No abstract

We have studied the possible origin of histiocytic cells, present in fibrous histiocytomas (MFH) by using immunohistochemistry to demonstrate lysozyme, alpha 1-antitrypsin, alpha 1-antichymotrypsin and receptors for peanut and soy bean agglutinin in tumour cells of MFH compared with their presence in tumour cells of malignant histiocytosis (MH) ('true' histiocytic lymphoma, 'true' histiocytic sarcoma). We included in this study a number of other soft tissue tumours (STT). Lysozyme was detected in half of the cases of malignant histiocytosis (n = 16) but in only two out of 77 MFH. alpha 1-Antitrypsin and alpha 1-antichymotrypsin usually occurred together although the latter was seen in more cases. Both markers were present in majority of cases of MH whereas they were detected in a minority of cases of MFH. MFH cases of the storiform subtype were less frequently stained than the pleomorphic or giant cell subtypes. Receptors for peanut or soy bean agglutinin were detected in nearly all MH cases, whereas their presence was only detected in a small number of MFH. Lysozyme was not detectable in other STT. alpha 1-Antitrypsin and alpha 1-antichymotrypsin were uncommonly present in other STT, except in osteosarcoma and rhabdomyosarcoma. These markers therefore have a limited value as indicators of a possible histiocytic origin of MFH. Lectins showed weak affinity for other STT. In accordance with others, we therefore conclude that the progenitor cell of MFH has to be sought within the undifferentiated mesenchymal cells and that histiocytes themselves probably do not give rise to MFH.

No abstract

We have investigated the phenotype and ultrastructure of tumour cells from two cell lines each derived from a malignant fibrous histiocytoma (MFH) as a means of studying the histogenesis of this group of tumours. The first MFH (MFH-I) was of the pleomorphic subtype, with a predominantly histiocytic appearance, the second was of the pleomorphic subtype associated with myxoid and storiform areas (MFH-II). In vitro tumour cells from both neoplasms showed aberrant growth properties. Xenografts in nude mice from both neoplasms showed a similar histology to that of the original tumour. Both tumours showed hyaluronidase sensitive alcian blue staining. Phenotypic studies of the two cell lines and of the tumour tissues demonstrated that the cells differed in the presence of collagen types I and III. They did not show evidence of histiocytic, endothelial, leiomyoblastic, rhabdomyoblastic, lipoblastic of schwannian origin. Ultrastructurally, the two cell lines were found to be different. In vitro and in xenografts the cell type of MFH-I resembled a primitive mesenchymal cell. Whereas that of MFH-II resembled a fibroblast-like cell. We concluded that the group of MFH is heterogeneous and is probably derived from more than one progenitor cell.