Malignant fibrous histiocytoma. A tumor of facultative histiocytes showing mesenchymal differentiation in cultured cell lines

Abstract

The histogenesis of malignant fibrous histiocytoma (MFH) is controversial. To elucidate the cellular origin and characteristics of this neoplasm, the authors analyzed cell lines grown from 17 patients (15 soft tissue MFH and 2 bone MFH) by using light and electron microscopy, immunocytochemistry, enzyme cytochemistry, and functional tests for receptors for the Fc portion of immunoglobulin (Fc receptors) and immunophagocytosis. Each culture exhibited a storiform/pleomorphic pattern with mixed cellular populations consisting of spindle cells, polygonal cells, and bizarre giant cells; these morphologic features corresponded to the histologio characteristics of the primary tumors. The cells in each MFH line displayed histiocytic functional markers such as lysosomal enzymes, Fc receptors, and immunophagocytosis. However, these cells differed from monocyte‐derived macrophages (histiocytes) in immunoreactivity; the MFH cells expressed a mesenchymal antigen (FU3) distributed among perivascular cells and fibroblasts but demonstrated no positive reactions with Leu‐M1 (CD15) and Leu‐M3 (CD14), which recognize the cells of the monocyte‐macrophage lineage. In conclusion, these findings suggest that MFH is not a tumor of true histiocytes but of facultative histiocytes showing mesenchymal differentiation in vitro. Chromosomal analysis performed in one MFH line demonstrated abnormal karyotypes; the modal chromosome number was 58, with 5 marker chromosomes.

The Rise and Fall of Malignant Fibrous Histiocytoma

“…More critical histochemical, immunohistochemical, and ultrastructural studies of cases of so-called MFH, notably the classic storiform-pleomorphic subtype, also found that neoplastic histiocytes or ''facultative fibroblasts'' are not present in these neoplasms [42][43][44][45][46][47][48][49]. McHugh and Miettinen [47] found that the so-called histiocyte-specific marker KP1 (CD68), previously reported to indicate the presence of histiocytic tumor cells in MFH [50], is found in a variety of soft tissue tumors as well as melanomas and carcinomas.…”

An approach to pleomorphic sarcomas: can we subclassify, and does it matter?

“…With the advent of immunohistochemistry and the accessibility of numerous monoclonal antibodies directed against various structural proteins of specific cell types, the phenotype of this tumor was shown to be more closely aligned with a fibroblast than a histiocyte. [3][4][5][6] Furthermore, many, but not all, lesions labeled as 'malignant fibrous histiocytoma' could, upon close scrutiny, be subclassified as lineage-specific sarcomas, an observation that led some to question the existence of MFH as a distinct entity. 7 The extent to which such lesions can be subclassified as sarcomas of alternative type is, in large part, dependent on definitional criteria and the number of ancillary studies a pathologist is willing to bring to bear on the evaluation of a pleomorphic sarcoma.…”

Simultaneous occurrence of malignant fibrous histiocytoma and hepatocellular carcinoma in cirrhotic liver: A case report

“…Similar findings have been reported in cases of primary hepatic MFH [9] . Although MFH does not originate from histiocytes [11] and although malignant neoplasms other than MFH may express histiocytic markers [12] , positive immunohistochemical staining for histiocytic markers in the absence of other markers for specific lineages raise the possibility of MFH in primary hepatic spindle cell tumors. To our knowledge, our case is the first described case with primary hepatic MFH arising in a cirrhotic liver.…”