Dendritic cell sarcoma of the oral cavity.

Sarcomas derived from immune accessory cells are uncommon malignancies, most of them occurring in lymph nodes while extra nodal sites are very rarely affected. Based on the immune profile, the cells that give origin to these neoplasms are currently divided in: follicular dendritic cell (FDC), interdigitating dendritic cell (IDC), indeterminate cell and Langerhans cell. A case of a dendritic cell sarcoma arising in the alveolar ridge mucosa in a 50-year-old female is reported here. The lesion presented as a nodular mass without defined borders and covered by reddish mucosa. Histologically, the tumour was composed of spindle-shaped cells with large nuclei and abundant cytoplasm, arranged in variable patterns as storiform and whorled and revealing interspersed lymphocytes. No capsule could be seen and the neoplasm extended up to the lining epithelium. Immunohistochemically, the spindle cells were positive for vimentin, S-100 protein, CD1a, factor XIIIa and focally to smooth-muscle actin, but were negative for CD21, CD35, CD23 and caldesmon--all markers of follicular dendritic cells. In conclusion, the present case has morphologic pattern of dendritic cell sarcoma and the immunophenotype is compatible with IDC cells or with intermediate dendritic cells and demonstrates the overlap of features among these entities.