Pleomorphic malignant fibrous histiocytoma
Overview
Malignant fibrous histiocytoma (MFH) was first described in 1964 under the name malignant fibrous xanthoma. Since that time several major variants have been identified and it has become the most commonly diagnosed of all the sarcomas of adults. Oral and maxillofacial sites are seldom involved, however, and the tumor occurs primarily in the soft tissues of the extremities and retroperitoneum
Diagnosis
The diagnostic approach of any tumor resembling MFH can be initiated by careful sampling of the tumor in quest for areas that may help identify a line of differentiation. If the initial sections are not helpful in identifying a line of differentiation, additional sampling can help reveal more differentiated areas or at least some diagnostic features that were not present in the initial sections. In a published study,21 3 retroperitoneal lesions of dedifferentiated liposarcoma were initially misdiagnosed as MFH. This was because of lack of sufficient sampling as only 2, 3, and 1 paraffin blocks were performed on the 3 cases and none showed the well-differentiated liposarcoma component. The recurrent tumors were sampled extensively (37, 58, and 40 paraffin blocks). Areas of well-differentiated liposarcoma were seen on few slides, and in 1 case the well-differentiated liposarcoma component was seen on 1 slide only. Careful and extensive sampling was substantial in these cases to identify a line of differentiation and thus avoiding the erroneous diagnosis of MFH.