Follicular Dendritic Cell Sarcoma

Case report: Splenic inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS): a trial of immunotherapy and review of the literature

Inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) is a rare malignancy with fewer than 150 cases in the literature. IPT-like FDCS follows an indolent course with most cases definitively managed with surgical resection. We present a case of IPT-like FDCS with multiple recurrences with a trial of immunotherapy. The patient initially presented with splenic involvement requiring splenectomy, subsequently recurring in the liver requiring hepatic resections. Afterwards, there was recurrence with pelvic/small bowel involvement for which treatment was trialed with ipilimumab and nivolumab. The patient progressed despite dual immune checkpoint inhibitor therapy requiring a small bowel resection. To date, this is the first case of immunotherapy use in IPT-like FDCS. Therefore, more evidence is needed to support additional treatments in recurrent IPT-like FDCS after resection.

Apatinib manifests an unexpectedly favorable outcome in the management of axillary lymph node follicular dendritic cell sarcoma: a case report

We present a case of follicular dendritic cell sarcoma in the axillary lymph node, which unexpectedly showed favorable outcomes after the application of apatinib. Follicular Dendritic Cell Sarcoma (FDCS) exhibits a rare incidence and an unclear pathogenic mechanism, contributing to the limited breakthroughs in its treatment to date within the medical field. The current mainstream therapeutic approaches include surgery, CHOP(cyclophosphamide, doxorubicin, vincristine, prednisone), ICE(ifosfamide, carboplatin, etoposide), ABVD(doxorubicin, bleomycin, vinblastine, dacarbazine), and immune checkpoint inhibitors. A 38-year-old male patient was admitted to the hospital due to a lump in the right axilla and underwent surgical treatment. Postoperative pathology confirmed the diagnosis of follicular dendritic cell sarcoma. Two months post-surgery, he faced a recurrence, prompting a subsequent surgical intervention complemented by tumor radiofrequency ablation. Despite these interventions, the treatment response was suboptimal. Subsequently, the patient was treated with the CHOP regimen, but after two cycles, he developed bone metastasis. Due to the patient's limited financial resources and refusal of immunotherapy, we switched to a regimen of gemcitabine and docetaxel, but the disease progressed again after two cycles. A one-cycle trial of albumin-bound paclitaxel yielded unsatisfactory results. Ultimately, the patient was treated with Apatinib, achieving a 10-month progression-free survival. Due to the patient's limited financial circumstances, we, in the absence of guideline recommendations and evidence from evidence-based medicine, achieved a 10-month progression-free survival (PFS) solely based on experiential use of the anti-angiogenic drug, Apatinib. The purpose of this case report is to provide additional therapeutic options for FDCS treatment and to pave the way for exploring the mechanism of action of Apatinib in FDCS.

Rare co-occurrence of tonsillar follicular dendritic cell sarcoma and schizophrenia: A comprehensive study

This study investigated the infrequent occurrence of tonsillar follicular dendritic cell sarcoma (FDCS) co-existing with schizophrenia, presenting a comprehensive examination of clinical, pathological, and literature aspects. A systematic literature review was conducted, focusing on articles related to "schizophrenia" and "sarcoma," with in-depth analysis of included case reports. Clinical data, pathological findings, and patient follow-up information were collected and synthesized. The study detailed a rare case of FDCS in the tonsil concurrent with schizophrenia, providing insights into diagnosis, treatment, and follow-up. A literature review of combined FDCS in the tonsil and schizophrenia cases highlighted their clinical and pathological characteristics. Eight case reports encompassing 11 patients diagnosed with sarcoma and schizophrenia were included. Surgical resection was the preferred primary treatment, while chemotherapy was suggested for recurrences. Instances of co-occurring FDCS and schizophrenia were exceptionally limited, with tonsillar FDCS being particularly uncommon. The coexistence of tonsillar FDCS and schizophrenia was an exceptionally rare condition, posing diagnostic and therapeutic challenges. This study contributed valuable insights into clinical and pathological practice through a systematic review, underscoring the significance of early diagnosis and comprehensive management.

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.

Case report: EBV-positive epithelioid follicular dendritic cell sarcoma with CD30 expression: a highly challenging diagnosis

Introduction

Follicular dendritic cell sarcoma (FDCS) is a rare tumor entity with a wide range of anatomical sites and strong heterogeneity in morphology and immunohistochemistry, making it highly susceptible to misdiagnosis. There are two types of FDCS: conventional FDCS and EBV+ inflammatory FDCS. It is currently suggested that the former has nothing to do with EBV infection. Moreover, they have distinctively different clinicopathological characteristics.

Case description

A 69-year-old male patient was admitted to our hospital after 4 months of progressive enlargement of the neck mass. Positron emission tomography/computed tomography (PET/CT) examination showed multiple enlarged lymph nodes in the body. After cervical lymph node excision and biopsy, it was found that the tumor cells were epithelioid and diffusely expressed EBER and CD30. It was initially diagnosed as poorly differentiated cancer and lymphoma. In subsequent differential diagnosis, we found that it strongly stained CD21 and CD23, which was approved the diagnosis of EBV+ FDCS.

Conclusion

Epithelioid FDCS is very rare. EBV-positive FDCS with abnormal expression of CD30 has not been reported. Whether EBV also plays an important role in conventional FDCS requires more cases to be verified. Our case provides valuable research clues for further understanding the pathological characteristics of this tumor entity.

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.

Pitfalls in Lymph Node Fine Needle Aspiration Cytology

BACKGROUND

Fine needle aspiration cytology (FNAC) is an accurate, minimally invasive, and cost-effective biopsy method for enlarged lymph nodes. While the role of lymph node FNAC in the diagnosis of infectious or reactive conditions and metastatic malignancy is unquestioned, differing views still exist on its role in the diagnosis of lymphoma. Nevertheless, regardless of the practice setting, pitfalls and potential for error exist, and it is incumbent upon the pathologist to be aware of these pitfalls, as this is the first line of defence against errors.

SUMMARY

This discussion will focus on potential interpretational errors, specifically highlighting scenarios leading to false-negative and false-positive diagnosis and errors in tumour classification, with an emphasis on cytomorphology. Potential entities that may fly below the radar of the pathologist - so-called off-radar entities - are also discussed, as a reminder to consider broad differentials in cases with unusual morphologic features. Some reasons for false-negative diagnoses include low-grade lymphomas that mimic a mixed, polymorphous reactive lymphoid population or aspirates with a paucity of lesional cells, through either sampling error or the intrinsic nature of the entity, e.g., nodular lymphocyte predominant Hodgkin lymphoma. Some of the potential causes of false-positive diagnoses that are discussed include viral-associated lymphadenopathy, Kikuchi-Fujimoto lymphadenitis, or benign adnexal lesions mimicking metastatic malignancy. Errors in tumour classification covered include metastatic carcinoma, sarcoma, melanoma, and lymphoma mimicking each other, and Hodgkin lymphoma and its mimics. Finally, less common entities such as follicular dendritic cell sarcoma and others are briefly mentioned, to remind us of conditions that may slip under our diagnostic radar.

KEY MESSAGES

A systematic review of diagnostic pitfalls and traps is elucidated here, with some tips to avoid these traps. The triple approach to the diagnostic workup is emphasised, which includes rigorous clinicopathologic correlation, attention to cytomorphology, and judicious application of ancillary tests.

Progressive abdominal pain with acute exacerbation due to retroperitoneal follicular dendritic cell sarcoma: a case report with targeted genomic sequencing analysis

BACKGROUND

Follicular dendritic cell sarcoma (FDCS) is a rare malignancy that arises from follicular dendritic cells and typically presents as a slow-growing painless mass without specific symptoms. Here we report an unusual case of a 55-year-old female with retroperitoneal FDCS who presented with progressive abdominal pain onset and acute exacerbation.

METHODS

On CTA, a middle-upper abdominal mass (58*40 mm) was shown with multiple enlarged lymph nodes. After en-bloc resection of the tumor, the patient recovered completely from her symptoms and was discharged without complication. One month later, the patient returned for follow-up and the relevant tests were completed.

RESULTS

In this case, CA724 elevated significantly and seemed to be associated with tumor progression. The results of positron emission tomography/computed tomography (PET/CT) and radiological examinations, including magnetic resonance imaging (MRI) and computed tomography angiography (CTA), were discussed to improve our understanding of diagnostic tools on FDCS. Targeted genomic sequencing analysis revealed three novel gene mutations, EPHA3 (nonsense mutation), DDR2 (SNV), and BIRC3 (InDel).

CONCLUSION

We reported an unusual case of retroperitoneal FDCS with acute exacerbated abdominal pain. The interpretations of CA724, PET/CT, as well as imaging results deserve further investigation in FDCS. Genomic sequencing revealed three novel gene mutations in FDCS, including EPHA3 (nonsense mutation), DDR2 (SNV), and BIRC3 (InDel).

Survival analysis in patients with follicular dendritic cell sarcoma: a population-based study

Follicular dendritic cell sarcoma (FDCS) is a rare low-intermediate grade malignant neoplasm. To date, published data on FDCS clinical courses are sparse, and no conditional survival study has been performed. Thus, we retrospectively analyzed 187 patients diagnosed with FDCS from the Surveillance, Epidemiology, and End Results (SEER) database. In this study, the median age at diagnosis was 50 years and 91 (48.7%) patients were male. The most common primary location was the abdomen/pelvis (82, 43.9%). The 1-year, 3-year, and 5-year overall survival (OS) were 88.7%, 69.0%, and 59.8%, respectively. The 5-year conditional overall survival increased from 65.7% at baseline to 83.8% in 5-year survivors. The 3-year FDCS-specific death rate was 26.7% and the rate of death from other reasons was 3.7%. In addition, the annual death hazard was the highest in the first four years after diagnosis and increased again in the 7th and 8th years. Age > 60 years at diagnosis, metastatic disease, and FDCS in thoracic organs were associated with shorter OS and FDCS-specific survival. In addition, FDCS patients, with either local or metastatic disease, could benefit from surgery therapy. In addition, adjuvant radiotherapy or chemotherapy for local disease provided no significant improvement in overall survival or FDCS-specific survival. We hope these findings may guide treatments and surveillance strategies for FDCS patients in clinical practice.

Extranodal Mesenteric Follicular Dendritic Cell Sarcoma Expressing Keratin Antigens: What Pitfalls Initiate Diagnostic Clues

Extranodal follicular dendritic cell sarcomas are infrequent diagnostically challenging tumors. Because of their rarity, heterogeneous histomorphologic features and variable histologic grades a significant number of extranodal lesions are prone to be misdiagnosed. Even though they have a characteristic immunoprofile, expression of a range of nonspecific markers is well documented. Even though they are typically negative for keratins, few authors have reported lesions expressing keratin. Keratin expressing tumors are more likely to be misinterpreted by pathologists further deterring their inclusion in the differential diagnosis. We report an intraabdominal mesenteric follicular dendritic cell sarcoma in a 44-year-old male that immunophenotypically expressed keratin antigens. The lesion showed a high-grade pleomorphic epithelioid appearance and the initial differential diagnosis included lymphoma, sarcomas, melanoma, and carcinomas. Follicular dendritic cell sarcoma was not considered. Expression of epithelial membrane antigen and keratin further deterred the diagnosis which was reached only after extensive use of immunomarkers. The tumor cells expressed CD21, CD23, and D2-40. Morphologically, the tumor showed some thymoma-like features with occasional TDT-expressing background T-lymphocytes. These features were hints to reconsider our differential diagnosis to include follicular dendritic cell tumors. Awareness of this aberrant staining of epithelial immunomarkers and attention to certain clues should encourage pathologists to consider this entity. Speculative assumptions may explain this unusual keratin expression in some lesions. The histomorphologic and immunohistochemical heterogeneity may suggest different variants and grades of follicular dendritic cell sarcomas. The prevalence, importance, and histogenesis of keratin expression in follicular dendritic cell sarcomas warrant further studies.

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.

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.

Case report: Hepatic inflammatory pseudotumor-like follicular dendritic cell sarcoma: a rare case and review of the literature

Inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) is a rare subtype of follicular dendritic cell sarcoma (FDCS) that primarily occurs in the liver and spleen. The etiology of IPT-like FDCS is unknown, and it has nonspecific clinical manifestations, imaging performance and laboratory test results. Recently, a patient with IPT-like FDCS was admitted to our hospital because of abdominal distension and anemia. Over the past 3 years, the patient has been followed up after a liver mass was found in a physical examination. The lesion gradually enlarged and caused compression symptoms. In November 2022, a tumor with a diameter of approximately 20 cm was found in the right posterior lobe of the liver after abdominal enhanced Magnetic resonance imaging (MRI) in our hospital. Liver tumor biopsy before the operation revealed a large number of hyperplastic plasma cells and a small number of spindle cells, and the spindle cells were atypical. After a complete examination, the patient underwent liver resection. Pathology after surgery confirmed liver IPT-like FDCS.

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.

Mediastinal Follicular Dendritic Cell Sarcoma With Underlying Sjogren's Syndrome

Follicular dendritic cells help advance B-Cells in becoming memory B-Cells or antibody-producing plasma cells in the light zone, or undergo additional affinity maturation in the dark zone. Follicular dendritic cell sarcoma (FDCS) is an extremely rare soft tissue malignancy derived from follicular dendritic cells. Autoimmune disease increases the risks for the development of hematological malignancies. To the best of our knowledge, there are few cases of FDCS development in the setting of underlying Sjogren's syndrome (SS). Therefore, in this report, we present a novel case of FDCS associated with new-onset SS. In SS, the follicular dendritic cells are organized within germinal centers within the glands it infiltrates and is involved in B-Cell development. Because FDCS is derived from follicular dendritic cells, our report postulates that the unregulated follicular dendritic cell proliferation that may occur in SS could increase the risk for FDCS. Due to this possible connection observed in our patient, we highlight FDCS as a differential diagnosis when considering soft tissue cancers. We urge additional research to outline and explore the possible pathologic link between SS and FDCS.

Thoracic follicular dendritic cell sarcoma - an outlandish presentation of a rare tumour with review of literature

Follicular dendritic cell sarcoma is a rare low grade malignant neoplasm that arises from follicular dendritic cells in lymphoid tissue germinal centres and accounts for 0.4% of all soft tissue sarcomas. It is extremely rare to have pulmonary follicular dendritic cell sarcoma with endobronchial extension and as an anterior mediastinal mass with mediastinal lymph node involvement. We present the case of a 34-year-old male non-smoker who had been experiencing chest pain for three months. A lobulated left peri-hilar mass with endobronchial spread into the left main bronchus and mediastinal lymphadenopathy was identified on a chest CT. The bronchoscope-guided cryobiopsy of the endobronchial mass was inconclusive. After a thorough multidisciplinary discussion, the patient underwent left sided pneumonectomy, mediastinal mass resection, and systematic lymph node dissection. Histologic examination using immunohistochemistry revealed follicular dendritic cell sarcoma.

Promising clinical outcome after body gamma knife radiotherapy for mediastinal follicular dendritic cell sarcoma with thoracic spine invasion and iliac metastasis: A case report and literature review

Background

Follicular dendritic cell sarcoma (FDCS) is a rare type of intermediate grade tumor. Mediastinal FDCS with spinal invasion has not been well described. The treatment options include surgical resection and radiation therapy. The body gamma knife is a stereotactic body radiotherapy (SBRT) technology that is widely used in China. The pathological evaluation of a bone lesion after a body gamma knife procedure has not been reported. Here, we report a case of a patient with FDCS with thoracic spine invasion and iliac metastasis treated with surgery and body gamma knife.

Case summary

A 36-year-old male patient was hospitalized at Zhongshan Hospital, Fudan University, due to a gradually aggravated pain on the lateral side of the left scapula for 6 months. Imaging examination showed neoplastic lesions on the left side of C7-T2 invading the vertebral body of T1, T2, and caput costae of the second rib and suspected metastasis in the left ilium. FDCS was diagnosed after performing a computed tomography (CT)-guided core needle biopsy, and the thoracic lesion was surgically resected. The body gamma knife was used as an adjuvant radiotherapy for the thoracic lesion and a primary therapy for the left ilium lesion. Iliac bone lesion resection was performed at Zhongshan Hospital, Fudan University, 10 weeks after RT. Compared with the biopsy report, the body gamma knife treatment resulted in a pathological complete response (PCR). The magnetic resonance imaging (MRI) examinations showed stable disease of the thoracic lesion after body gamma knife radiosurgery.

Conclusion

This case report describes the treatment of mediastinal FDCS with thoracic spinal invasion and iliac metastasis. The promising outcome suggests that separation surgery is an effective treatment option for mediastinal FDCS with spinal column invasion. It also demonstrates the application prospects of the body gamma knife treatment in malignant lesions of the axial bones.

Follicular Dendritic Cell Sarcoma in a Patient With Adolescent-Onset Crohn's Disease Exposed to Multiple Immunomodulator and Biologic Therapies

Children and adolescents with inflammatory bowel disease are often treated with immunomodulators (thiopurines, methotrexate) and biologics (anti-TNF, anti-integrin) for extended periods despite concerns about long-term safety. Here, we report a case of follicular dendritic cell sarcoma, a very rare malignancy, and the first reported presentation in a patient with inflammatory bowel disease exposed to infliximab, methotrexate, and vedolizumab. We review the key clinical features and diagnostic factors of this malignancy. The pathogenesis of follicular dendritic cell sarcoma is largely unknown, however, knock out of B-cell TNF in mice has been related to follicular dendritic cell dysregulation through its impact on NF-κB pathways and CXCL13 chemokines. It is unknown whether any relationship exists between this patient's diagnosis of Crohn's disease and therapeutic exposures to this rare malignancy. We document this case in the literature to raise awareness among other clinicians who may observe a similar case.

Follicular dendritic cell sarcoma of the nasopharynx: a case report and literature review

Follicular dendritic cell sarcoma (FDCS) of the nasopharynx is a rare malignant tumor that has been described in only a few case reports, and its differential diagnoses include diverse clinicopathologic entities. FDCS is often initially misdiagnosed, especially when examining small biopsy specimens. We herein report a case of FDCS arising in the nasopharynx that was initially misdiagnosed as a nerve sheath tumor. A 44-year-old woman presented with persistent obstruction of the left nasal cavity and underwent an excisional biopsy. The specimen demonstrated morphologic and immunohistochemical features of FDCS. In situ hybridization for Epstein–Barr virus-encoded RNA was negative. The patient was treated with chemotherapy and radiotherapy. The sarcoma recurred near the original site more than 3 years after the initial treatment and was completely resected. At the time of this writing, the patient had remained disease-free for 1 year after resection. This case is being reported to improve the clinical recognition of FDCS.

A rare case of follicular dendritic sarcoma of the vagina

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Follicular dendritic cell sarcoma of the vagina is a rare tumor.

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Follicular dendritic cell sarcoma has characteristic clinicopathologic findings.

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Awareness of follicular dendritic cell sarcoma can aide in diagnosis.

Follicular dendritic sarcoma of the vagina is an exceptionally rare malignancy. Here, we present a reproductive-aged female with no pertinent past medical history who initially presented with a protruding vaginal mass. Pathology from initial excision was consistent with follicular dendritic sarcoma of the vagina. This was ultimately treated with wide radical resection of the mass leading to iatrogenic vaginal stenosis.

Castleman Disease with MDM2/CDK4 Protein Expression: a Potential Mimic of Inflammatory Variant of Liposarcoma with Significant Consequences

Castleman disease is a rare benign lymphoproliferative disorder that includes a spectrum of distinct histopathological entities. The differential diagnosis of Castleman disease is broad and includes lymphomas, HIV-related lymphadenopathy, autoimmune disorders, and inflammatory liposarcoma. When Castleman disease occurs in the retroperitoneum, the distinction from the inflammatory variant of well-differentiated liposarcoma can be very challenging in small biopsies. Herein we report a case of Castleman disease that presented as a retroperitoneal mass and expressed MDM2 and CDK4 by immunohistochemistry. To our knowledge, this is the first report of Castleman disease staining positively for MDM2/CDK4, and it underscores how immunohistochemistry can potentially serve as a pitfall when differentiating this rare entity from retroperitoneal sarcomas.

Nonlymphoid Hematopoietic Diseases Presenting in Bone, Soft Tissue, and Other Extranodal Sites

Context.—

Although rare in everyday practice, the initial presentation of hematopoietic neoplasms other than lymphoma in the musculoskeletal system and other extranodal sites can generate challenging diagnostic problems for surgical pathologists.

Objective.—

To review the morphologic and immunophenotypic features of various nonlymphoid hematopoietic diseases presenting at extranodal sites, with emphasis on the inherent diagnostic pitfalls and differential diagnoses of these entities to aid surgical pathologists in their accurate recognition.

Data Sources.—

Cases reviewed herein represent both in-house and consult cases seen at our institution between 2010 and 2021.

Conclusions.—

Entities that present in this way include myeloid neoplasms and histiocytic/dendritic cell neoplasms. These tumors commonly cause nonspecific symptoms, and their histologic appearance can overlap with a variety of benign neoplasms and reactive processes. This can lead to delay in diagnosis and intervention with potentially lifesaving therapy; thus, accurate and expedient recognition is of paramount importance.

Concomitant malignancies in the neck: follicular dendritic cell sarcoma; a rare tumour presenting as a right-sided neck nodal mass and papillary carcinoma thyroid

Follicular dendritic cell sarcoma is a rare low-grade sarcoma of mesenchymal origin. It involves the lymph nodes more commonly and rarely extranodal sites. The most common lymph node is cervical and usually presents as a painless asymptomatic mass. More often, it is a misdiagnosis, and there is a delay in treatment. It is rarely associated with Castleman disease, myasthenia gravis. Diagnosis of this condition is by histopathology and immunochemistry. Surgery is the primary modality of treatment, and adjuvant therapy has been tried with no definite trials due to the rarity of the disease. Here, we report a case of concomitant follicular dendritic sarcoma of the right cervical lymph node and papillary carcinoma of the thyroid managed in our institute. There was a line of investigations approaching towards a diagnosis, and she underwent total thyroidectomy and right modified radical neck dissection.

18F-FDG PET/CT in Uterine Follicular Dendritic Cell Sarcoma

ABSTRACT

A 46-year-old woman presented with menorrhagia, abdominal distension, and neck mass for 3 months. Ultrasonography detected a large intra-abdominal mass and enlarged neck lymph nodes. Further 18F-FDG PET/CT scan revealed lesions with intense 18F-FDG avidity in abdominal cavity and neck. The patient underwent a biopsy of the uterine, and the diagnosis of uterine follicular dendritic cell sarcoma was finally achieved. After 6 cycles of CHOP-like chemotherapy, 18F-FDG PET/CT showed complete metabolic and morphologic resolution for follicular dendritic cell sarcoma.

Follicular Dendritic Cell Sarcoma of the Tonsil: A Multimodality Approach

Follicular dendritic cell sarcoma (FDCS) accounts for < 0.4% of soft tissue sarcomas. Only 35 cases of tonsillar FDCS have been reported, and majority had localized presentation. We present a case of FDCS of the tonsil, wherein a well-coordinated trimodality approach provided good disease control in advanced disease. A 53-year-old man presented with a painless and enlarging neck mass of 11-month duration, with no other symptoms. Close examination revealed a 10 × 5 cm mass at the left carotid triangle, and a 3.2 × 2.2 cm mass at the left tonsillar fossa. Imaging revealed the tumor to be unresectable due to its attachment to the great vessels. There were no distant metastases. Biopsy and immunohistochemistry were initially deemed consistent with an undifferentiated sarcoma. Palliative chemotherapy was given using single agent doxorubicin and subsequent dacarbazine, resulting in partial response and stable disease, respectively. Pathological re-evaluation was pursued because of the uncharacteristic slow progression of the tumor, revealing diffuse positivity for CD21 and negative for CD1A and CD34, consistent with FDCS. The patient underwent three cycles of gemcitabine plus docetaxel resulting in 50% regression. This allowed dissection of level IB-V lymph nodes and subsequent radiotherapy for the neck and tonsillar mass, with weekly gemcitabine as a radiosensitizer. Evaluation 8 months post-treatment showed no signs of disease progression. Treatment-related complications included radiation dermatitis and swallowing dysfunction, which both resolved on follow-up. This case highlights the multidisciplinary management of a rare type of sarcoma in an uncommon anatomic location. Precise pathologic diagnosis is important in soft tissue sarcoma because of its therapeutic implications. For FDCS, effective response may still be achieved in the third-line setting.

Follicular dendritic cell sarcoma of the cervical lymph node diagnosed on fine needle aspiration cytology

Follicular dendritic cell sarcomas (FDCS) are rare tumours of lymph nodes and extranodal tissues which are grouped with the histiocytic and dendritic cell neoplasms. The diagnosis is usually made after thorough clinical and pathological examination with immunohistochemical analysis. Difficulties persist in diagnosing FDCS on cytological preparations. We report herein a case of a 57-year-old female who presented with a right neck mass of 5 months duration. Computed Tomography (CT) imaging of the neck reported a necrotic right level IIb lymph node and asymmetric fullness of the right palatine tonsil. Fine needle aspiration (FNA) biopsy revealed numerous spindle, oval and stellate neoplastic cells, arranged singly and in syncytia with moderate nuclear pleomorphism, vesicular chromatin pattern, and prominent nucleoli, sprinkled with small lymphocytes. The tumour cells were strongly diffusely positive for CD21, CD23, and D2-40 immunostaining on cell bock sections, but were negative for CD1a and CD34, supporting the diagnosis of FDCS. Follow-up surgical pathology on the resection showed histopathological features and an immunohistochemical profile consistent with FDCS.

Follicular Dendritic Cell Sarcoma of the Chest

Follicular dendritic cell sarcoma is a rare, low-grade cancer derived from follicular dendritic cells, which serve as accessory cells to the lymphoid system. Here, we describe the case of a 57-year-old man who had a mediastinal mass with aortic involvement incidentally identified during evaluation for indeterminate pulmonary nodules. The mass, later diagnosed as follicular dendritic cell sarcoma, was successfully treated with surgical resection aided by placement of endovascular aortic stent graft.

Primary Follicular Dendritic Cell Sarcoma of Breast: 2 Further Cases with Review of the Literature

Follicular dendritic cell sarcoma (FDCS) is a tumor derived from antigen-presenting cells and can occur within lymphoid tissue or at extranodal sites. FDCS of the breast is remarkably rare, with only 4 cases previously reported in literature. FDCS appears grossly as a well-circumscribed, firm mass with a grey-yellow surface, areas of necrosis, and histologically comprises of spindled, oval, or epithelioid cells with intensely eosinophilic cytoplasm. Immunohistochemistry plays a key role in its diagnosis. Here we describe 2 cases of FDCS of breast in 2 women aged 70 and 35 years old, who presented with a palpable lump in the breast. One patient had concomitant invasive ductal carcinoma as well. We highlight the key histopathological and immunohistochemical features of the tumor.

Follicular dendritic cell sarcoma: Cytomorphologic features and diagnostic challenges

Follicular dendritic cell sarcoma (FDCS) is a rare malignant neoplasm, which primarily arises in lymph nodes with occasional cases occurring in extranodal locations. The diagnosis is often challenging particularly on cytology fine needle aspiration due to overlapping morphologic and immunohistochemical features. We present a case of FDCS diagnosed in an otherwise asymptomatic 33-year old male. The aim of our case report is to highlight the key cytomorphologic features and discuss various differential diagnoses of this unusual entity.

Extranodal Follicular Dendritic Cell Sarcoma-A Review: "What the Mind Does Not Know the Eye Does Not See"

Follicular dendritic cell sarcoma (FDCS) is an intermediate-grade malignancy of follicular dendritic cells, which are derived from mesenchymal stem cells. Nodal FDCS is well-recognized. However, when it occurs at an extranodal site, it may not be recognized and is often misdiagnosed. These tumors exhibit a variable spindle to epithelioid cell morphology with a lymphocytic infiltrate and a distinct immunophenotype. The World Health Organization has classified this entity under tumors of hematopoietic and lymphoid tissue, that is, histiocytic and dendritic cell neoplasms. However, its occurrence at extranodal sites and its behavior and management more closely resemble that of a soft tissue tumor. Increased awareness about the existence of FDCS at extranodal sites may aid in the reduction of diagnostic errors. We wish to draw attention to this entity by reporting our experience of 54 cases of extranodal FDCS encountered over a period of 14 years and present a review of the literature of this underrecognized entity. We also describe the ontogeny and molecular pathogenesis of this uncommon lesion.

Metastatic follicular dendritic cell sarcoma treated with gemcitabine plus docetaxel with an outstanding survival: A case report and review of literature

Follicular dendritic cell sarcoma responded dramatically to chemotherapy with gemcitabine and docetaxel.

Epstein-Barr virus-negative inflammatory pseudotumor-like variant of follicular dendritic cell sarcoma of the liver: A case report and literature review

Follicular dendritic cell sarcoma (FDCS) can be divided into the conventional type, and the inflammatory pseudotumor (IPT)-like variant type. Epstein-Barr virus (EBV) infection is considered to be closely associated with the pathogenesis of IPT-like variant of FDCS. Hepatic FDCS has an exceedingly low incidence of only 29 cases reported, with most of these tumors being classified as the IPT-like type. We report a case of an IPT-like variant of FDCS of the liver in a 61-year old man who presented with no marked symptoms. The patient underwent laparoscopic surgery for the mass and was well during a 13-month follow-up periods. The postoperative pathological examination found a proliferation of spindle cells and a diffuse infiltration of inflammatory cells within the tumor. Immunohistochemistry revealed that neoplastic cells were positive for CD23, clusterin, fascin, and PD-L1, and weakly positive for CD35, SMA, and D2-40. The infiltrating lymphocytes were strongly positive for PD1, and IgG4-positive plasma cells were less than 10 cells/high-power field. In situ hybridization for Epstein-Barr virus encoded RNA (EBER) was negative. To our knowledge, the present case is the second case of hepatic IPT-like variant of FDCS without EBV involvement, indicating that EBV infection is not an absolute prerequisite for a diagnosis of the IPT-like variant of FDCS.

Multidisciplinary diagnosis and treatment of recurrent follicular dendritic cell sarcoma in abdomen: A case report

RATIONALE

Follicular dendritic cell sarcoma (FDCS) is a rare malignant tumor derived from follicular dendritic cells, and is often associated with Castleman disease. Here we present a rare case of paraneoplastic pemphigus (PNP) with FDCS which required multidisciplinary approach for the diagnosis and treatment.

PATIENT CONCERNS

A 28-year-old Chinese female had FDCS recurrence, and primary clinical manifestation was PNP.

DIAGNOSES

PNP with FDCS.

INTERVENTIONS

The patient received gamma globulin infusion, took anlotinib, and underwent plasma exchange therapy.

OUTCOMES

The skin lesions recovered and there was no evidence of tumor recurrence.

LESSONS

The diagnosis and management of PNP with FDCS require close cooperation among surgeons, dermatologists, hematologists, otolaryngologists, oncologists, radiologists, pathologists, and respiratory doctors. The interesting clinical manifestations of this patient provide a multifaceted approach to the investigation of the interactions among FDCS, Castleman disease, and PNP.

Epstein-Barr virus-positive inflammatory follicular dendritic cell sarcoma presenting as a solitary colonic mass: two rare cases and a literature review

AIMS

Follicular dendritic cell (FDC) sarcoma is a rare neoplasm originating from follicular dendritic cells in germinal centres. It is classified as conventional and Epstein-Barr virus (EBV)-positive inflammatory FDC sarcoma according to the 2019 World Health Organization classification of digestive system tumours; the latter is rarer. So in view of the rarity and difficulty in diagnosis, the aim of the manuscript is to share our experience of diagnosing EBV-positive inflammatory FDC sarcoma.

METHODS AND RESULTS

Here, we describe the clinicopathological features, gross description, histomorphology, immunophenotype, EBV-encoded mRNA (EBER) in-situ hybridisation, gene rearrangement and clinical follow-up of two patients with EBV-positive inflammatory FDC sarcoma in the colon, and review the relevant literature. The tumours were found in two males, aged 53 and 48 years, respectively, with a tumour diameter between 10 and 45 mm. Both cases occurred in the colon and presented as pedunculated colonic masses. Microscopically, scanty atypical ovoid to spindle neoplastic cells were mixed in a background of florid lymphoplasmacytic infiltration. The nuclei of these atypical cells showed vesicular chromatin and small, distinct nucleoli. Immunohistochemistry demonstrated that the atypical stromal cells were positive for CD21, CD23, CD35, and D2-40. EBER in-situ hybridisation also gave positive results in two cases. There was a mean follow-up of 9 months (range, 7-11 months).

CONCLUSION

EBV-positive inflammatory FDC sarcoma is an extremely rare tumour with a distinct morphology and phenotype. Therefore, it is very important to recognise it particularly for correct diagnosis and prevention of misdiagnosis and mistreatment.

Follicular dendritic cell sarcoma in the right chest wall: A case report

RATIONALE

Follicular dendritic cell sarcoma (FDCS) is a rare malignant tumor that originates from germinal center follicular dendritic cells, and can occur at both nodal and extranodal sites. There are very few described cases of FDCS arising in the chest wall.

PATIENT CONCERNS

A 44-year-old male patient presented with a history of right chest wall pain for 5 months.

DIAGNOSES

Positron emission tomography/computed tomography showed a significant increase in F-fluorodeoxyglucose uptake and multiple small axillary lymph nodes without hypermetabolic lesions. Immunohistochemistry results of a core-needle biopsy indicated FDCS, which was consistent with the postoperative pathological examination.

INTERVENTIONS

The patient underwent tumor resection with lymphadenectomy of level I axillary nodes. No metastasis in the lymph nodes was observed in the postoperative pathological examination. The patient did not accept chemotherapy or radiotherapy.

OUTCOMES

After 18 months, the patient remains in good condition with no evidence of disease recurrence.

LESSONS

This report highlights a rare case of a FDCS arising in the chest wall. Accurate clinical diagnosis and staging of this rare malignant sarcoma is essential for the developmnt of effective treatment strategies. Preoperative F-fluorodeoxyglucose positron emission tomography/computed tomography scanning combined with core-needle biopsy could provide differentiation between benign and malignant tumors, as well as lymph node involvement and metastatic status.

Intra-abdominal Follicular Dendritic Cell Sarcoma (FDCS): Series of 18 cases of a rare entity from Pakistan

OBJECTIVES

Follicular Dendritic Cell Sarcoma (FDCS) is a rare neoplastic proliferation of dendritic cells which are immune accessory cells found in both lymphoid and non-lymphoid organs. FDCS can thus occur in lymph nodes as well as non-lymphoid organs. Intraabdominal FDCS is even rarer. Our aim was to describe the clinical and morphological features of intra-abdominal FDCSs diagnosed in our practice and to review published literature on FDCSs including intra-abdominal FDCSs.

METHODS

All cases of FDCSs diagnosed between January 1, 2008 and December 31, 2019 were included in the study. Slides of the cases were reviewed and clinical follow up was obtained.

RESULTS

A total of 18 cases of intraabdominal FDCS were diagnosed during the study period. Age range was 17 to 55 years. Mean and median ages were 28 and 29 years respectively. Of the 18 patients, 11 were male and 7 were females. Colon was involved in 9 cases and appendix in 2 cases. 9 cases were received as resection specimens while 9 cases were received as slides and blocks for second opinion. Tumor size ranged from 2.7 to 26 cm. Average tumor size in these 9 cases was 8.2 cm and in 6 of these 9 cases, tumor size was greater than 6 cm in largest dimension. Grossly, tumors were nodular or polypoid and had a fleshy, grey white, homogeneous cut surface. Histologically, all 18 cases showed proliferation of plump to spindle shaped cells arranged in a fascicular or storiform pattern. Tumor cells had mild to moderately pleomorphic spindle to ovoid vesicular nuclei with fine chromatin and inconspicuous to variably conspicuous nucleoli, and moderate amount of pale eosinophilic cytoplasm. Mitotic activity was usually brisk. CD21 and CD23 were positive in all 18 cases. Resection margins were negative in all 9 resection specimens. Lymph nodes positive for metastases were seen in 4 cases. Follow up was available in 13 cases. Recurrence was seen in 6 patients, out of which 3 patients died of disease 15, 17- and 24-months following resection. 1 patient with appendiceal FDCS was free of disease almost 12 years after surgery but recently developed recurrence and is currently undergoing chemotherapy. 6 patients were alive and well at the time of follow-up 5 to 68 months after resection. None of them had developed recurrence or metastases at the time of follow up. 8 of the 13 patients received chemotherapy and/or radiotherapy post-surgical resection.

CONCLUSION

Colon was involved in 9 of our 18 cases. Lymph nodes were positive for metastases in 4 out of 9 resection specimens. All cases were diagnosed based on morphology supported by positivity for immunohistochemical stains CD21 and CD23. Histological factors associated with aggressive behavior were seen in 14 cases. Majority of patients had an aggressive clinical course.

Myeloid, mast cell, histiocytic and dendritic cell neoplasms and proliferations involving the spleen

Splenic involvement and consequent splenomegaly are usually seen as part of systemic involvement by myeloid neoplasms as well as mast cell and histiocytic neoplasms. Primary splenic involvement by these neoplasms is rare. Splenectomy is usually not performed for establishing a diagnosis of these entities. However, in rare instances, the pathologist may need to evaluate the spleen secondary to splenic rupture or palliative splenectomy to alleviate symptoms related to splenomegaly. This review article describes the clinicopathologic features of a broad group of myeloid, mastocytic, and histiocytic proliferative and neoplastic disorders.

Follicular dendritic cell sarcoma of the parotid gland: A case report

Follicular dendritic cell sarcoma (FDCS) is an exceedingly rare malignant neoplasm. The management of this tumor is fully challenging due to its rarity and lack of documentations. We share a case with primary parotid FDCS. This case report depicts the clinicopathological features of FDCS, which intends to serve as a reference to clinicians in its correct identification.

Pancreatic Inflammatory Pseudotumor-Like Follicular Dendritic Cell Tumor

Follicular dendritic cell sarcoma (FDCS) is a rare and underdiagnosed malignant neoplasm which characteristically presents as a solitary, slow-growing mass with no discrete symptoms. Histologically, lymphocytes and spindle cells featuring large nucleoli in a whorled pattern are usually seen. FDCS is classically found in cervical and axillary lymph nodes, with occasional involvement of extranodal sites. Inflammatory pseudotumor-like follicular dendritic cell tumor (IPT-like FDCT) is an uncommon subcategory of this neoplasm, demonstratively linked to the Epstein-Barr virus (EBV). This neoplasm can present similarly to FDCS, but systemic symptoms may be seen. Although, often found in the spleen and occasionally the liver, IPT-like FDCT has not previously been described within the pancreas. Presented, is an IPT-like FDCT of the pancreas and spleen of a 70 years old woman. Histologic features include variably sized geographic suppurative granulomas with chronic inflammatory cells and an atypical spindle cell proliferation with prominent nucleoli. Positivity for CD45 and CD68 in the larger spindled cells points to an inflammatory pseudotumor subtype and co-expression of CD21, CD23, and CD35 were indicative of follicular dendritic differentiation. The pseudotumor additionally demonstrated EBV-encoded RNA (EBER) positivity typical of IPT-like FDCT. Differentiation between inflammatory pseudotumor (IPT) and inflammatory myofibroblastic tumor (IMT) is additionally discussed.

Temozolomide targets and arrests a doxorubicin-resistant follicular dendritic-cell sarcoma patient-derived orthotopic xenograft mouse model

Follicular dendritic cell sarcoma (FDCS) is a very rare and highly recalcitrant disease. A patient's doxorubicin-resistant FDCS was previously established orthotopically on the right high thigh into the biceps femoris of mice to establish a patient-derived orthotopic xenograft (PDOX) model. The aim of the present manuscript was to identify an effective drug for this recalcitrant tumor. Here, we evaluated the efficacy of temozolomide (TMZ), trabectedin (TRAB) and pazopanib (PAZ) on the FDCS PDOX model. PDOX mouse models were randomized into five groups of eight to nine mice, respectively. Group 1, untreated control with PBS, i.p.; Group 2, treated with doxorubicin (DOX), 2.4 mg/kg, i.p., weekly for 3 weeks; Group 3, treated with PAZ, 50 mg/kg, oral gavage, daily for 3 weeks; Group 4, treated with TMZ, 25 mg/kg, oral gavage, daily for 3 weeks; Group 5, treated with TRAB, 0.15 mg/kg, i.v., weekly for 3 weeks. Body weight and tumor volume were assessed 2 times per week. TMZ arrested the FDCS PDOX model compared to the control group (p < 0.05). PAZ and TRAB did not have significant efficacy compared to the control group (p = 0.99, p = 0.69 respectively). The PDOX tumor was resistant to DOX (p= 0.99). as was the patient. The present study demonstrates that TMZ is effective for a PDOX model of FDCS established from a patient who failed DOX treatment, further demonstrating the power of PDOX to identify effective therapy including for tumors that failed first line therapy.

Primary hepatic follicular dendritic cell sarcoma: A case report

BACKGROUND

Follicular dendritic cell sarcoma (FDCS) is an uncommon type of tumor with low incidence. To date, no standard treatment for the disease has been established. Surgery remains the main treatment. Adjuvant chemotherapy and radiotherapy are optional approaches. Metastatic cases require multidisciplinary collaborative treatments. However, the choice of chemotherapeutic drugs is controversial.

CASE SUMMARY

A 66-year-old Chinese woman presented to our hospital complaining of intermittent pain of right upper quadrant. An enhanced computed tomography (CT) scan of the abdomen revealed hepatocellular carcinoma. Subsequently, the patient underwent a radical partial hepatectomy. Primary FDCS of the liver was diagnosed pathologically. Except for regular follow-up examinations, the patient did not receive adjuvant chemotherapy or radiotherapy. However, fluorine-18-fluorodeoxyglucose positron emission tomography/CT (PET/CT) confirmed lymph node metastases in the space of ligamentum hepatogastricum and pancreatic head, as well as the portacaval space. The patient was given systemic chemotherapy with gemcitabine and docetaxel for she was unsuitable for surgery. Satisfactorily, the metastatic lymph nodes were significantly reduced to clinical complete remission after eight cycles of chemotherapy. Then, strengthened radiotherapy was followed when the patient rejected the opportunity of surgery. Eventually, the carcinoma got better control and the patient was free of progression.

CONCLUSION

This case highlights the importance of making suitable chemotherapy regimens for the rare tumor. The combination of gemcitabine, docetaxel, and consolidated radiotherapy may offer a new promising option for the treatment of metastatic hepatic FDCS in the future.

Anaplastic Kaposi's Sarcoma of the Adrenal in an HIV-negative Patient With Literature Review

Kaposi's sarcoma (KS) is a peculiar tumor of viral etiology, with the HHV8 rhadinovirus playing a fundamental role in its development. Several epidemiological categories of KS have been identified, of which the sporadic, endemic, iatrogenic, and the epidemic are the main ones. Several histologic disease morphologies have been described, such as inflammatory, angiomatous, spindle cell, mixed, and the anaplastic (sarcomatous) subtypes. The skin of the limbs is most commonly affected, but any other organ or site may be involved. Microscopically KS may enter the differential diagnosis with several different entities, and for this purpose the immunohistochemical detection of the viral latent nuclear antigen-1 (LNA-1) may be crucial. Sporadic KS is usually benign, but rarely it may be aggressive. Anaplastic histology heralds an ominous course in any clinical context. We report a case of anaplastic retroperitoneal KS, occurring in an HIV-negative adult man. This patient presented with a huge left suprarenal mass, which was totally resected, and initially diagnosed as inflammatory leiomyosarcoma, because of the monomorphic spindle cell tumor morphology. After 12 years the tumor recurred locally as an unresectable mass, which was biopsied and examined. At the time of recurrence, the histologic slides of the primary tumor were reviewed, and the previous diagnosis was changed to that of atypical KS. Histologically the recurrent tumor showed both spindle cell and epithelioid appearances. Strongly diffuse HHV8/LAN-1 immunopositivity was documented in both tumors. The final diagnosis for the entire case was anaplastic KS. Then, the patient died in a few months.

Paraneoplastic disorders associated with miscellaneous neoplasms with focus on selected soft tissue and Undifferentiated/ rhabdoid malignancies

A variety of soft tissue and visceral neoplasms have been associated with constitutional symptoms and signs including fever, fatigue, arthritis and laboratory abnormalities such as elevated erythrocyte sedimentation rate, leukocytosis with marked neutrophilia, anemia, thrombocytosis and others. This review addresses three main neoplastic categories that are associated with specific paraneoplastic phenomena: (1) neoplasms having in common the presence of diffuse mixed inflammatory infiltration (closely simulating an inflammatory pseudotumor) and frequently associated with constitutional symptoms; (2) neoplasms with undifferentiated, anaplastic or rhabdoid cell morphology (frequently SWI/SNF-deficient) associated with diverse paraneoplastic manifestations; and (3) paraneoplasia associated with neoplasms carrying specific gene fusions such as solitary fibrous tumor (STAT6-NAB2 gene fusions), infantile fibrosarcoma and congenital mesoblastic nephroma (ETV6-NTRK3 gene fusions), and angiomatoid fibrous histiocytoma (EWSR1-CREB1 & EWSR1-ATF1 fusions).

Primary Tonsillar Epithelioid Follicular Dendritic Cell Sarcoma: Report of a Rare Case Mimicking Undifferentiated Carcinoma and a Brief Review of the Literature

We present a 52 years old male with a left tonsillar follicular dendritic cell sarcoma with prominent epithelioid features that on light microscopical examination bore a striking resemblance to a lymphoepithelial or undifferentiated carcinoma. The tumor was immunohistochemically positive for CD21 and CD35 and negative for cytokeratins. Two distinct histopathological features (both present in our case) that may serve as clues to the correct diagnosis on light microscopical examination were formation of ectatic pseudovascular spaces lined by malignant cells and the presence of non-neoplastic multinucleated giant cells. Familiarity with the above-mentioned morphological clues, and awareness that this tumour may occur in anatomical sites outside the lymph node, are essential for accurate diagnosis.

Profiles of genomic alterations in primary esophageal follicular dendritic cell sarcoma: A case report

RATIONALE

Follicular dendritic cell (FDC) sarcoma is a rare tumor with FDC differentiation that typically arises within lymph nodes but can also occur extranodally. To date, the primary esophageal FDC sarcoma has not been reported in the English literature.

PATIENT CONCERNS

We described a 67-year-old female who foremostly presented with dysphagia, and the patient was readmitted due to a dry cough and pain of his right shoulder 2 years after initial treatment.

DIAGNOSES

Primary esophageal FDC sarcoma with the right superior mediastinal lymph node metastasis.

INTERVENTIONS

The esophageal tumor was removed by endoscopic submucosal dissection at the first hospitalization. At the second hospitalization 2 years after the initial visit, the tracheal stent loaded with (125) iodine radioactive seeds was placed. The profiles of genetic variations and immunotherapeutic biomarkers were also explored by next-generation sequencing protocol from the patient's blood, esophageal primary, and mediastinal metastatic tumor samples.

OUTCOMES

The patient's symptom transitorily relieved, but she gave up further treatment and died 2 months after the tracheal stent was placed. As for the genomic alterations, we found 9 gene mutations in all the samples, including checkpoint kinase 2(CHEK2), FAT atypical cadherin 1 (FAT1), tumor protein 53 (TP53), DPYD, ERBB2 interacting protein (ERBB2IP), FBXW7, KMT2D, PPP2R1A, TSC2, whereas amplification of MYC was only in the metastatic example. The analysis of clonal evolution and phylogenetic tree showed the propagation and replay of polyclonal esophageal FDC sarcoma. At the same time, the detection of biomarkers for immunotherapy revealed microsatellite stable and mismatch repair-proficient (pMMR), which predicted a relatively poor anti-programmed death (PD-1)/programmed death ligand (PD-L1) immunotherapy outcome. On the contrary, the tumor mutational burdens were 10 mutations per 1 million bases in both the primary and metastatic tumor sample, which ranked the top 23.3% in solid tumors mutational burdens database of Geneseeq and might be a good predictor of the efficacy of anti-PD-1/PD-L1 immunotherapy.

LESSONS

To the best of our knowledge, this case report announced the first case of extranodal primary esophageal FDC sarcoma in the world, and firstly revealed its unique genetic alterations profiles, which might contribute to further in-depth study of this rare disease.