Clinicopathologic analysis of four cases of extranodal follicular dendritic cell sarcoma

Abstract

Objective To study the clinicopathoiogic features of four cases of extranodal follicular dendritic cell sarcoma(FDCS). Methods Four cases of FDCS were examined by histological and immunohistochemistry and in situ hybridization for Epstein-Barr virus (EBV)-encoded RNA, and the related literatures were reviewed. Results Microscopically, the neoplastic cells were spindle-shaped or ovoid with pale-stained cytoplasm, indistinct cell borders, granular chromatin, distinct small nucleoli. There were varied growth patterns in the tumour, such as fascicular, circular whorls and storiform, and abundant with intermixed small lymphocytes. There scattered multinucleated giant cells and perivascular cuffing phenomenon. There were rare mitoses. The neoplastic cells were positive for one or more of the follicular dendritic markers such as CD21, CD23 and CD35. It was variably positive for CD68, Vimentin, LCA and S-100. Staining for CD20, CD3 and CD1α were negative. Ki-67 labeling ranged from 10 %-20 %. The neoplastic cells were negative for Epstein-Barrvirus (EBV)-encoded RNA. Conclusion FDCS is a rare low-grade malignant tumor with varied growth pattern. The diagnosis should be confirmed by immunohistochemical staining. It is important to recognize its morphological characteristics to avoid confusion with other similar lesions, such as gastrointestinal stromal tumour, inflammatory pseudotumor, interdigitaing dendtritic cell sarcoma, malignant histiocytoma, lymphoepithelial carcinoma, diffuse large B-cell lymphoma, and malignant melanoma. Key words: Follicular dendritic cell sarcoma; lmmunohistochemistry; Diagnosis, differential; Insitu hybridization