Follicular Dendritic Cell Sarcoma of the Tonsil: A Multimodality Approach.

Follicular dendritic cell sarcoma (FDCS) accounts for < 0.4% of soft tissue sarcomas. Only 35 cases of tonsillar FDCS have been reported, and majority had localized presentation. We present a case of FDCS of the tonsil, wherein a well-coordinated trimodality approach provided good disease control in advanced disease. A 53-year-old man presented with a painless and enlarging neck mass of 11-month duration, with no other symptoms. Close examination revealed a 10 × 5 cm mass at the left carotid triangle, and a 3.2 × 2.2 cm mass at the left tonsillar fossa. Imaging revealed the tumor to be unresectable due to its attachment to the great vessels. There were no distant metastases. Biopsy and immunohistochemistry were initially deemed consistent with an undifferentiated sarcoma. Palliative chemotherapy was given using single agent doxorubicin and subsequent dacarbazine, resulting in partial response and stable disease, respectively. Pathological re-evaluation was pursued because of the uncharacteristic slow progression of the tumor, revealing diffuse positivity for CD21 and negative for CD1A and CD34, consistent with FDCS. The patient underwent three cycles of gemcitabine plus docetaxel resulting in 50% regression. This allowed dissection of level IB-V lymph nodes and subsequent radiotherapy for the neck and tonsillar mass, with weekly gemcitabine as a radiosensitizer. Evaluation 8 months post-treatment showed no signs of disease progression. Treatment-related complications included radiation dermatitis and swallowing dysfunction, which both resolved on follow-up. This case highlights the multidisciplinary management of a rare type of sarcoma in an uncommon anatomic location. Precise pathologic diagnosis is important in soft tissue sarcoma because of its therapeutic implications. For FDCS, effective response may still be achieved in the third-line setting.