Interwoven dendritic processes of follicular dendritic cell sarcoma demonstrated on ultrafast papanicolaou-stained smears: a case report

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.

Cytomorphological Findings of Follicular Dendritic Cell Sarcoma on Fine-Needle Aspiration Cytology

BACKGROUND

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm arising from follicular dendritic cells of germinal centers. The most common site of origin is lymph nodes and it may mimic a variety of tumors at that location, including carcinomas and sarcomas. Diagnosis is frequently missed on cytology as there are very few case reports describing the cytological characteristics of the lesion. Even on histology, a high degree of suspicion is required for an appropriate diagnosis.

CASE

A 60-year-old male presented with a gradually increasing left submandibular mass that had been present for 3 months. Fine-needle aspiration cytology (FNAC) was performed, showing many clusters as well as scattered epithelioid cells with spindled to oval nuclei, nuclear pleomorphism, grooves, inclusions, and uniformly dispersed mature lymphocytes throughout the smears. The diagnosis of FDCS was suspected and was confirmed on histopathology and immunohistochemistry.

CONCLUSION

FNAC can be a cheap, easy, and helpful tool in obtaining a diagnosis of FDCS as there are few characteristic cytological features that are better recognized than histology.

Cytological features of inflammatory pseudotumor-like follicular dendritic cell sarcoma of spleen: A case report

Here, we present the first cytological report of a primary splenic inflammatory pseudotumor-like follicular dendritic cell sarcoma. The 57 year-old male was incidentally found with a 2.2 cm well-demarcated splenic nodule. A sonography guided fine needle aspiration of the lesion was performed. The cytologic smears revealed loosely cohesive fragments of oval to spindle cells in a background of prominent lymphoplasmacytic infiltration. The cells showed sparse chromatin, distinct nucleoli, syncytial cell borders, and occasional cytoplasmic processes. On the liquid-based preparation, several histiocyte-like cells with emperipolesis phenomenon were noted. Scant large atypical cells with prominent, cherry-red nucleoli were found on the cell block sections. The initial cytologic interpretation was "atypical cells cannot exclude classical Hodgkin lymphoma." The subsequent partial splenectomy showed an inflammatory pseudotumor-like follicular dendritic cell sarcoma. The tumor cells were positive for CD21, CD35, smooth muscle actin, and EBER in situ hybridization. The cytologic differential diagnoses are briefly discussed. The knowledge of this rare entity, awareness of its cytomorphology, and proper ancillary tests would be helpful for correct cytologic diagnosis. Diagn. Cytopathol. 2017;45:230-234. © 2016 Wiley Periodicals, Inc.

Dendritic cell sarcoma: a pooled analysis including 462 cases with presentation of our case series

Dendritic cell tumors are extremely rare and current knowledge on these tumors is limited. The characteristics of three dendritic cell sarcoma subtypes and their optimal treatment approaches are not fully clarified. We aimed to make a systematic review of the literature and enrich the current data with five new cases. Pooled analysis of 462 reported cases revealed that the tumor had no age, gender or racial predilection. Our analysis suggests that the young age, advanced stage, intraabdominal involvement and unfavorable histological features (i.e. large tumor size, absence of lymphoplasmacytic infiltration, coagulative necrosis, high mitotic count) may predict poor prognosis. Subtypes of this tumor have different clinical behaviors with interdigitating dendritic cell sarcoma being the most aggressive form. In general, surgery is the most effective treatment modality and adjuvant radiotherapy has no significant effect on overall survival of patients. The role of chemotherapy for the management of advanced disease is controversial.

Dendritic cell tumor in a salivary gland lymph node: a rare differential diagnosis of salivary gland neoplasms

Dendritic cell tumors are extremely rare neoplasms arising from antigen-presenting cells of the immune system. We report a case of a 69-year-old man with an unremarkable medical history who presented with a 2-months history of a gradually enlarging painless, firm, mobile, 2 × 2-cm swelling at the caudal pole of the left parotid gland without systemic symptoms. Histologically, the tumor consisted of a spindle cell proliferation in an intraparotideal lymph node. Based on the histopathologic, immunohistochemical and electron microscopic findings, a dendritic cell tumor, not otherwise specified (NOS) in an intraparotideal lymph node was diagnosed.

The patient underwent complete tumor resection, and is currently free of disease, 2 years after surgery. These extremely rare tumors must be distinguished from other more common tumors in the salivary glands. Awareness that dendritic cell tumors may occur in this localization, careful histologic evaluation and ancillary immunohistochemical and electron microscopical analyses should allow for recognition of this entity.

Histiocytic sarcoma with interdigitating dendritic cell differentiation: a case report with fine needle aspiration cytology and review of literature

A hybrid histiocytic sarcoma-interdigitating dendritic cell sarcoma was found in a small perinephric lymph node of an asymptomatic 80-year-old man, who presented a year ago with two small foci of lung metastasis found during routine chest X-ray. Fine needle aspiration cytology demonstrated interconnecting long and thin cell processes radiating from dendrite-like neoplastic cells with oval, enlongated, reniform, and irregular nuclei with vesicular chromatin and distinct nucleoli. Histology showed spindled epitheliod and histiocytic cells with abundant, slightly eosinophilic cytoplasm with indistinct cell borders and forming fascicles in a vague storiform pattern with interspersed T-lymphocytes. Immunohistochemically, the neoplastic cells were strongly positive for histiocytic markers: CD163, CD68, lysozyme, and PU.1, as well as strongly positive for dendritic cell markers: S100 and fascin, but were negative for CD1a (Langerhans cell marker), CD21/CD35 (follicular dendritic cell markers), B-cell, and T cell markers. This case is compared to the four hybrid histiocytic-dendritic sarcomas reported since 1983.

Cytopathology of a primary follicular dendritic cell sarcoma of the liver of the inflammatory pseudotumor-like type

Follicular dendritic cell (FDC) sarcoma is an exceedingly uncommon tumor of lymph nodes and extranodal tissues. The inflammatory pseudotumor (IPT)-like variant of FDC sarcoma of intraabdominal location is considered a separate entity, with different clinical and pathological features than those of the classic FDC tumor. There have been only 12 cytological reports of FDC sarcomas in the literature. Two of them were metastases to the liver and, like our case, had features of IPT. Fine-needle aspiration biopsy (FNAB) and imprint and scrape cytology from the surgically excised tumor here reported revealed spindle tumor cells with moderate pleomorphism, nuclear grooves, prominent nucleoli, and cytoplasmic processes, admixed with inflammatory cells. To the best of our knowledge, this is the first cytology report of a primary hepatic FDC tumor. The cytological findings permit the recognition of this tumor. However, confirmation by inmunohistochemistry (IHQ) is mandatory for a definitive diagnosis.