the extra-abdominal FDCS (p = 0.041) and EBV+IFDCS (p = 0.001), suggesting the intra-abdominal location could be an adverse prognostic factor of FDCS. Notably, this study demonstrated that 50% of intra-abdominal FDCS were associated with hyaline-vascular Castleman disease (HVCD), which was higher than that of extra-abdominal FDCS (p = 0.011) and EBV+IFDCS (p = 0.001). A morphological progression spectrum was observed from HVCD to dysplasia of FDC, and finally sarcomatous transformation, implying that HVCD might represent a precursor lesion of intra-abdominal FDCS.