Novel Diagnostic Scheme for Follicular Dendritic Cell Neoplasm: Clinicopathologic Analysis of 146 Cases.

Follicular dendritic cell neoplasm(FDCN), a rare tumor exhibiting a broad histopathological spectrum and unpredictable biologic behavior, has been classified into follicular dendritic cell tumor(FDCT) and follicular dendritic cell sarcoma(FDCS) regarded as borderline lesion and malignant tumor, respectively, by World Health Organization. But still no definite diagnostic criteria distinguishing FDCT from FDCS was established. Here in, as an approach to the differential diagnostic criteria, we performed clinicopathological analysis for 146 cases of FDCN, documented in English literature from January 1986 to May 2006. Through PubMED search with key words of FDC or dendritic cell tumor, we collected and reviewed 73 articles out of more than six thousands candidates, which contained 146 FDCNs with clinicopathological informations. We analyzed the carefully selected cases with parameters including age, gender, tumor location, tumor size, tumor margin, EBV association, mitosis, nuclear atypism, hemorrhage, necrosis and Castleman’s disease association. Recurrence, metastasis and death of disease were referred as event. Kaplan-Meier model was used for overall event-free survival analysis and the log-rank test was used to assess statistical significance.

Mitotic Index (MI, ≥ 5/10HPF vs <5/10HPF, P=0.0182) and tumor location (intraabdominal vs extraabdominal, P=0.007) showed significant association with event-free survival. But the other parameters have failed to achieve statistical significance as predictors of adverse events. For proposing diagnostic scheme, the risk groups were designated as follows: high risk group(n=7), MI ≥ 5/10HPF and intraabdominal; low risk group(n=26), MI <5/10HPF and extraabdominal; intermediate risk group(n=35), all others. These three risk groups had distinctly different median event-free survivals, 11 months, 24 months and 96 months for high, intermediate and low risk groups, respectively. And each group showed significantly different overall event-free survivals(P=0.0007). In conclusion, this novel diagnostic scheme might be a useful tool for predicting biologic behavior of FDCN.