Fig. 5

A 37-year-old male patient with inflammatory pseudotumor-like follicular dendritic cell sarcoma of the spleen. a The mass shows a slight hyperintensity on the T1-weighted image sequence. b On the T2-weighted image sequence, the tumor shows a slightly hypointense signal, and its edge displays a hypointense annular signal representing the pseudocapsule. c The mass shows a slightly hyperintense signal on diffusion-weighted imaging. d–g The contrast enhancement of the mass is mild in each phase, and the pseudocapsule shows delayed enhancement. h On histopathological examination, the tumor (black star) is surrounded by dense fibrous tissue (black arrow; hematoxylin and eosin, ×100). i Macroscopic examination showing a grayish-white tumor with uniform texture and clear boundaries. j CD21 is diffusely positive. k Epstein–Barr virus is detected in almost all of the tumor cells with positive dark staining of their nuclei