Ruimiao Shang†
Shuxu Zhu
Xiaoying Tao- Department of Ultrasound, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, Zhejiang, China
Background: Follicular dendritic cell sarcoma (FDCS) is an extremely rare malignant neoplasm originating from immune follicular dendritic cells. Its inflammatory pseudotumor-like subtype (IPT-like FDCS) is even more uncommon due to morphological overlap with inflammatory pseudotumors. We report a case of splenic IPT-like FDCS and perform a systematic literature review to clarify the multimodal imaging characteristics of this rare entity.
Case presentation: A 50-year-old asymptomatic man had an incidentally detected splenic mass during routine health screening. Ultrasound showed a well-defined hypoechoic splenic lesion. Magnetic resonance imaging revealed slightly hyperintense signals on both T1- and T2-weighted images, with progressive inhomogeneous enhancement and a peripheral hypointense ring on T2-weighted sequences. The patient underwent splenectomy, and IPT-like FDCS was confirmed via histopathology and immunohistochemistry.
Conclusions: Splenic IPT-like FDCS typically presents with nonspecific or subclinical manifestations, making noninvasive imaging modalities crucial for diagnostic hint. Progressive heterogeneous enhancement and a peripheral hypointense ring on T2-weighted imaging may be valuable imaging features for identifying this rare malignancy.
Introduction
Inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) usually occurs in the liver and spleen, and to a lesser extent in the gastrointestinal tract, pancreas, and other organs (1, 2). IPT-like FDCS is more common in women, with an average age of 56.5 years (3). Because of its atypical imaging presentation, IPT-like FDCS is easily misdiagnosed as hemangioma, inflammatory pseudotumor, or other conditions. IPT-like FDCS was found for the first time in our hospital, and this article describes the discovery, diagnosis, and treatment of this disease in the context of the literature.
Case presentation
A 50-year-old male patient presented to our hospital in October 2023 due to an incidentally detected splenic lesion during a routine physical examination. The patient denied any subjective symptoms and had no relevant medical history; physical examination yielded unremarkable findings.
On the same day, ultrasonography was performed using a Mindray Resona R9TB system with an SC6-1U transducer, which revealed a mass measuring approximately 48 × 48 mm at the splenic inferior pole, with well-demarcated borders; color Doppler ultrasonography demonstrated visible intralesional blood flow signals (Figure 1). On the third day of hospitalization, magnetic resonance imaging (MRI) was performed on a Siemens Magnetom Avanto 1.5 T scanner, which revealed a splenic mass with slightly hyperintense signals on both T1-weighted and T2-weighted images, measuring approximately 57 × 54 mm. The lesion exhibited progressive heterogeneous enhancement after contrast administration (Figure 2).
Figure 1. (A) Ultrasound revealed a hypoechoic mass of approximately 48 × 48 mm in size in the lower pole of the spleen, with well-defined borders. (B) The color Doppler revealed that blood flow signals were visible within the mass.
Figure 2. (A) T1-weighted MRI revealed a mass located within the spleen, which demonstrated a slightly hyperintense signal. (B) T2-weighted MRI showed that the mass presented a slightly hyperintense signal. (C) Post-contrast MRI (arterial phase) revealed homogeneous enhancement of the mass. (D) Post-contrast MRI (portal venous phase) showed further enhancement of the mass.
On the fourth day of hospitalization, laparoscopic splenectomy was successfully performed. Intraoperatively, a round, solid tumor was identified at the splenic inferior pole; sectioning of the tumor revealed a fish-flesh-like cut surface. The patient had an uneventful postoperative recovery and was discharged smoothly. The final diagnosis of IPT-like FDCS was established based on integrated histopathological and immunohistochemical findings. Immunohistochemical staining was conducted via the EnVision method on an automated immunohistochemistry analyzer (Leica Bond-MAX), with primary antibodies sourced from Beijing Zhongshan Golden Bridge Biotechnology Co., Ltd. and Fuzhou Maixin Biotechnology Co., Ltd. Immunohistopathological results showed the following immunoreactivity profile: CD21(+), CD23(+), CD35(+), Bcl-2(−), Bcl-6(−), CD10(−), CD68(+), CD138(+), CD3(−), CD30(−), CD43(+), CD38(+), CD34(−), and Ki-67 (20% positive). In situ hybridization confirmed Epstein–Barr virus-encoded small RNA (EBER) positivity (Figure 3).
Figure 3. (A) The tumor cells were spindle-shaped and scattered in the background of chronic inflammation (HE 20×). (B) The nuclear chromatin was slightly vacuolar and some nucleoli could be seen: EBER(+), (HE 20×).
At the 1-year follow-up, the patient was contacted via telephone. He reported no physical discomfort but did not return to the hospital for further imaging or laboratory follow-up examinations.
Discussion
Follicular dendritic cell sarcoma (FDCS) is a rare mesenchymal neoplasm originating from follicular dendritic cells of the lymphoid tissue. Initially described in 1986 (4), this entity gained further recognition in 1996 when a morphologically distinct variant resembling inflammatory pseudotumor was reported, with proposed etiological links to Epstein–Barr virus (EBV) infection (5). The term “inflammatory pseudotumor-like follicular dendritic cell sarcoma” was subsequently formalized by Cheuk et al. in 2001 to characterize this clinicopathological subtype (6). Clinically, IPT-like FDCS typically follows an indolent course, and most patients are asymptomatic at initial presentation. Nonspecific symptoms such as localized pain or abdominal distension are observed in a minority of cases, often correlating with tumor size or anatomical involvement (7).
Several studies have demonstrated an association between inflammatory IPT-like FDCS and EBV, with latent membrane protein 1 detected in the majority of IPT-like FDCS cases (8). EBER in situ hybridization holds significant value in the definitive diagnosis of this condition (9). To systematically clarify the core characteristics of such cases and lay a foundation for subsequent analysis of diagnostic pitfalls, and management implications, we summarized and compared the key clinical and pathological data of reported cases in Table 1, focusing on multi-modality imaging findings [ultrasound, computed tomography (CT), and MRI], EBER status, and management strategies.
Table 1. Summary of clinical, pathological, multi-modality imaging findings, EBER status, and management strategies of reported splenic IPT-FDCS cases.
The sonographic features of splenic IPT-like FDCS may vary according to tumor size. For small lesions, the mass tend to appear as a well-circumscribed, uniformly hypoechoic nodule, with no detectable blood flow signals on color Doppler imaging. In contrast, larger lesions may exhibit heterogeneous echogenicity, accompanied by either well-defined or ill-defined margins, and intralesional blood flow signals can often be identified (10). Research focusing on the contrast-enhanced ultrasound (CEUS) manifestations of IPT-like FDCS remains relatively limited to date. In a study conducted by Xu et al., the lesion was noted to exhibit mild, rapid, heterogeneous enhancement that progressed centripetally from the periphery to the center during CEUS examination (21). For differential diagnosis, splenic hemangiomas typically present as well-circumscribed hypoechoic or hyperechoic lesions on conventional ultrasound, and their CEUS pattern is characterized by peripheral nodular enhancement—a feature that necessitates the inclusion of splenic hemangioma in the differential diagnosis of IPT-like FDCS (22).
Splenic IPT-like FDCS manifests as a hypodense lesion with either well-demarcated or indistinct borders on CT (23). Notably, the contrast enhancement patterns of IPT-like FDCS in the liver and spleen differ significantly. Hepatic tumors exhibit mild enhancement during the arterial phase, followed by gradual washout of contrast in the portal venous and delayed phases, ultimately demonstrating a density slightly lower than that of the adjacent hepatic parenchyma. In contrast, the solid components of splenic tumors display mild, persistent enhancement, while central regions with liquefactive necrosis remain non-enhancing (21).
Hepatic IPT-like FDCS may typically demonstrate hypointensity on T1-weighted image and hyperintensity on T2-weighted image. In contrast, splenic tumors more frequently exhibit isointense or hyperintensity on T1-weighted image and mild hypointensity on T2-weighted image, with heterogeneous internal signal intensity owing to fibrous scarring and vascular components. The solid portions display mild progressive enhancement, while central liquefactive or necrotic areas demonstrate no significant enhancement (11, 12). However, in our case, the tumor demonstrated a mildly hyperintense signal on T2-weighted image. This variation in T2-weighted image may be associated with the degree and distribution of inflammatory cells and proliferating capillaries within the tumor (13). In addition, a peripheral hypointense ring was visualized on T2-weighted imaging; this ring exhibited mild enhancement during the delayed phase of contrast-enhanced T1-weighted imaging. This radiological feature could potentially correlate with the vascular distribution within the tumor’s pseudocapsule.
Splenic IPT-like FDCS requires differentiation from inflammatory pseudotumor, hemangioma, and splenic lymphoma on MRI scans. Inflammatory pseudotumor of the spleen may present with slightly hypointense signals on T1-weighted image and slightly hyperintense signals on T2-weighted image, along with peripheral rim-like enhancement at arterial phase (24). Splenic lymphoma is often associated with splenomegaly and enlarged retroperitoneal lymph nodes, typically demonstrating homogeneous enhancement of the tumor parenchyma (25). Splenic hemangioma exhibits markedly hyperintense signals on T2-weighted image and shows gradual centripetal enhancement during contrast-enhanced phases (2). These differential diagnostic features are summarized in Table 2 for clearer comparison.
Table 2. Comparison of imaging and clinical characteristics of splenic IPT-like FDCS and other similar diseases.
Histologically, IPT-like FDCS shares overlapping features with inflammatory pseudotumor. Microscopically, the neoplastic cells exhibit spindle-to-oval morphology and are organized in a fascicular, whorl, or storiform pattern (26). A defining histopathological distinction from classical FDCS is the prominent mixed inflammatory infiltrate (lymphocytes, plasma cells, and histiocytes) permeating the tumor microenvironment in IPT-like FDCS. Notably, the occasional presence of binucleated or multinucleated Reed–Sternberg-like cells may create diagnostic ambiguity, necessitating differentiation from Hodgkin lymphoma (9).
Immunohistochemically, CD21, CD23, and CD35 are regarded as key markers for confirming the follicular dendritic cell lineage, a view widely recognized by most scholars (27). In contrast, inflammatory pseudotumors lack consistent expression of FDC lineage markers and are often positive for myofibroblastic markers, while classical Hodgkin lymphoma is characterized by the expression of CD30 and CD15—these immunophenotypic differences constitute the key to differential diagnosis between these entities.
Compared with FDCS, IPT-like FDCS exhibits lower invasiveness and more favorable clinical outcomes (28). This subtype typically follows an indolent disease course, and complete surgical resection remains the standard therapeutic strategy for localized lesions. Current evidence on adjuvant radiotherapy and chemotherapy remains inconclusive, as their efficacy in the management of IPT-like FDCS remains controversial (29, 30). Furthermore, emerging data suggest limited responsiveness to contemporary immunotherapeutic regimens in this tumor subtype (31). Notably, longitudinal studies reveal post-treatment recurrence and metastasis rates of 28% and 27%, respectively, highlighting the necessity of rigorous long-term surveillance (32).
Conclusion
Overall, IPT-like FDCS is an extremely rare malignant neoplasm that typically presents with nonspecific clinical manifestations. The present case provides novel insights into the multimodal imaging characteristics of this uncommon malignancy. Notably, the integration of multimodal imaging findings with pathological results is key to the accurate diagnosis of this rare neoplasm—imaging serves as a critical preoperative clue, while pathology confirms the definitive diagnosis. The radiological features of IPT-like FDCS are heterogeneous, with progressive enhancement on both CT and MRI serving as a helpful diagnostic clue for this entity. In addition, a peripheral hypointense ring on T2-weighted imaging may serve as a valuable imaging marker for the preoperative identification of IPT-like FDCS. Furthermore, EBV positivity, combined with the specific immunohistochemical profile (CD21/CD23/CD35 positivity), plays a crucial role in the differential diagnosis and definitive confirmation of the disease.
Data availability statement
The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.
Ethics statement
The studies involving humans were approved by Jinhua Central Hospital Medical Ethics Review Committee. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article. Written informed consent was obtained from the participant/patient(s) for the publication of this case report.
Author contributions
RS: Data curation, Resources, Writing – review & editing. SZ: Writing – original draft. XT: Writing – review & editing.
Funding
The author(s) declared that financial support was received for this work and/or its publication. This work is financially supported by the plan projects of the Jinhua Municipal Science and Technology, Bureau, China (Grant/Award Number: 2023C221789).
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fonc.2026.1686209/full#supplementary-material
Abbreviations
FDCS, follicular dendritic cell sarcoma; IPT-like FDCS, inflammatory pseudotumor-like follicular dendritic cell sarcoma; EBV, Epstein–Barr virus; EBER, Epstein–Barr virus-encoded small RNA; CEUS, contrast-enhanced ultrasound; CT, computed tomography.
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Keywords: case report, follicular dendritic cell sarcoma, image features, inflammatory pseudotumor, spleen
Citation: Shang R, Zhu S and Tao X (2026) Splenic inflammatory pseudotumor-like follicular dendritic cell sarcoma: a case report with imaging features and literature review. Front. Oncol. 16:1686209. doi: 10.3389/fonc.2026.1686209
Received: 18 August 2025; Accepted: 22 January 2026; Revised: 19 January 2026;
Published: 11 February 2026.
Edited by:
Hui Li, Chongqing University, ChinaReviewed by:
Jiaren Zhang, First People’s Hospital of Zunyi, ChinaMuzi Meng, Queen’s University, Canada
Copyright © 2026 Shang, Zhu and Tao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Xiaoying Tao, dHh5Nzg5ODUyQDEyNi5jb20=
†These authors have contributed equally to this work