Splenic Inflammatory Pseudotumor-like Follicular Dendritic Cell Sarcoma: A Case Report with Imaging Features and Comprehensive Literature Review

Background Follicular dendritic cell sarcoma (FDCS) is an exceptionally rare malignant neoplasm originating from follicular dendritic cells of the immune system. A distinct histological subtype, designated as inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS), exhibits morphological overlap with inflammatory pseudotumors and represents an even more uncommon clinical entity. We presented a case of IPT-like FDCS and conducted a systematic literature review. This case provides critical insights into the multimodal imaging characteristics for this rare malignancy. Case Presentation We present a case of a 50-year-old asymptomatic male with an incidentally detected splenic mass during routine health screening. Ultrasound showed a hypoechoic mass in spleen with well-defined borders. Magnetic resonance (MRI) revealed a mass with slightly hyperintense signals both on T1-weighted and T2-weighted images. The mass showed a progressive inhomogeneous enhancement. Finally The patient underwent splenectomy, with histopathological and immunohistochemical confirmation of IPT-like FDCS. Conclusions Splenic IPT-FDCS is characterized by nonspecific or subclinical presentations, rendering non-invasive imaging modalities crucial for diagnostic confirmation. Progressive enhancement and a arc-shaped hypointense peripheral rim observed on T2-weighted image are important imaging features of IPT-FDCS.