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Abstract

Follicular dendritic cells sarcoma (FDC sarcoma) are mesenchymal-derived dendritic cells located in B-follicles, where they play a pivotal role in triggering and maintaining B-cell adaptive immune response. It is an uncommon tumor with few reported cases. Using pathological tests, we investigated the computed tomography (CT) appearance, positron emission tomography-computed tomography (PET-CT), and pathological findings in a 43-year-old woman diagnosed with mediastinal FDC sarcoma which usually overlaps with lymphoma. Previous literature reports on FDC sarcoma were reviewed. FDC sarcoma should be considered in asymptomatic patients with mediastinal lymph node lesions with a diameter of more than 1cm and appears as an illdefined mass with an arborising pattern of necrosis. The complement receptor CD21(+) is an immunohistochemically specific marker for determining the pathological diagnosis of FDC sarcoma. This case report aims to highlight imaging features to facilitate this rare entity's diagnosis and treatment options.