Follicular Dendritic Cell Sarcoma Involving Tonsillar Tissue

Siba El Hussein, MD
2 min readSep 11, 2021

Lessons from the Friday Unknowns

Histologic examination shows irregular fragments of soft tissue with extensive involvement by neoplastic large spindle cells.

Some with epithelioid morphology arranged in a storiform pattern, with scant to moderate cytoplasm & irregular nuclei.

Scattered mature lymphocytes in the background.

Rare mitoses and karyorrhectic bodies identified. Scattered large multinucleated giant cells are present.

Immunohistochemical stains show that the neoplastic cells are brightly positive for the provided CD21, and CD23. The neoplastic cells were negative for CD3, CD20, CD68, and S100.

These findings are supportive of the diagnosis of follicular dendritic cell sarcoma (FDCS). In contrast to other sarcomas, FDCS are characterized by the presence of scattered background lymphocytes, which could be a helpful hint to making this diagnosis.

Link to digital slides:| Slides labeled case 1

Link to similar cases: | Slides labeled case 1 | | Slides labeled case 4 |

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Siba El Hussein, MD

Hematopathology | Cytopathology | Molecular pathology | Digital pathology | Data science | Machine learning