EBV-positive inflammatory follicular dendritic cell sarcoma occurring in different organs: a case report and literature review

Abstract

Background: Epstein-Barr virus (EBV)-positive inflammatory follicular dendritic cell sarcoma (EBV+ IFDCS) represents a low-grade malignancy arising from the proliferation of follicular dendritic cells. This distinct and rare subtype, characterized by abundant lymphoplasmacytic infiltration, is closely linked to EBV infection and is seldom encountered in clinical practice.

Methods: Presented here are three cases of primary EBV+ IFDCS, occurring in the liver and spleen. This study systematically analyzed the clinical presentations, radiological features, and pathological characteristics of our cases. Additionally, we conducted a comprehensive review of the respective characteristics documented in the existing literature.

Results: We present three cases of EBV+ IFDCS, with lesions localized to the spleen (n=2) and liver (n=1). Notably, only one patient developed clinical symptoms secondary to splenic mass rupture and post-embolization sequelae, while the remaining cases were identified incidentally without associated symptomatology. All three patients underwent preoperative contrast-enhanced magnetic resonance imaging (CT) scans demonstrating solitary, well-circumscribed round masses/nodules. The two splenic lesions exhibited necrotic-cystic degeneration and one displayed a capsule, with absence of calcification in all cases. Tumor parenchyma showed mild arterial-phase enhancement and partial delayed-phase washout. The two splenic cases underwent additional magnetic resonance imaging (MRI) evaluation, revealing restricted diffusion in the solid tumor components and apparent diffusion coefficient (ADC) values comparable to the surrounding splenic parenchyma. Complete surgical excision was performed in all patients, and histopathological evaluation confirmed the diagnosis of EBV+ IFDCS through immunohistochemical analysis. As of the latest follow-up, all three patients are alive.

Conclusion: EBV+ IFDCS is a rare condition that primarily arises in the liver and spleen, with prognosis varying among patients with primary tumors in different organs. This study presents three cases of EBV+ IFDCS that occurred in diverse anatomical locations, examines their clinical, radiological, pathological features and differential diagnoses, and aims to deepen the understanding of clinicians and radiologists regarding this form of Mesenchymal dendritic cell neoplasm.

Keywords: EBV-positive inflammatory follicular dendritic cell sarcoma; Epstein-Barr virus; case report; computed tomography; magnetic resonance imaging.

Figure 1

(A): Contrast-enhanced CT reveals a well-defined, rounded splenic mass with mild enhancement of solid components, a visible capsule, absence of calcification, and features of hemorrhage and necrotic cystic degeneration. No evidence of metastatic spread was identified; (B): Contrast-enhanced MRI demonstrates a heterogeneously hypointense signal on pre-contrast T1-weighted imaging; (C): T2-weighted MRI sequences show heterogeneously intermediate-to-hyperintense signal with internal hypointense areas; (D): DWI reveals heterogeneously hyperintense signal; (E–G) (axial): Post-contrast axial scans exhibit minimal enhancement in most regions with focal enhancing areas, showing no delayed phase progression. The tumor is encapsulated and devoid of fatty components; (H) (coronal): Post-contrast coronal scan confirms the encapsulated tumor with minimal and focal enhancement; (I) (x200): Histopathological examination with hematoxylin-eosin (HE) staining displays spindle-shaped neoplastic cells arranged in a storiform pattern, featuring indistinct cellular boundaries, prominent nucleoli, and marked inflammatory infiltrate (red arrow: neoplastic cells; blue arrow: lymphocytes); (J) (x200): EBER in situ hybridization confirms nuclear positivity within tumor cells; (K) (x200): Immunohistochemical analysis reveals CD21 membranous expression in neoplastic cells; (L) (x200): Ki-67 labeling demonstrates a low proliferative index.

Figure 2

(A) Contrast-enhanced CT demonstrates a splenic space-occupying lesion (mass) exhibiting a rounded morphology with ill-defined margins. The solid components display mild contrast enhancement, while cystic necrosis and poorly-defined hemorrhage are observed. Absence of a capsule, calcification, or metastatic features is noted; (B) Pre-contrast MRI shows the lesion with peripheral isointensity and central hypointensity; (C) T2-weighted MRI demonstrates peripheral isointensity with central intermediate-to-hyperintense signal; (D) DWI) reveals peripheral hyperintensity surrounding a central hypointense region; (E–G) (axial): Post-contrast axial imaging reveals mild-to-moderate heterogeneous enhancement without evidence of encapsulation or fatty components; (H) (coronal): Post-contrast coronal imaging confirms mild-to-moderate heterogeneous enhancement without evidence of encapsulation or fatty components.

Figure 3

(A, B): Contrast-enhanced CT demonstrates an irregularly shaped, poorly demarcated space-occupying lesion within the hepatic hilar region. The lesion exhibits progressive mild-to-moderate enhancement on post-contrast phases, accompanied by internal cystic necrosis. Absence of encapsulation, calcification, hemorrhage, or metastatic features is noted; (C) (x200): Histopathological evaluation with HE staining displays neoplastic cells arranged in a storiform pattern, characterized by plump spindle-shaped morphology, indistinct cellular boundaries, prominent nucleoli, pale cytoplasm, and marked inflammatory infiltrate (red arrow: neoplastic cells; blue arrow: lymphocytes); (D) (x200): EBER in situ hybridization confirms nuclear positivity within tumor cells; (E) (x200): Immunohistochemical analysis reveals CD21 membranous expression in neoplastic cells; F (x200): Ki-67 labeling demonstrates a low proliferative index.