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.

Sarcoma folicular de células dendríticas mediastinal: primer reporte de caso en Costa Rica / Mediastinal Follicular Dendritic Cell Sarcoma: First Case Report in Costa Rica

El sarcoma folicular de células dendríticas (SFCD) es una neoplasia maligna rara derivada de las células dendríticas foliculares. Ha sido clasificado, dadas sus características inmunohistoquímicas, como parte del grupo de los sarcomas, donde representa un porcentaje menor al 1%. Actualmente, existen menos de 1.000 reportes en la literatura a nivel mundial, lo cual plantea una dificultad no sólo diagnóstica, siendo confundido frecuentemente con neoplasias de tipo linfoide; sino también terapéutica al no existir un claro consenso sobre su manejo definitivo. Esta revisión de caso clínico describe el primer caso reportado de SFCD en Costa Rica.

Follicular dendritic cell sarcoma (SFCD) is a rare malignant neoplasm derived from follicular dendritic cells, which has been classified, given its immunohistochemical characteristics, as part of the group of sarcomas, where it represents less than 1%. Currently, there are less than 1000 reports in the literature worldwide, which generates a difficulty not only in diagnosis, being frequently confused with lymphoid type neoplasms; but also, as therapeutic as there is no clear consensus on its definitive management. This clinical case review describes the first reported case of SFCD in Costa Rica.

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.

Primary follicular dendritic cell sarcoma of the kidney - a case report of a rare tumor with emphasis on diagnostic pitfalls.

BACKGROUND: Follicular dendritic cell sarcoma (FDCS) is a rare low-grade tumor of the lymph nodes, but roughly one-third of the cases emerge from extranodal sites, posing diagnostic challenges. CASE PRESENTATION: In this report, we present the case of a 59-year-old lady who complained of renal colic. During investigation, a kidney tumor was discovered. A radical nephrectomy was performed, and histological examination identified the tumor as a sarcomatoid renal cell carcinoma. The case was then referred to a genitourinary pathologist for further evaluation. The tumor cells exhibited positive staining for CD21, CD23, somatostatin receptor 2 A, and MDM2 expression. Additionally, MDM2 gene amplification was confirmed by the FISH study. Ultimately, the tumor was diagnosed as a primary renal FDCS. The patient was placed under active oncological surveillance and did not receive any further therapy. Remarkably, after 91 months of follow-up, she remains tumor-free. CONCLUSION: This case represents a well-documented primary renal FDCS. Our aim in presenting this extremely rare tumor is to enhance awareness and highlight the importance of considering FDCS in the differential diagnosis.

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.

EBV-Positive Inflammatory Follicular Dendritic Cell Sarcoma of the Spleen: Report of an Aggressive Form With Molecular Characterization.

EBV-positive inflammatory follicular dendritic cell sarcoma (EBV+ inflammatory FDCS) is a rare neoplasm almost exclusively located in the spleen or liver. It is characterized by a proliferation of EBV-positive spindle-shaped cells bearing follicular dendritic cell markers, associated with an abundant lymphoplasmacytic infiltrate. EBV+ inflammatory FDCS is often asymptomatic or responsible for mild symptoms. It usually displays an indolent course and its prognosis is excellent after tumor removal, although relapsing and metastatic forms exist. Herein, we describe an aggressive form of splenic EBV+ inflammatory FDCS in a 79-year-old woman presenting with abdominal pain, deterioration of general health status, major inflammatory syndrome, and symptomatic hypercalcemia. A splenectomy was performed leading to a rapid improvement in her clinical condition and normalization of laboratory abnormalities. Unfortunately, her symptoms and laboratory abnormalities reappeared 4 months later. Computed tomography showed a mass in the splenectomy site and multiple liver and peritoneal nodules. Further analyses were performed on tumor tissue and showed positive phospho-ERK staining of tumoral cells indicating activation of MAPK pathway. Inactivating mutations were found on CDKN2A and NF1 genes. Subsequently, the patient's condition deteriorated rapidly. Since interleukin-6 levels were dramatically increased, tocilizumab was used but only had a transient effect on the patient's symptoms and inflammatory syndrome. Antitumor agent gemcitabine was initiated but her clinical condition continued to deteriorate and the patient died 2 weeks later. The management of aggressive forms of EBV+ inflammatory FDCS remains challenging. However, since these tumors seem to display genetic alterations, better characterization could lead to molecular targeted therapies.

Unicentric Castleman Disease: Illustration of Its Morphologic Spectrum and Review of the Differential Diagnosis.

CONTEXT.­: Unicentric Castleman disease (UCD) is a dynamic entity with a wide spectrum of morphologic findings. UCD can be further subdivided into hyaline-vascular and mixed/plasmacytic variants. Hyaline-vascular UCD has both follicular and interfollicular (stromal) changes, and occasionally these lesions show a skewed representation of either the follicular or stromal compartments. Plasmacytosis is usually minimal in the hyaline-vascular variant. The mixed/plasmacytic variant of UCD is composed of sheets of plasma cells often associated with a variable number of follicles with regressive changes. OBJECTIVE.­: To illustrate the differential diagnosis of UCD, as it is quite broad and includes lymphomas, plasma cell neoplasms, stromal neoplasms such as follicular dendritic cell sarcoma and vascular neoplasms, immunoglobulin G4-related disease, infections, and other rare lesions. An additional objective is to enhance awareness of the morphologic features of UCD in excisional and in small core-needle biopsy specimens, the latter of which may inadvertently target follicle- or stroma-rich areas, causing diagnostic challenges. DATA SOURCES.­: In this review, we provide readers a concise illustration of the morphologic spectrum of UCD that we have encountered in our practice and a brief discussion of entities in the differential diagnosis. CONCLUSIONS.­: UCD exhibits a broad spectrum of morphologic changes, and awareness of these morphologic variations is key to avoid misdiagnosis.

18 F-FDG PET/CT Versus 68 Ga-FAPI PET/CT in a Case of Isolated Nodal-Type Follicular Dendritic Cell Sarcoma.

ABSTRACT: Follicular dendritic cell sarcoma is a rare low-grade sarcoma originating from mesenchymal dendritic cells. We presented 18 F-FDG and 68 Ga-FAPI PET/CT findings in a 32-year-old woman with pathologically confirmed nodal-type follicular dendritic cell sarcoma. In this case, follicular dendritic cell sarcoma demonstrated lower uptake with FAPI than FDG.

Pancreatic follicular dendritic cell sarcoma: a case report.

BACKGROUND: Follicular dendritic cell sarcoma (FDCS) is a rare, low-to-moderate-grade malignant tumor, which occurs in the dendritic cells of the germinal center. Pancreatic FDCS (PFDCS) is extremely rare, with only a few reported cases. Presently, the etiology and pathogenesis of pancreatic FDCS are still unclear, and the clinical symptoms and signs as well as the laboratory diagnosis lack specificity. Although PFDCS presents better histological and morphological characteristics and a distinct immunophenotype, it can be easily missed and/or misdiagnosed if it occurs outside the node. Lymph node FDCS are easier to diagnose because of the rarity of fusiform cell tumors in lymph nodes. CASE DEMONSTRATION: Herein, we reported a 67-year-old female patient with upper-left abdominal pain without obvious cause and was admitted for treatment. A computed tomography (CT) scan revealed a cystic solid mass in the pancreatic tail toward the greater curvature of the stomach, with an obvious enhancement of the cyst wall in enhanced scanning. Subsequently, the patient underwent surgical resection and the resected sample was sent for pathological biopsy. According to the results, the pathology was consistent with the histological morphology and immunohistochemical characteristics of FDCS, and the Epstein-Barr virus (EBV)-encoded RNA was negative for in situ hybridization. Three months post-resection, the patient returned to the hospital for chemotherapy. This case report is aimed to improve the clinical recognition of FDCS. CONCLUSION: Pancreatic FDCS is a rare disease. Herein, we have reported a case of pancreatic FDCS and analyzed its clinical and pathological features and differential diagnosis to improve the understanding of FDCS.

Favorable response to PD-1 inhibitor plus chemotherapy as first-line treatment for metastatic follicular dendritic cell sarcoma of the spleen: a case report.

Follicular dendritic cell sarcoma (FDCS) is an uncommon low-grade malignant sarcoma. For localized FDCS, surgery is the most commonly recommended therapy option. However, there is no standard treatment protocol for metastatic FDCS. Here, we present a 68-year-old female with primary spleen FDCS who had multiple peritoneal metastases. She was treated with sintilimab (PD-1 inhibitor) plus chemotherapy (epirubicin plus ifosfamide) as first-line treatment achieving partial response (PR) and a relatively long progression-free survival (PFS) of 17 months. This case suggests that PD-1 inhibitor plus chemotherapy as first-line therapy seem to be a promising treatment option for metastatic FDCS.