Multiple extranodal follicular dendritic cell tumors initially presenting in the soft tissue in the chest wall

A follicular dendritic cell (FDC) tumor that involved the soft tissue of the chest wall, liver and thyroid was reported in a 72-year-old Japanese man. A biopsy specimen from the chest wall showed an uncommon malignant soft-tissue tumor. No distinct immunohistochemical reactions were found. The patient died 1 year after the initial presentation. No definite diagnosis was given until autopsy was performed. Upon autopsy, each tumor was well-circumscribed and a solid tan-gray color on cut section. Microscopically, the tumor cells were composed of oval to spindle cells arranged in a short fascicular growth pattern. The autopsy specimen from the soft tissue of the chest wall had a strong reaction for CD21/CD35 and clusterin, a new FDC marker, whereas the biopsy specimen had an undistinct reaction for CD21/CD35 and a weak reaction for clusterin. FDC makers assisted in this diagnosis, especially with the autopsy specimen. In conclusion, it was difficult to diagnose an FDC tumor because of the particular tumor sites involved, lack of characteristic microscopic features, and because of aggressive tumor behavior.