[Immunohistochemical studies in the differential diagnosis of malignant fibrous histiocytoma].

Malignant fibrous histiocytomas (MFH) belong to the most frequent soft tissue tumours in adults and have to be discriminated from other tumours with similar morphology. Various tumour markers aid the differential diagnosis. Twenty cases of MFH were studied immunohistochemically using antibodies to vimentin, TPA, desmin, lysozyme, alpha 1-antitrypsin, alpha 1-antichymotrypsin, S-100 protein, neurone-specific enolase (NSE), laminin, fibronectin and ferritin. Vimentin and lysozyme were found in the tumour cells of all, alpha 1-antitrypsin of 18, alpha 1-antichymotrypsin of 19, fibronectin of 16 and ferritin of 12 cases. Antibodies of TPA, desmin, S-100 protein, NSE and laminin did not reveal positive immunoreactivity. Exclusion of spindle-cell carcinoma can be made by positive vimentin and negative TPA reactivity, of melanoma by negative S-100 reactivity, and of leio- and rhabdomyosarcoma by lack of desmin immunoreactivity. Schwannomas contain S-100 protein, but lack lysozyme, alpha 1-antitrypsin, alpha 1-antichymotrypsin and fibronectin. Pleomorphic liposarcomas cannot be distinguished from MFH on the basis of immunohistochemical staining. Vimentin, alpha 1-antitrypsin, alpha 1-antichymotrypsin and fibronectin can, therefore, be regarded as useful markers in the differential diagnosis of MFH.