[Follicular dendritic cell sarcoma in a lymph node].

We report the case of a 39 years old man who presented with a rapidly enlarging, painless mass in his left side of the neck. The mass was excised and turned out to be a lymph node. Histologically, it showed a proliferation of oval to spindle cells growing in sheets and fascicles, occasionally forming a storiform pattern. Tumor cells showed large nuclei, dispersed chromatin and small evident nucleoli. Neoplastic cells were positive for immunohistochemical markers vimentin, CD 68, CD 21, CD 35 and R 4/23. Ultrastructural examination showed long cytoplasmatic processes joined by desmosomes. The patient was treated with local radiotherapy and is alive and well 18 months after the excision. Follicular dendritic cell sarcoma is a very unusual tumor that merits wider recognition.