滤泡树突状细胞肉瘤（FDCS）是一种罕见的低中度恶性肿瘤。目前，关于FDCS临床病程的发表数据有限，并未进行条件生存研究。因此，我们回顾性分析了来自Surveillance，Epidemiology和End Results（SEER）数据库的187例FDCS患者。在本研究中，诊断时的中位年龄为50岁，91例（48.7%）为男性。最常见的原发部位是腹腔/盆腔（82例，43.9%）。1年、3年和5年的总生存率分别为88.7%、69.0%和59.8%。5年的条件总生存率从基线的65.7%增加到5年幸存者的83.8%。3年的FDCS特异性死亡率为26.7%，其他原因导致的死亡率为3.7%。此外，诊断后的头四年内年死亡风险最高，并在第7和第8年重新增加。诊断时年龄>60岁、转移性疾病和胸腔器官中的FDCS与较短的总生存和FDCS特异性生存相关。此外，具有局部或转移性疾病的FDCS患者可以从手术治疗中获益。此外，对于局部疾病，辅助放疗或化疗并未明显改善总体生存率或FDCS特异性生存率。我们希望这些发现可以指导FDCS患者的治疗和监测策略在临床实践中的应用。

Follicular dendritic cell sarcoma (FDCS) is a rare low-intermediate grade malignant neoplasm. To date, published data on FDCS clinical courses are sparse, and no conditional survival study has been performed. Thus, we retrospectively analyzed 187 patients diagnosed with FDCS from the Surveillance, Epidemiology, and End Results (SEER) database. In this study, the median age at diagnosis was 50 years and 91 (48.7%) patients were male. The most common primary location was the abdomen/pelvis (82, 43.9%). The 1-year, 3-year, and 5-year overall survival (OS) were 88.7%, 69.0%, and 59.8%, respectively. The 5-year conditional overall survival increased from 65.7% at baseline to 83.8% in 5-year survivors. The 3-year FDCS-specific death rate was 26.7% and the rate of death from other reasons was 3.7%. In addition, the annual death hazard was the highest in the first four years after diagnosis and increased again in the 7th and 8th years. Age > 60 years at diagnosis, metastatic disease, and FDCS in thoracic organs were associated with shorter OS and FDCS-specific survival. In addition, FDCS patients, with either local or metastatic disease, could benefit from surgery therapy. In addition, adjuvant radiotherapy or chemotherapy for local disease provided no significant improvement in overall survival or FDCS-specific survival. We hope these findings may guide treatments and surveillance strategies for FDCS patients in clinical practice.