MALIGNANT FIBROUS HISTIOCYTOMA - HISTOMORPHOLOGICAL PATTERN OR TUMOR TYPE

During the past years MFH has obviously been used as a diagnostic wast e basket for hard to classify tumours of all Kinds. Immunohistochemist ry revealed insights into cellular differentiation of neoplastic proli ferations, also raising new questions because of unexpected antigen ex pression, as, for instance, cytokeratins in MFH. Thus, a number of tum ours originally diagnosed as MFH could be reclassified, ie. as leiomyo sarcoma, melanoma or anaplastic carcinoma. Nevertheless, there remain a certain number of sarcomas which lack any evidence of special cellul ar differentiation. These proliferations of primitive mesenchymal or f ibroblastic cells, often with a typical histological, storiform patter n, qualify as MFH. Using these strict criteria, the diagnosis of MFH w ill become rarer though not obsolete (like hemaugioperizytoma years ag o!).