OBJECTIVE: The present study aims to explore the clinicopathological characteristics of Epstein-Barr virus (EBV)-positive inflammatory follicular dendritic cell sarcoma (IFDCS; EBV+ IFDCS).
METHODS: The case involved a 32-year-old woman who underwent surgical resection of a splenic nodule. Histological examination and immunohistochemistry were performed using cluster of differentiation (CD) markers, and in-situ hybridization was conducted to detect EBV-encoded RNA (EBER).
RESULTS: A microscopic analysis revealed neoplastic cells with various morphologies, including round, ovoid, or spindled shapes, dispersed within a prominent lymphoplasmacytic infiltrate. The tumor cells exhibited nuclear atypia, with some resembling Reed-Sternberg cells. The immunohistochemistry demonstrated focal positivity for follicular dendritic cell markers, such as CD21, CD23 and CD35, and focal negativity for other markers, including CD3, CD34, CD20, CD79a, myeloperoxidase and HMB45. Additionally, the EBER staining showed strongly positive results. The patient showed no local recurrence or metastasis during the 13-month follow-up.
CONCLUSIONS: A comprehensive understanding of EBV+IFDCS, including its clinicopathological features and immunohistochemical characteristics, is crucial for accurate diagnosis and differential diagnosis of this rare tumor.

Histiocytic, dendritic, and stromal cell lesions that occur in the spleen are challenging diagnostically, not well studied due to their rarity, and therefore somewhat controversial. New techniques for obtaining tissue samples also create challenges as splenectomy is no longer common and needle biopsy does not afford the same opportunity for examination of tissue. Characteristic primary splenic histiocytic, dendritic, and stromal cell lesions are presented in this paper with new molecular genetic findings in some entities that help differentiate these lesions from those occurring in non-splenic sites, such as soft tissue, and identify possible molecular markers for diagnosis.