Follicular Dendritic Cell Sarcoma

Abstract

Follicular dendritic cell sarcoma is an uncommon neoplastic proliferation of spindled to ovoid cells with morphologic and immunophenotypic features similar to normal follicular dendritic cells. While most follicular dendritic cell sarcomas arise from lymph nodes, at least one-third occur in extranodal sites. A broad differential diagnosis can be developed--as this tumor has morphologic features similar to other tumors, hence creating a diagnostic pitfall--but its immunophenotypic profile is quite specific and is diagnostically crucial. Herein, we review the pathogenesis; histologic morphology; and immunohistochemical, electron microscopy, and clinical features, including treatment and prognosis, of follicular dendritic cell sarcomas. We will briefly describe the role of molecular studies including utility of BRAF mutations in diagnosing this tumor.

Follicular dendritic cell sarcoma of the porta hepatis

“…Most cases of FDC sarcoma are of unknown aetiology, however associations exist with Castleman’s disease, myasthenia gravis and paraneoplastic pemphigus 2. FDC sarcoma is a rare primary sarcoma of the liver which, in total, constitutes less than 0.1% of primary liver tumours 4.…”

“…Presenting symptoms of an intra-abdominal FDC sarcoma are non-specific and may include abdominal pain, malaise and weight loss 5. A subtype of FDC sarcoma called the inflammatory pseudotumour (IPT)-like subtype occurs almost exclusively in the liver and spleen6 and has unique histological findings including cellular growth into fascicles and sheets, vesicular nuclei, a background containing lymphocytes and plasma cells, and Reed-Sternberg-like nuclear atypia 2. The IPT-like FDC sarcoma is strongly associated with Epstein-Barr virus (EBV) positivity, female gender preference2 4 and significant inflammatory cell infiltration 4.…”

“…The differential diagnosis for FDC sarcoma is wide, including, but not limited to, meningioma, thymoma, gastrointestinal stromal tumour and melanoma 8. Therefore, immunohistochemical markers such as CD21, CD23 and/or CD35 are crucial for narrowing the differential and arriving at a diagnosis 2. Additionally, stains such as clusterin and podoplanin are highly specific for FDC sarcoma 2.…”

“…Follicular dendritic cells (FDCs) reside within germinal centres and function to present immune complexes to B-cells, produce cytokines and chemokines, and produce factors that attract B-cells 1. FDC sarcoma is an extremely rare neoplasm of FDCs,1 with two-thirds of cases affecting the lymph nodes and one-third of cases involving extranodal sites such as the gastrointestinal tract, soft tissue, tonsils or skin 2. Of the extranodal manifestations of FDC sarcoma, abdominopelvic involvement is the most common, followed by neck and thoracic involvement, and the rarest of this group involves the breast and skin 3.…”

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

“…Neoplastic proliferation of spindled to ovoid cells with morphologic and immunophenotypic features are shown, similar to those of normal FDC [4,5]. FDC serve as an antigen presenting cells to B-lymphocytes [6].…”