EBER-negative inflammatory pseudotumor-like follicular dendritic cell sarcoma of liver: A case report.

RATIONALE: Inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) of the liver is rare. It was previously believed that Epstein-Barr virus (EBV) positivity was a necessary criterion for pathological diagnosis. However, we found that there were also cases of EBV negativity. Therefore, clinicians and pathologists are reminded that EBV positivity is not a necessary condition for diagnosis. PATIENT CONCERNS: A 70-year-old female underwent computed tomography (CT) examination for upper abdominal discomfort, which revealed the presence of a liver tumor. Follow-up revealed that the tumor had progressively increased in size. DIAGNOSIS: The final diagnosis was an IPT-like follicular cell sarcoma, based on CT, MRI, HE staining, and immunohistochemical staining. INTERVENTIONS: The patient underwent a laparoscopic left hemihepatectomy. OUTCOMES: The patient has not undergone any special treatment, such as radiotherapy and chemotherapy, and has been followed up for over 3 years without experiencing any recurrence. LESSONS: IPT-like FDCS is a rare tumor that lacks definitive criteria, and its diagnosis mainly relies on pathological findings. Previously, it was believed that being EBV-positive was an important condition for diagnosis. Primary IPT-like FDCS in the liver is even rarer, and the patient in this case tested negative for EBV. It may be necessary for pathologists to consider the role of EBV in the diagnosis of IPT-like FDCS.

Extranodal Follicular Dendritic Cell Sarcoma Presenting on the Skin.

ABSTRACT: Follicular dendritic cell sarcoma is a rare intermediate-grade malignancy characterized by a proliferation of ovoid to spindle-shaped cells with morphologic and immunophenotypic features similar to normal follicular dendritic cells. It may develop in lymph nodes or extranodal sites. Its presentation in extranodal tissues is a diagnostic challenge. It requires a high index of suspicion because follicular dendritic cell markers are not included in the routine immunohistochemical panels used for differential diagnosis. In an extensive review of the English literature, we found 3 cases of follicular dendritic cell sarcoma developing on the skin. We report a case of a primary cutaneous follicular dendritic cell sarcoma in a 28-year-old man, which presented as a 6-mm skin-colored nodule on the right forearm. We describe the morphologic and immunohistochemical features and a review of the literature.

Extranodal follicular dendritic cell sarcoma presenting as colonic mass: A diagnostic and therapeutic challenge.

Folliclular dendritic cell sarcoma (FDCS) is an extremely rare neoplasm originating from folliclular dendritic cells, both nodally and extranodally. Its primary presentation as a large colonic mass is rare and can be misdiagnosed as epithelial tumor/soft tissue tumor both clinically and through histomorphology. Due to its rarity and limited consensus guidelines about its management, it presents as a diagnostic and therapeutic challenge for pathologists and oncologists. However, accurate diagnosis is imperative due to its distinct prognostic and therapeutic implications. Herein we report, two cases of extranodal FDCS of colon with the aim of contributing to the management of this uncommon entity.

Enhanced CT Findings in a Case of Recurrent Pelvic Follicular Dendritic Cell Sarcoma.

INTRODUCTION: Follicular Dendritic Cell Sarcomas (FDCS)was first found in 1986; the specificity of the disease is its rarity, with an incidence of only 0.4%, numerous doctors for its lack of understanding, the accuracy of imaging diagnosis is not great, which is easy to delay the treatment. This article summarizes several characteristic imaging manifestations of FDCS to provide imaging physicians with an understanding of the imaging properties of this rare disease. When faced with complex cases, the radiologist can consider this disease and include it in the differential diagnosis. FDCS occurs mainly in lymph nodes, mainly in the head and neck. The main symptoms are fatigue, local pain, or painless mass. The treatment method is not uniform, but scholars agree that we should strive for the opportunity of surgery as much as possible. CASE PRESENTATION: This paper reported a case of FDCS with pelvic recurrence 3 years after surgery. The patient was suspected to have lymphoma by postoperative pathology in the local hospital, and it is recommended that the patient be reexamined regularly. A soft tissue mass was recently found again in the left pelvic cavity. After an enhanced CT examination, the radiologist was skeptical of the previous diagnosis of lymphoma. Subsequently, a needle biopsy was performed at Peking University Shougang Hospital. The pathological results rejected the prior diagnosis of lymphoma after consultation with additional hospitals, and the patient was diagnosed with FDCS. CONCLUSIONS: The imaging manifestations of FDCS lack absolute specificity, but it also has imaging characteristics, such as large areas of necrosis in the huge mass, rough mass calcification in the mass, enhanced scan showed "fast in and slow out" mode, and there were blood vessels in the tumor. FDCS mainly occurs in lymph nodes and is easily misdiagnosed as GIST, inflammatory myoblastoma, lymphoma, etc. Radiologists should continue to collect cases of this disease and include suspected cases in the differential diagnosis in clinical work.

Fibroblastic reticular cell tumor of eyelid: Rare case report and review of literature.

Fibroblastic reticular cell tumours (FRCT) originate from the fibroblastic reticular cells (FBRC) which are histiocytic cells, belonging to the dendritic cell family. These tumours are extremely rare, with only a few cases reported in literature. Histomorphologically, they resemble follicular dendritic cell sarcoma (FDCS); however, they differ immunophenotypically. Extranodal presentations are rare. We report a case of malignant FBRC tumour of the left eyelid, in a 23-year-old woman, who had presented with a recurrent swelling over left lower eyelid. Microscopy revealed an ill circumbscribed tumour composed of oval to spindle cells in storiform pattern, sprinkled with lymphocytes. Immunohistochemistry was performed and diagnosis of FRCT was offered. To the best of our knowledge, this is the first report of malignant FBRC tumour arising in the eyelid region. Here we present this extremely rare case with review of the available literature.

Clinicopathologic profile of intra-abdominal follicular dendritic cell sarcoma: A study of three cases with a literature review.

Follicular dendritic cell sarcoma (FDCS) is a rare tumor, which mainly originates from follicular dendritic cells (FDCs) in the lymph nodes. Sometimes FDCS can arise from outside the lymph nodes. FDCS is an extremely rare malignant tumor in intraperitoneal or retroperitoneal tissue. We gathered the detailed clinical data of three patients diagnosed with FDCS in the abdomen. The clinical observations and histopathologic and immunohistochemical features of FDCS were analyzed. The patients included two men and one woman aged 55 ~ 61 years old. The mesentery of the small intestine and colon was involved in case 1, spleen in case 2, and retroperitoneal tissues in case 3. Two patients presented with abdominal masses, and one presented with no obvious symptoms. Histology showed ovoid to spindle neoplastic cells arranged in fascicles and storiforms with inflammatory infiltrate as well as whorled patterns in some areas. Immunohistochemical staining was positive for CD21, CD23, CD35, and SSTR2. FDCS exhibits no characteristic clinical manifestations. Morphologically, FDCS can have overlapping features with many other entities, leading to misdiagnosis. The use of histopathology supplemented with FDC markers, such as CD21, CD23, and CD35, is useful for diagnosis and differential diagnosis.

Epstein-Barr virus-positive inflammatory follicular dendritic cell sarcoma with significant granuloma: case report and literature review.

BACKGROUND: Epstein-Barr virus-positive inflammatory follicular dendritic cell sarcoma (EBV+IFDCS) is a rare disease characterized by mild clinical symptoms and non-specific imaging findings. The diagnosis of the disease depends on pathological diagnosis. However, EBV+IFDCS has a very broad spectrum of histological morphology and immune phenotypes, and its histopathological features have not been fully described by pathologists. CASE PRESENTATION: A 59-year-old female, with no significant discomfort, was found to have a splenic mass during a routine physical examination. Microscopic examination at low magnification revealed numerous epithelioid granulomas, amidst which a substantial inflammatory response was observed. Interspersed among the dense inflammatory cells were spindle or oval-shaped cells, distributed sporadically with indistinct boundaries. Under high magnification, these spindle cells had subtle features: smooth and clear nuclear membranes, inconspicuous small nucleoli, and infrequent mitotic figures. Immunophenotypically, the spindle cells expressed CD21 and CD23, and Epstein-Barr encoding region (EBER) in situ hybridization yielded positive results. The inflammatory milieu predominantly consisted of T cells, with a minority of plasma cells expressing IgG4. The confluence of morphological and immunohistochemical findings led to the final pathological diagnosis of EBV+IFDCS in this case. CONCLUSIONS: The presentation of EBV+IFDCS with pronounced granulomatous changes is rare. This morphological variant poses a high risk of misdiagnosis, frequently leading to confusion with other granulomatous diseases. Accurate diagnosis necessitates a comprehensive analysis, integrating immunohistochemistry and in situ hybridization. The case presented here is instrumental in raising awareness and understanding of EBV+IFDCS, with the goal of reducing misdiagnoses and unrecognized cases.

[Interpretation of histiocytic/dendritic cell neoplasms and stromal-derived neoplasms of lymphoid tissues in the 5th edition of WHO classification of haematolymphoid tumors].

The 5th edition of the World Health Organization classification of hematolymphoid tumors (WHO Blue Book) is soon to be published. Significant revisions have been made in the chapters on histiocytic/dendritic cell neoplasms and stroma-derived neoplasms of lymphoid tissues, leading to the reclassification and renaming of specific diseases. This article provides a concise interpretation and summary of these updates, highlighting the differences from the fourth edition. Pertinent changes from clinical pathological diagnosis to treatment and prognosis are explored, with an emphasis on recent advancements in molecular genetics. Newly introduced disease classifications are discussed, and the section on follicular dendritic cell sarcoma contributed by the author is detailed to assist readers in quickly understanding and assimilating the new classification standards.

Extranodal follicular dendritic cell sarcoma of the tonsil: An extremely rare clinical entity.

Follicular dentritic cell sarcomatous neoplasms originate from dendritic cells contained within the lymph nodes. In extranodal location, these neoplasms, are rare clinical entities, and even more so, their location in the head-neck region is extremely rare. Only 17 cases of primary dendritic cell sarcoma of the tonsil are reported in the literature at present. Being such a rare entity, histopathological diagnosis can be complex and requires great expertise and proper immunohistochemical analysis [1]. We present a case of a 48-year-old young man diagnosed with follicular dendritic cell sarcoma of the tonsil who underwent, probably for the first time in the literature, transoral robotic surgical resection.

FDG PET/CT in Follicular Dendritic Cell Sarcoma of the Jejunum With Hepatic Metastasis.

ABSTRACT: Follicular dendritic cell sarcoma of the gastrointestinal tract is a rare malignancy. We describe contrast-enhanced CT and FDG PET/CT findings in a case of jejunal follicular dendritic cell sarcoma with hepatic metastasis. The primary jejunal tumor showed inhomogeneous enhancement on contrast-enhanced CT and intense FDG uptake on PET/CT mimicking adenocarcinoma or gastrointestinal stromal tumor. The hepatic metastatic tumor showed hypovascularity on contrast-enhanced CT and mild FDG uptake on PET/CT. This case indicates that follicular dendritic cell sarcoma should be included in the differential diagnosis of the hypermetabolic intestinal lesions.

Follicular dendritic cell sarcoma arising in the stomach and abdominal cavity: A case report.

RATIONALE: Follicular dendritic cell sarcoma (FDCS) is a rare mesenchymal tumor that typically develops in lymph nodes; it is clinically uncommon and has only occasionally been documented in cases of soft tissue, liver and spleen, and retroperitoneum; it is also extremely uncommon to develop in the stomach. PATIENT CONCERNS: A 64-year-old woman who discovered a lump in her left upper abdomen 6 months prior and was taken to the hospital due to excruciating abdominal pain. DIAGNOSIS: An abdominal computed tomography scan showed a soft tissue mass around the cardia. The immunohistochemical and postoperative histopathology results were compatible with FDCS. INTERVENTIONS: The patient underwent "radical total gastrectomy and esophagojejunostomy" (Roux-Y anastomosis). OUTCOMES: The patient recovered well 2 months after surgery. LESSONS: We report a case of FDCS occurring in the stomach and abdominal cavity, which was unique in terms of clinical location, clinical presentation, and imaging signs. This case report aims to enhance clinicians' understanding and diagnosis of FDCS in the stomach and abdominal cavity and reduce the rate of clinical misdiagnosis.

Epstein-Barr Virus-Positive Inflammatory Follicular Dendritic Cell Sarcoma Presenting as a Colonic Polyp: Report of a Case with a Literature Review.

Background: Follicular dendritic cell (FDC) sarcoma is an uncommon mesenchymal origin neoplasm derived from the abnormal proliferation and differentiation of FDCs. Epstein‒Barr virus-positive inflammatory follicular dendritic cell sarcoma (EBV+ iFDCS), which used to be known as the inflammatory pseudotumour (IPT)-like variant, occurs exclusively in the liver and spleen and has rarely been reported in the gastrointestinal tract. Case study: Here, we report a case of a 52-year-old woman with a special family history undergoing a routine physical examination. The colonoscope revealed an approximately 18 mm transverse colonic polyp, and the endoscopic polypectomy was performed. Microscopically, the excised polypoid mass was composed predominantly of inflammatory cells scattered with atypical ovoid to spindle tumor cells. Interestingly, there was a remarkable infiltration of IgG4+ cells. Immunohistochemistry showed that the tumor cells were positive for CD21, CD23 and CD35. EBV-encoded mRNA (EBER) in situ hybridization also gave positive signals. These histopathology features supported the diagnosis of EBV+ iFDCS. The patient was free of disease over 1-year follow-up. Conclusion: Identification of the potential pathogenesis sites of EBV+ iFDCS in extra-hepatosplenic regions is necessary for correct and timely diagnosis, and we consider it very meaningful to share our experience of diagnosing this tumor type. Furthermore, we summarize the clinicopathological features of EBV+ iFDCS presenting as a colon polyp after a thorough review of the literature.

18 F-FDG PET/CT in Extensive Follicular Dendritic Cell Sarcoma With Response Assessment to Chemotherapy.

ABSTRACT: Follicular dendritic cell sarcoma (FDCS) is a low-grade sarcoma of mesenchymal dendritic cell origin, and it constitutes <0.4% of soft tissue sarcomas. We report a rare case of FDCS in a 32-year-old man. 18 F-FDG PET/CT demonstrated the involvement of cervical, axillary, mediastinal, abdominal, and pelvic groups of lymph nodes and spleen. A cervical lymph node biopsy suggested FDCS. 18 F-FDG PET/CT scan done after 3 cycles of chemotherapy (CHOP regime) revealed a complete metabolic response. This case presents the rarity of extensive presentation and complete response to the CHOP regime.

Fine needle aspiration cytology of follicular dendritic cell sarcoma of the stomach masquerading as gastrointestinal stromal tumor: A case report of a unique entity with emphasis on cytomorphology.

Follicular dendritic cell sarcoma (FDCS) is a rare malignant neoplasm, postulated to arise from follicular dendritic cells, with approximately 343 reported cases. Less than 100 cases of FDCS were in the gastrointestinal tract, with only four cases described in the stomach, none of them diagnosed on fine needle aspiration (FNA) cytology. We report here the first case of FDCS of the stomach diagnosed on FNA. Our patient is a 31-year-old male who presented with several years history of intermittent abdominal pain prompting occasional emergency-room visits. Imaging showed a 10.6 cm mass arising from the stomach, concerning for gastrointestinal stromal tumor. FNA cytology was performed using five passes with a 22-gauge needle. The smears were moderately cellular consisting of sheets and large, loosely cohesive clusters of ovoid to spindle cells with indistinct cytoplasmic borders and abundant cytoplasm, peppered with numerous small mature lymphocytes. The nuclei of the tumor cells were oval with finely granular chromatin with frequent nuclear grooves, pseudoinclusions, and easily recognizable mitotic figures. The tumor cells were positive for FDCS markers (CD21, CD23, and CD35).

Cytomorphology of follicular dendritic cell sarcoma: a report of 7 cases with an emphasis on the diagnostic challenges.

BACKGROUND: Follicular dendritic cell sarcoma is a malignant neoplasm derived from germinal center follicular dendritic cells, which both share a characteristic immunophenotype (namely CD21, CD23, and CD35). Cytomorphologic descriptions are few, consisting of only 26 prior cases from 24 publications. Identification by cytologic means appears challenging as the majority of previous reports disclose an erroneous or indeterminate initial cytologic diagnosis. Herein, we present the largest cytology series to date with the aim of expanding upon this small body of literature and discuss possible factors resulting in misinterpretation. MATERIALS AND METHODS: A retrospective search was conducted from 2 academic medical centers to identify histologically confirmed cases of follicular dendritic cell sarcoma with an associated cytologic component. Clinicopathologic data were tabulated and a comparative analysis of cytomorphologic and immunohistochemical features was performed. RESULTS: Seven separate cases were identified. All cases showed cohesive tumor cells with a characteristic voluminous, ill-defined cytoplasm with interconnecting fibrillary processes and intimately admixed mature lymphocytes. Features were maintained across various cytologic preparations, including conventional smear, liquid-based cytology, and touch imprint. Unusual immunohistochemical profiles were noted in a subset of cases. CONCLUSIONS: Cytomorphology is highly conserved across cases and preparations; however, a propensity for aberrant immunoexpression may contribute to diagnostic errors. Cytomorphologic features, supported by immunohistochemistry, suggest fine-needle aspiration as a reasonable diagnostic modality. Tumors with these features should include CD21, CD23, and/or CD35 in the workup.

Follicular Dendritic Cell Sarcoma of Uterine Corpus: Report of 2 Cases.

Follicular dendritic cell sarcoma is a rare dendritic/histiocytic tumor of intermediate malignant potential, which often involves extranodal sites, most commonly the gastrointestinal tract and mediastinum with only 5 cases reported in the female genital tract. We present the clinical and pathologic features of 2 such examples arising in the uterine corpus. Both patients (63 and 72-yr old) presented with postmenopausal bleeding and underwent an endometrial biopsy diagnostic of follicular dendritic cell sarcoma that was followed by hysterectomy. The tumors were polypoid, 3.5 and 5.0 cm, and were confined to the endometrium. Microscopically, ovoid to round to spindled tumor cells with pale eosinophilic cytoplasm and vesicular nuclei were arranged predominantly in sheets with an accompanying lymphocyte-rich inflammatory infiltrate. The tumor cells were positive for CD35, CD23, D2-40 in both tumors and additionally positive for CD21 in 1 tumor, all highlighting cell bodies and processes. Patients were alive without evidence of disease at 1 and 4 years with no adjuvant treatment. These cases highlight the importance of entertaining a broad differential diagnosis in lesions with epithelioid and/or spindled morphology involving the uterus.

Challenges in the Diagnosis of Epstein-Barr Virus-positive Inflammatory Follicular Dendritic Cell Sarcoma: Extremely Wide Morphologic Spectrum and Immunophenotype.

Epstein-Barr virus (EBV)-positive inflammatory follicular dendritic cell (FDC) sarcoma (EBV + IFDCS) is a rare entity, and its histopathological characteristics have not been fully described. Here, we investigated the wide morphologic spectrum and immunophenotype of this tumor with the aim to help avoid misdiagnosis. Thirteen cases of EBV + IFDCS were retrospectively analyzed, combined with a review of 70 cases reported in the literature. The median age of patients was 49 (range, 29 to 67 y). Six patients were male and 7 were female. Most cases (92.3%, 12/13) occurred in the liver or spleen, and only 1 case affected an extra-hepatosplenic site (lung, 7.7%, 1/13). Tumors were assessed for a variety of histologic features and assigned to the following morphologic groups: classic type (53.8%, 7/13), lymphoma-like subtype (38.5%, 5/13), and hemangioma-like subtype (7.7%, 1/13). The classic type had distinct EBV-positive neoplastic cells with a fascicular or storiform growth pattern, variable lymphoplasmacytic infiltrates, and blood vessels. The lymphoma-like subtype had extremely prominent lymphoplasmacytic infiltrates (resembling marginal zone lymphoma with plasmacytoid differentiation) with singly dispersed distinct EBV-positive neoplastic cells, highlighted by in situ hybridization for EBV-encoded small RNA. The hemangioma-like subtype had extremely prominent blood vessels with hyaline and/or fibrinoid degeneration, singly dispersed distinct EBV-positive neoplastic cells, and limited lymphoplasmacytic infiltrates. Immunohistochemically, the neoplastic cells showed variable staining for FDC markers (CD21, CD35, CD23, and SSTR2) and the fibroblastic marker SMA, with the staining ranging from very focal to extensive. The number of EBV-positive neoplastic cells ranged from 80 to 400/HPF. All cases showed variable expression of PD-ligand 1 (PD-L1) (CPS: 5-90). IgG4-positive cells ranged from rare up to 100/HPF. Interestingly, 2 cases satisfied the criteria proposed in a previous study, mimicking IgG4-related disease. EBV + IFDCS is an entity with an extremely wide morphologic spectrum and immunophenotype. Awareness of the spectrum of morphologic presentations of this rare tumor, specifically the lymphoma-like subtype and hemangioma-like subtype, is important for accurate diagnosis.

Extranodal Follicular Dendritic Cell Sarcoma of the Head and Neck Region: A Clinicopathological Study of 7 Cases.

Background. Follicular dendritic cell (FDC) sarcoma is a rare neoplasm arising from follicular dendritic cells (FDCs). It can be nodal or extranodal. Histological diagnosis of extranodal FDC sarcoma in the head and neck region is challenging and a significant percentage are misdiagnosed. Objectives. To report clinicopathological features of head and neck extranodal FDC sarcoma cases and discuss differential diagnoses. Methods. Seven head and neck extranodal FDC sarcomas were retrieved and clinicopathological features were noted. Results. Two tumors each involved parapharyngeal space and tonsil while remaining cases involved the parotid, soft tissue of neck and oropharynx. Age range was 12 to 79 years (mean and median age were 40 and 44 years respectively) and there was a male predilection (6 males: 1 female). All showed spindle to ovoid cells arranged in fascicles, whorls and/or storiform pattern. Mitoses ranged from 3 to 20/mm2. All tumors expressed CD21 and CD23. Two patients died of their disease at 9 and 16 months. Both had tumors larger than 5 cm with ≥10 mitoses/mm2. Three patients were alive at 12, 44 and 184 months. Conclusions. There was a distinct male predominance in our cohort. FDC sarcoma should be included in the differential diagnosis of spindle cell extranodal neoplasms in the head and neck with a whorled growth pattern and intratumoral lymphocytes. Head and neck region tumors show similar clinicopathologic characteristics as their counterparts at other locations with potential for aggressive behavior especially in tumors greater than 5 cm in size and with high mitotic rates.

MYC and TP53 Alterations but Not MAPK Pathway Mutations Are Common Oncogenic Mechanisms in Follicular Dendritic Cell Sarcomas.

CONTEXT.­: Despite their stromal origin, follicular dendritic cells (FDCs) share many functions with hematopoietic system cells. FDC neoplasms are currently classified by the World Health Organization along with those of a histiocytic nature. However, the molecular alterations driving oncogenesis in FDC sarcomas (FDCSs) are beginning to be unveiled and do not seem to concur with those described in histiocytic neoplasms, namely MAPK pathway activation. OBJECTIVE.­: To identify molecular alterations driving tumorigenesis in FDCS. DESIGN.­: We investigated the role of MYC and TP53 in FDC-derived tumor oncogenesis and assessed comprehensively the status of the MAPK pathway in 16 FDCSs, 6 inflammatory pseudotumor (IPT)-like FDCSs, and 8 IPTs. RESULTS.­: MYC structural alterations (both amplifications and rearrangements) were identified in 5 of 14 FDCSs (35.7%), all associated with MYC overexpression. TP53 mutations were identified in 4 of 14 FDCSs (28.6%), all of which displayed intense and diffuse p53 expression. None of these alterations were identified in any IPT-like FDCSs or in IPT cases. No MAPK pathway gene alterations were identified in any of the cases studied. CONCLUSIONS.­: The presence of MYC and TP53 alterations and the lack of association with Epstein-Barr virus segregate classical FDCS from IPT-like FDCS, pointing at different oncogenic mechanisms in both entities. Our results suggest a possible oncogenic role of MYC and TP53 alterations in FDCS. The absence of MAPK pathway alterations confirms the lack of a significant role of this pathway in the oncogenesis of FDC-derived neoplasms.