Objective To study the clinical and pathologic features as well as the differential diagnosis of Castleman disease. Methods Histological appearances and immunohistochemisty and gene rearrangement analysis were applied to analyze 7 cases of Casteman disease with review of literatures. Results 5 in 7 cases of Castleman diseases were hyaline-vascular type or angiofollicular, which showed small follicles scattered in a mass of lymphoid tissue. The follicles showed marked vascular proliferation and hyalinization of their abnormal germinal centers. The apearance corresponded to that of progressively transformed germinal centers. Many of the large cells with vesicular nuclei presented in the hyaline center were follicular dentritic cells. There was a tight concentric laying of lymphocytes at the periphery of follicles (corresponding to the mantle zone), resulting in an onion-skin appearance. The interfollicular stroma was also prominent, with numerous hyperplastic vessles of the postcapillary venule type and an admixture of lymphocyte, plasma cells and eosinophls. Sinuses were characteristically absent. The other 2 cases were plasma cell type that characterized by diffuse plasma cell proliferation in the interfollicular tissue. The hyaline-vascular changes in the follicles were inconspicuous or absent; instead, one often encountered in the center of these follicles a deposition of an amorphous acidophilic material that probably contained fibrin and immune complexs. One case of Castleman disease of plasma cell type showed significant lymphocytic proliferation. Restricted expression of k chain and gene arrenagement showed clonal rearrangement of immunoglobulin genes, suggesting it had evolved into B cell lymphoma. Conclusions Castleman disease is a special giant lymph node hyperplasia, which can occur at any age. Differential disgnosis of it includes reactive follicular hyperplasia and lymphoma, and special attention should be paid for cases with probable malignant transformation.