YO30 - Follicular dendritic cell sarcoma of the tonsil- a multimodality approach

Case summary

A 53-year-old man presented with an 11-month history of a painless neck mass. On examination, he had a 10 x 5 cm mass at the left carotid triangle, and a fungating mass at the left tonsillar fossa, which on CT scan was 3.2 x 2.2 cm and invading into the parapharyngeal space.

Biopsy revealed an undifferentiated malignancy. Immunohistochemistry was negative for CK, LCA, EMA, synaptophysin, chromogranin and 34beta-E12, positive for vimentin and focally positive for S-100, favoring malignant melanoma. However, both HMB-45 and melan-A were negative, leading to a classification of undifferentiated sarcoma.

Chest and abdominal CT scan were negative for distant metastases. The tumor was deemed unresectable due to its close attachment to the great vessels, hence a sequential chemoradiation approach was pursued. He underwent six cycles of doxorubicin (60 mg/m²), resulting in 80% tumor regression. Unfortunately, he was lost to follow-up and was unable to undergo radiotherapy. He returned eight months later with re-enlargement of the neck mass to 6 x 5 cm. He remained free of distant metastases, and underwent two cycles of dacarbazine (250 mg/m², day 1-5), which did not confer any response.

The indolent behavior of the tumor prompted pathological re-evaluation. Further staining showed diffuse positivity for CD21 and negative for CD1A and CD34, consistent with follicular dendritic cell sarcoma. The patient underwent three cycles of gemcitabine (1000 mg/m², day 1 and 8) plus docetaxel (75 mg/m², day 1), resulting in 50% tumor regression. This allowed dissection of level IB – V lymph nodes, which found disease in 10/23 nodes. He subsequently underwent adjuvant radiotherapy for the neck and primary radiotherapy for the tonsillar mass, with weekly gemcitabine (400 mg/m²) as a radiosensitizer. Evaluation three months post-treatment did not show any sign of disease progression.

Follicular dendritic cell sarcoma is very rare, accounting for <0.4% of soft tissue sarcomas. Only 60 cases of tonsillar occurrence have been reported in literature. Tonsillectomy is sufficient in most cases. For our patient, a trimodality approach done due to the presence of high risk features (R2 resection, LN involvement, tumor recurrence) provided good disease control.

Clinical trial identification

Editorial acknowledgement