Follicular dendritic cell (FDC)
tumor is a rare
neoplasm of the accessory immune system showing FDC differentiation. Histologically, a conventional type and an
inflammatory pseudotumor (IPT-like) type are recognized. The etiology of FDC
tumor is unknown. While rare FDC
tumors were associated with hyaline-vascular
Castleman's disease (HVCD), hepatosplenic IPT-like FDC
tumors consistently harbor
EBV infection. FDC
tumors of the gastrointestinal (GI) tract and mesentery/omentum are exceedingly rare, with only 17 cases reported so far. We report an additional case of an IPT-like FDC
tumor of the ileum and mesentery in a 52-year-old schizophrenic man. The
tumor consisted of highly atypical multinucleated giant cells in a background of intense lymphoid infiltrate with prominent
eosinophilia reminiscent of
Hodgkin's lymphoma.
Tumor cells were immunoreactive for
vimentin, CD21, CD35,
fascin, smooth muscle actin and CD68, but were negative for all lineage-specific lymphoreticular, myeloid, mesenchymal and epithelial markers. Immunostaining for HHV-8 and in situ hybridization for EBV-encoded
RNA (EBER) were negative. Some mesenteric lymph nodes showed HVCD-like changes. The differential diagnostic considerations of this unusual and rare
neoplasm, mainly lymphocyte-rich GI stromal
tumor (GIST),
malignant lymphoma and inflammatory
neoplasia of diverse histogenetic types, will be discussed together with a literature review on gastrointestinal FDC
tumors.