Cytological features of inflammatory pseudotumor-like follicular dendritic cell sarcoma of spleen: A case report.

Here, we present the first cytological report of a primary splenic inflammatory pseudotumor-like follicular dendritic cell sarcoma. The 57 year-old male was incidentally found with a 2.2 cm well-demarcated splenic nodule. A sonography guided fine needle aspiration of the lesion was performed. The cytologic smears revealed loosely cohesive fragments of oval to spindle cells in a background of prominent lymphoplasmacytic infiltration. The cells showed sparse chromatin, distinct nucleoli, syncytial cell borders, and occasional cytoplasmic processes. On the liquid-based preparation, several histiocyte-like cells with emperipolesis phenomenon were noted. Scant large atypical cells with prominent, cherry-red nucleoli were found on the cell block sections. The initial cytologic interpretation was "atypical cells cannot exclude classical Hodgkin lymphoma." The subsequent partial splenectomy showed an inflammatory pseudotumor-like follicular dendritic cell sarcoma. The tumor cells were positive for CD21, CD35, smooth muscle actin, and EBER in situ hybridization. The cytologic differential diagnoses are briefly discussed. The knowledge of this rare entity, awareness of its cytomorphology, and proper ancillary tests would be helpful for correct cytologic diagnosis. Diagn. Cytopathol. 2017;45:230-234.