To summarize the radiological features of follicular dendritic cell tumor of spleen (FDCS).

The clinical, radiological and pathological data of 8 patients from November 2011 to November 2017 in 5 hospitals with FDCS confirmed by pathology were retrospectively analyzed. All patients underwent CT examinations including plan and enhanced CT. Three patients underwent additional MRI and two patients underwent PET-CT examinations simultaneously. The imaging features such as location, number, shape, boundary, size, internal structure, density (or signal, ¹⁸F-fluorodeoxyglucose uptake), enhancement model and the relationship with surrounding structures were observed and compared with pathological results.

Of the 8 patients with FDCS, 7 were located in the spleen and 1 was located in the spleen of the ectopic spleen of the pancreas. Seven patients with splenic FDCS underwent splenectomy and 1 patient with pancreatic ectopic spleen FDCS underwent resection of the pancreas. Multiple lesions were detected in 1 case, while single in the others. Tumor was round or oval. The tumors were well-circumscribed and presented as expansive growth. On unenhanced CT, the tumors showed a slightly lower density, and hemorrhage and necrosis could be detected in 6 lesions. Calcification was seen in 1 case, significant necrosis, and cystic change was presented in the pancreatic ectopic spleen FDCS. The solid part presented isointensity or slightly hypointensity on T₁WI, and hyperointensity on T₂WI. Cystic necrosis areas were hypointensitive on T₁WI, and hyperointensitive on T₂WI. Spoke-like areas with hypointensity on T₁WI and hyperointensity on T₂WI were detected in the center of the solid part with the distribution among the substantial degenerative and necrotic regions. PET-CT showed that the ¹⁸F-fluorodeoxyglucose was uptaked obviously. The enhancement CT showed that at the arterial phase, the tumors were markedly enhanced and continuously enhanced at portal vein phase and balance phase. Multiple liver metastases were detected in 1 case with huge FDCS. One patient was followed up for 6 years, and gastric lymphoma was detected. The others were followed up for 6 to 53 months, there remained no transfer or recurrence.

The features of FDCS of spleen mainly manifest as solid or cystic mass with clear solitary sphenoma accompanied by scarring, calcification and hemorrhage. The enhancement mode is persistent enhancement. MRI and PET-CT help to further reflect the tumor pathological basis and biological characteristics.

Splenic neoplasms; Follicular dendritic cell sarcoma; Tomography, X-ray computed; Magnetic resonance imaging