Extranodal follicular dendritic cell sarcoma of the tonsil - case report of an epithelioid cell variant with osteoclastic giant cells.

Follicular dendritic cell sarcomas are rare neoplasms arising from the accessory cells of the lymph nodes, the follicular dendritic cells. They commonly occur in the lymph nodes, but have also been reported at extranodal sites (especially the tonsil). At both sites, there is usually a proliferation of spindled to ovoid cells, mimicking a mesenchymal tumor. Herein, we report a tonsillar tumor in a 50-year-old man, which was composed exclusively of large polygonal cells and numerous osteoclastic giant cells that resembled a giant cell carcinoma. The true nature of the tumor was revealed after an array of immunohistochemical stains. The patient is well 4 years after tonsillectomy.