Follicular Dendritic Cell Sarcoma
Cyril Fisher, MD, DSc, FRCPath
Key Facts
Terminology
Malignant tumor of follicular dendritic cells
Clinical Issues
Over 1/3 arise in extranodal sites
Can metastasize to lymph nodes and lung
43% recur locally
Microscopic Pathology
Ovoid cells in sheets, fascicles, or storiform whorls
Nuclei distinctive
Dispersed, speckled chromatin, small nucleolus
Prominent nuclear membrane
Long cell processes
Lymphocytes adherent to cell bodies and processes
Rarely dense mixed chronic inflammatory infiltrate
Scattered neoplastic cells
Ancillary Tests
Immunoreactive for
CD21 and CD35 (best used as cocktail)
CD23, podoplanin, fascin, clusterin, EGFR
S100 protein in 40%
EMA in 80%, desmoplakin in 60%
EM shows interdigitating processes with desmosomes
Top Differential Diagnoses
Lymphoepithelial carcinoma
Cytokeratin(+)
Interdigitating reticulum cell sarcoma
Lacks follicular dendritic cell markers
Anaplastic large cell lymphoma
CD30(+), CD45(+)
Spindle cell sarcomas: Relevant markers positive
 Hematoxylin & eosin shows sheets of ovoid tumor cells with admixed adherent lymphocytes and prominent blood vessels. |
 Hematoxylin & eosin shows neoplastic cells that have distinctive oval nuclei with speckled chromatin, small nucleoli, and prominent nuclear membrane  . Indistinct cell margins give syncytial look. |
TERMINOLOGY
Abbreviations
Follicular dendritic cell sarcoma (FDCS)
Synonyms
Dendritic reticulum cell sarcoma
Definitions
Malignant tumor of follicular dendritic cells
Antigen-trapping cells of accessory immune system
Normally in germinal center of lymph node
ETIOLOGY/PATHOGENESIS
Varied Etiologies
Most cases arise de novo
10-15% arise in hyaline-vascular-type Castleman disease
Antecedent dendritic cell hyperplasia and dysplasia
Inflammatory pseudotumor-like variant is associated with EBV
CLINICAL ISSUES
Epidemiology
Age
Young and middle-aged adults
Gender
Slight female predominance
Site
Majority involve lymph nodes
Neck, mediastinum
Spleen, tonsil
Liver
Inflammatory pseudotumor-like variant
Females, in liver or spleen
Over 1/3 arise in extranodal sites
GI tract: Stomach, colon
Mesentery, mesocolon, mediastinum
Head and neck: Pharynx, palate
Soft tissue sites: Neck, axilla, breast
Presentation
Painless mass
Natural History
