[Clinicopathological study on the follicular dendritic cell sarcoma]

To investigate the clinicopathologic features and differential diagnostic methods for follicular dendritic cell sarcoma.

Histological and immunohistochemical examinations and EBER in situ hybridization were used to investigate the pathological features of 5 cases of follicular dendritic cell sarcoma, and related literature was reviewed.

There were 3 males and 2 females with a median age of 54 years (range, 28 - 75 years). The location of lesions included lymph node (2 cases), tonsil (1 case), stomach (1 case), and liver (1 case). The growth patterns were fascicular or whorls and/or diffuse. The neoplastic cells were spindle or ovoid in shape with indistinct border and slightly eosinophilic cytoplasm. The nuclei were round, oval or spindle in shape with small distinct nucleoli. Warthin-Finkeldey-like multinucleated giant cells were detected in two cases. Mitotic figures were found in 1-22/10 HPF. Immunohistochemical staining showed that CD21 and CD23 (3 of 5), CD35 (4 of 5), D2-40 (4 of 4), and CXCL13 (3 of 4) were positive in neoplastic cells. EBER was detected in one of five cases by in situ hybridization. Four cases were followed-up for 6 approximately 25 months and no recurrence or death was observed yet.

Follicular dendritic cell sarcoma is an extremely rare and should be considered as a moderately malignant tumor, and may present histological polymorphism with certain distinctive features. Immunohistochemistry is necessary in differential diagnosis to distinguish from other tumors.