Intraoral infantile hemangiopericytoma: literature review and addition of a case.

A rapidly growing neoplasm in the buccal mucosa of a 4-month-old baby was excised. By light and electron microscopy the neoplasm had features that were similar to those described in infantile hemangiopericytoma, a rare neoplasm of vascular origin. By light microscopy the neoplasm was multilobular with highly proliferating round to spindle-shaped cells interspersed with numerous vascular spaces. Ultrastructurally, round to elongated cells with short processes, pinocytotic vesicles, reduplicated basal lamina, and basal lamina-like material were identified. Immunohistochemically the cells were weakly positive with antibodies to vimentin, focally positive with HHF-35, a smooth-muscle cell antibody, negative with antibodies to S-100 protein, T-200, neuron-specific enolase, neurofilaments, desmin, and cytokeratins 35BH11 and 34BE12. Blood vessels were positive with Ulexeuropaeuslectin, but tumor cells were negative. Reticulin stain decorated a delicate network of fibrils surrounding tumor cells and vascular spaces. Clinically the neoplasm did not recur and the baby has been disease free for more than 26 months. The difficulty of the histologic diagnosis of this neoplasm is discussed and the literature is reviewed, with special emphasis on lesions occurring in the oral cavity.