Granulomatous splenic mass with necrosis revealing an EBV-positive inflammatory follicular dendritic cell sarcoma.

Epstein-Barr virus-positive inflammatory follicular dendritic cell sarcoma is a variant of follicular dendritic cell neoplasm most often arising in the liver or spleen. Two histological patterns can be identified in this variant, namely a granulomatous and an eosinophil-rich one. We present the case of a 69-year-old woman with a splenic mass. After being removed, the mass was gray-whitish with an area of necrosis. Histology showed a diffuse distribution of epithelioid granulomas in a background of a dense lymphoplasmacytic infiltrate. Rare atypical cells EBV+ and CD21+ were present in the intergranulomatous areas. Differential diagnosis for the granulomatous type EBV+ inflammatory follicular dendritic cell sarcoma includes infection, sarcoidosis, inflammatory myofibroblastic tumor, T cell lymphoma and vasculitis. The origin of this neoplasm is the follicular dendritic cell, and, due to its similarities with a myofibroblast, differential diagnosis can be challenging. Immunohistochemistry for dendritic markers and in situ hybridization for EBER remain diagnostic keys.