A Cytological Review of Follicular Dendritic Cell-Derived Tumors with Emphasis on Follicular Dendritic Cell Sarcoma and Unicentric Castleman Disease

Abstract

Follicular dendritic cells (FDCs) are antigen-presenting cells located in the germinal centers of the lymph nodes. Among the few tumors showing FDC differentiation are follicular dendritic cell sarcoma (FDCS) and Castleman disease (CD), more precisely the unicentric hyaline vascular (HV) variant. Both are relatively rare tumors, and the diagnostic cytological experience is limited to descriptions of isolated cases or small series. The purpose of this review is to bring together all the available cytological published information, and our personal experience, in order to obtain a global idea of the cytological features of these peculiar FDC-derived tumors. The different descriptions of FDCS are very similar, reflecting a tumor that shows repetitive and characteristic cytological features. It shows a dimorphic population of mature lymphocytes and large tumoral cells with partial spindle morphology. Most cases of HV variant of CD can be recognized as benign upon cytology, however a precise diagnosis seems more difficult. It is characterized by reactive lymphocytes mixed with vessels and FDCs, either single or forming syncytial aggregates. Both, FDCS and CD are challenging for cytological diagnosis in which a high index of suspicion is necessary for a correct preoperative assessment. Cytology is very useful for follow-up of recurrences and metastases.

Fine needle aspiration cytology of follicular dendritic cell sarcoma of the stomach masquerading as gastrointestinal stromal tumor: A case report of a unique entity with emphasis on cytomorphology

“…16 The cytomorphologic features closely resemble those on histology, with large, epithelioid and oval to spindly neoplastic cells that have indistinct cell borders, nuclear grooves, and pseudoinclusions alongside a second population of lymphocytes and plasma cells. 16 The tumor cells are characteristically positive for CD21, CD35, and CD23, with positivity rates of 85%, 55%, and 31.7% respectively. 3 Therefore, a panel of these stains is recommended to help make the diagnosis.…”

“…16 On the nice review by Jiménez-Heffernan, 26 cases of FDCS diagnosed on cytology were reported on the literature, most of them from lymph nodes. 16 The cytomorphologic features closely resemble those on histology, with large, epithelioid and oval to spindly neoplastic cells that have indistinct cell borders, nuclear grooves, and pseudoinclusions alongside a second population of lymphocytes and plasma cells. 16 The tumor cells are characteristically positive for CD21, CD35, and CD23, with positivity rates of 85%, 55%, and 31.7% respectively.…”

“…On FNA cytology, follicular dendritic cells can be seen in reactive lymph node germinal center fragments. These cells are voluminous with indistinct borders, syncytial formation, and a tendency of their nuclei to mold 16 . On the nice review by Jiménez‐Heffernan, 26 cases of FDCS diagnosed on cytology were reported on the literature, most of them from lymph nodes 16 .…”

“…These cells are voluminous with indistinct borders, syncytial formation, and a tendency of their nuclei to mold 16 . On the nice review by Jiménez‐Heffernan, 26 cases of FDCS diagnosed on cytology were reported on the literature, most of them from lymph nodes 16 . The cytomorphologic features closely resemble those on histology, with large, epithelioid and oval to spindly neoplastic cells that have indistinct cell borders, nuclear grooves, and pseudoinclusions alongside a second population of lymphocytes and plasma cells 16 …”

A case of retroperitoneal unicentric Castleman's disease missed its exact diagnosis instead of lymphoid tuberculosis for over a decade

“…Abdominal UCD is always mistaken for lymphatic tuberculosis, stromal tumor, neuroendocrine tumor, adrenal adenoma and even accessory spleen, [4] leading to wrong management strategies. Nevertheless, UCD is still with a risk of progression to lymphoma or follicular dendritic cell sarcoma [5,6] , though it is convinced to be an inert disease with a good prognosis. Thus, it is of great importance to make an exact diagnosis at the first visit.…”