Extranodal follicular dendritic cell sarcoma.

Extranodal follicular dendritic cell sarcoma is a rare tumor of follicular dendritic cells that can occur in a wide variety of sites. Although fairly well characterized histologically, with a distinct immunophenotype, it remains under-recognized, with as many as one third of cases initially misdiagnosed. This is often due to a failure to consider the entity. Patients with this tumor may have a worse prognosis than originally described. Prompted by a recent case at our institution, we briefly review the clinical features, etiology, histologic, and cytologic appearance of the tumor, as well as the ancillary studies useful in resolving diagnostic issues, primarily in an attempt to increase recognition of this rare neoplasm.