Cytological diagnosis of follicular dendritic cell sarcoma: A case report and review of literature

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

BACKGROUND

Follicular dendritic cell sarcoma is a malignant neoplasm derived from germinal center follicular dendritic cells, which both share a characteristic immunophenotype (namely CD21, CD23, and CD35). Cytomorphologic descriptions are few, consisting of only 26 prior cases from 24 publications. Identification by cytologic means appears challenging as the majority of previous reports disclose an erroneous or indeterminate initial cytologic diagnosis. Herein, we present the largest cytology series to date with the aim of expanding upon this small body of literature and discuss possible factors resulting in misinterpretation.

MATERIALS AND METHODS

A retrospective search was conducted from 2 academic medical centers to identify histologically confirmed cases of follicular dendritic cells with an associated cytologic component. Clinicopathologic data were tabulated and a comparative analysis of cytomorphologic and immunohistochemical features was performed.

RESULTS

Seven separate cases were identified. All cases showed cohesive tumor cells with a characteristic voluminous, ill-defined cytoplasm with interconnecting fibrillary processes and intimately admixed mature lymphocytes. Features were maintained across various cytologic preparations, including conventional smear, liquid-based cytology, and touch imprint. Unusual immunohistochemical profiles were noted in a subset of cases.

CONCLUSIONS

Cytomorphology is highly conserved across cases and preparations; however, a propensity for aberrant immunoexpression may contribute to diagnostic errors. Cytomorphologic features, supported by immunohistochemistry, suggest fine-needle aspiration as a reasonable diagnostic modality. Tumors with these features should include CD21, CD23, and/or CD35 in the workup.

Follicular dendritic cells

Follicular dendritic cells (FDCs) are unique accessory immune cells that contribute to the regulation of humoral immunity. They are multitasker cells essential for the organization and maintenance of the lymphoid architecture, induction of germinal center reaction, production of B memory cells, and protection from autoimmune disorders. They perform their activities through both antigen-driven and chemical signaling to B cells. FDCs play a crucial role in the physiological regulation of the immune response. Dis-regulation of this immune response results when FDCs retain antigens for years. This provides a constant antigenic stimulation for B cells resulting in the development of immune disorders. Antigen trapped on FDCs is resistant to therapeutic intervention causing chronicity and recurrences. Beyond their physiological immunoregulatory functions, FDCs are involved in the pathogenesis of several immune-related disorders including HIV/AIDS, prion diseases, chronic inflammatory, and autoimmune disorders. FDCs have also been recently implicated in rare neoplasms of lymphoid and hematopoietic tissues. Understanding FDC biology is essential for better control of humoral immunity and opens the gate for therapeutic management of FDC-mediated immune disorders. Thus, the biology of FDCs has become a hot research area in the last couple of decades. In this review, we aim to provide a comprehensive overview of FDCs and their role in physiological and pathological conditions.

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: 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.

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.

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.

A Proposal for the Performance, Classification, and Reporting of Lymph Node Fine-Needle Aspiration Cytopathology: The Sydney System

BACKGROUND

The evaluation of lymph nodes (LN) by fine-needle aspiration cytology (FNAC) is routinely used in many institutions but it is not uniformly accepted mainly because of the lack of guidelines and a cytopathological diagnostic classification. A committee of cytopathologists has developed a system of performance, classification, and reporting for LN-FNAC.

METHODS

The committee members prepared a document that has circulated among them five times; the final text has been approved by all the participants. It is based on a review of the international literature and on the expertise of the members. The system integrates clinical and imaging data with cytopathological features and ancillary techniques. The project has received the endorsement and patronage of the International Academy of Cytology and the European Federation of the Cytology Societies.

RESULTS

Clinical, imaging, and serological data of lymphadenopathies, indications for LN-FNAC, technical procedures, and ancillary techniques are evaluated with specific recommendations. The reporting system includes two diagnostic levels. The first should provide basic diagnostic information and includes five categories: inadequate/insufficient, benign, atypical lymphoid cells of undetermined/uncertain significance, suspicious, and malignant. For each category, specific recommendations are provided. The second diagnostic level, when achievable, should produce the identification of specific benign or malignant entities and additional information by utilizing ancillary testing.

CONCLUSION

The authors believe that the introduction of this system for performing and reporting LN-FNAC may improve the quality of the procedure, the report, and the communication between cytopathologists and the clinicians. This system may lead to a greater acceptance and utilization of LN-FNAC and to a better interdisciplinary understanding of the results of this procedure.

Role of Adjuvant Chemotherapy in Extranodal Follicular Dendritic Cell Sarcoma

Extranodal follicular dendritic cell sarcomas (FDCSs) are an uncommon entity, commonly misdiagnosed because of the morphologic similarities with other neoplasias. Previously, FDCSs were not considered a differential diagnosis because of the limited use of immunohistochemistry. Surgical excision is the treatment of choice for localized FDCS. The role of chemotherapy has not been determined for this rare disease. We report 2 cases of metastatic extranodal intra-abdominal FDCS, initially misdiagnosed as gastrointestinal stromal tumor, their clinicopathological features, literature review, and the role of adjuvant chemotherapy.