Follicular Dendritic Cell Sarcoma of Gastrointestinal Tract: an Uncommon Lesion, Commonly Missed

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.

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.

An incidental discovery of a gastric follicular dendritic cell sarcoma: A rare case report and a literature review

Introduction: Follicular dendritic cell sarcomas (FDCS) are rare tumours, typically seen in lymph nodes. However, in about one third of the reported cases, a FDCS presents as an extranodal mass. Involvement of the gastrointestinal tract is rare, and the stomach is even rarer with only four cases described to date. The aim of this study was to review clinical characteristics, pathologic features, emphasize on differential diagnosis and discuss therapeutic modalities and prognosis of this rare entity.Case presentation: We report on a 36-year-old female patient with no past medical history, an incidentally discovered FDCS located in the stomach with the presence of lymph node metastasis at the time of diagnosis. The diagnosis of a FDCS was made on morphological and immunohistochemical findings where tumor cells expressed CD21 and CD23. The tumor was resected by gastrectomy with extended para-aortic lymphadenectomy, with uneventful postoperative course.Conclusions: Due to its rarity, FDCS is rarely included in the differential diagnosis of gastrointestinal spindle cell tumors. Complete surgical resection is the current gold standard of treatment.

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.

Normal gastrointestinal tract inflammatory cells and review of select benign hematolymphoid proliferations

The luminal gastrointestinal tract can be a site of robust immune response in which reactive lymphoproliferative processes can sometimes be difficult to distinguish from lymphoma. In this article, we review gastrointestinal tract normal resident inflammatory cells and common nonneoplastic lymphoproliferative responses with emphasis on their differential and links to lymphoma. Topics that are covered include lymphocytic esophagitis, gastric chronic inflammation, mucosa-associated lymphoid tissue, and ulceration, small intestinal lymphoid hyperplasia, celiac disease, microscopic colitis, inflammatory bowel disease, primary immunodeficiency, graft-versus-host disease, and anti-programmed cell death protein-1 effect. We additionally present the less common differential of histiocytic processes within the gastrointestinal tract. The aim of this paper is to serve as a reference for practicing pathologists facing lymphoid, lymphoplasmacytic, or histiocytic processes in the luminal gastrointestinal tract. We hope to help the practicing pathologist distinguish benign from malignant entities and identify features requiring further workup.

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.

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.

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.