[Plexiform fibrohistiocytic tumor. Histology, immunohistology and ultrastructure].

An example of a plexiform fibrohistiocytic tumour (PFT) is presented for the first time in the German-language literature. The diagnostic criteria for this rare soft-tissue neoplasm of childhood and young adulthood, which is mostly subcutaneous in location and has a tendency to recur, include the plexiform structure which gives it its name, extensive siderin deposits and numerous osteoclast-like giant cells. The development of the tumour described here, which occurred in the field of radiation of a malignant haemangiopericytoma excised 7 years previously, indicates the possibility of induction of PFT by radiation.