Inflammatory pseudotumor-like follicular dendritic cell tumor of the liver with expression of estrogen receptor suggests a pathogenic mechanism: A case report and review of the literature

The term inflammatory pseudotumor-like follicular dendritic cell tumor has been suggested for a follicular dendritic cell tumor of the liver associated with a dense inflammatory infiltrate and Epstein-Barr virus infection. This tumor is less aggressive than usual intraabdominal follicular dendritic cell sarcoma and shows a strong female predominance; however, the pathogenesis is uncertain. We report the case of a 59-year-old woman who presented with a 6-cm mass in the liver. Histological examination showed spindle cells with a storiform pattern and prominent inflammatory infiltrate mimicking inflammatory pseudotumor. Spindle cells expressed follicular dendritic cell markers CD21 and CD35, and were positive for Epstein-Barr virus-encoded RNA and LMP-1 protein. In addition, neoplastic cells expressed estrogen receptor (ER). Fifteen cases of inflammatory pseudotumor-like follicular dendritic cell tumor of the liver including the case we describe here have been reported in the literature. A review of the literature disclosed that normal follicular dendritic cells may express ER; however, extensive testing has not been previously reported in follicular dendritic cell sarcoma. The female predominance and the expression of ER in the case we report are suggestive of a hormonal role in the pathogenesis and therapy of inflammatory pseudotumor-like follicular dendritic cell tumor of the liver.