Congenital, infiltrating giant-cell angioblastoma. A new entity?

This report describes histopathologic, immunohistologic, and ultrastructural features of a locally aggressive soft-tissue tumor present since birth in an upper extremity of an infant. Because of extensive infiltration of local structures, the lesion had to be treated by amputation. The outstanding histologic feature consisted of nodular cell clusters resembling inflammatory granulomas, often with giant, multinucleated cells. On the basis of our findings, these cellular aggregates were interpreted as distorted attempts at formation of vessels. This interpretation was strengthened by the more obviously vascular structure of the tumor in many areas. A high content of stromal cells positive for factor XIIIa and histocompatability antigen (HLA)-DR was a characteristic that the tumor shared in common with angiomatoid malignant fibrous histiocytoma. However, there were also important differences that singularize the tumor described in the present study. We could find no closely comparable precedent for a lesion with these characteristics in current treatises on infantile soft-tissue tumors.