Malignant fibrous histiocytoma of bone. Light microscopic and electron microscopic examination of four cases

How is the mutational status for tumor suppressors p53 and p16(INK4A) in MFH of the bone?

Both tumor suppressor genes p53 and p16(INK4A) play a crucial role in the control of cell cycle and tumor development. In this study 19 malignant fibrous histiocytomas of the bone (MFH-b), a very rare sarcoma entity, were investigated for mutations in p53 and p16 genes by a PCR-SSCP-sequencing analysis. In the tumor samples two p53 mutations and two polymorphisms (one in the p53 gene and one in the p16 gene) were found. The occurrence rate for p53 mutations and the absence of p16 mutations in MFH-b are comparable to the findings for MFH of soft tissues (MFH-st) and osteosarcomas, suggesting that p53 rather than p16 may play a role in tumorigenesis of MFH-b.

Establishment and characterization of a fibrous histiocytoma cell line (NMSG 10) derived from a malignant fibrous histiocytoma

A fibrous histiocytoma cell line, NMSG 10, was derived from a malignant fibrous histiocytoma (MFH), of human tibia, and its characteristics were examined. MFH was a pleomorphic subtype associated with myxoid and storiform areas. Primary culture revealed a mixture of histiocyte-like cells, fibroblast-like cells and giant cells, but fibroblast-like cells became the major population after several passages in vitro. In addition, NMSG 10 produced a large amount of viscous material which stained with alcian blue and was digested by hyaluronidase. Thus, this viscous material was a single component of glycosaminoglycans: hyaluronic acid (HA). The cells were spindle-shaped with well-developed cytoplasmic organelles and collagenous filaments, and a colloid iron-positive substance was observed in intercellular spaces. In scid mice, the mixed populations of neoplastic cells appeared similar in histology to that of the original tumor. These findings indicated that NMSG 10 expresses the unique properties of MFH, and should therefore be useful in studies on the biological behavior, and especially the presence of HA in MFH.

Fibroblast and myofibroblast participation in malignant fibrous histiocytoma (MFH) of bone. Ultrastructural study of eight cases with immunohistochemical support

Eight malignant fibrous histiocytomas (MFH) of bone were studied with immunohistochemistry and electron microscopy. Ultrastructurally, fibroblasts and myofibroblasts were the main tumor cells in four cases and abundant in two other cases; these cells showed immunohistochemical positivity to alpha 1-antitrypsin, vimentin and anti-muscle antigen (HHF 35). Moreover, histiocytic-like tumor cells were electron-microscopically detected in four cases, being the main tumor cell type in two of the cases; immunohistochemically these cells expressed positivity to alpha-1-antichymotrypsin (A1ACT), alpha-1-antitrypsin (A1AT) and vimentin. Present results confirm the cellular heterogeneity of MFH of bone, in which fibroblasts and myofibroblasts transformed cells play a histogenetical role, suggesting the existence of close links with classic fibrosarcoma of bone.

Flow cytometric DNA analysis of bone tumors

Flow cytometric DNA analysis was performed in a total of 203 bone tumors, benign and malignant. In more than 80% of cases the material studied was paraffin-embedded tumor tissue, mainly from the archives of the Bone Tumor Registry of Westphalia in Münster. Compared with ethanol-fixed fresh tumor samples, the variation coefficient in DNA histograms of the stored material was increased by a factor of 1.2-1.5, which means that resolution was decreased and that, in many cases, accurate cell cycle analysis was not feasible. However, the results of cell cycle analysis in bone tumors, even if performed on optimally fixed specimens, have to be evaluated with caution and full reference to the corresponding histological slides, since these histograms are apt to show various superpositions from the inflammatory infiltrate. The assessment of DNA ploidy is unimpaired if, in agreement with most researchers today, deviations smaller than +/- 10% from the diploid standard are still defined as DNA diploid, peridiploid, or pseudodiploid. The coefficient of variation should be kept as low as possible. If it is between 10% and 15%, the near-diploid stemlines with DNA indices of 0.9 or 1.1 may be hard to delineate. On account of the particularly marked regressive changes, the resolution of DNA histograms was most strongly impaired in chondromatous tumors, whereas it was mostly excellent in highly cellular viable tumor tissue, such as that from Ewing's sarcoma or osteoblastoma. On the whole, there was a distinct correlation between DNA ploidy and the biological behavior of bone tumors (Table 8). The highest rates of DNA aneuploidy were found in highly malignant OSs (18/21) and FSs (14/16), thus reflecting their poor prognosis. Of six juxtacortical OSs, three well-differentiated parosteal OSs and two periosteal OSs were DNA diploid, whereas one highly malignant surface OS and five highly malignant extraskeletal OSs, all DNA aneuploid, corresponded fully to the medullary OSs. Judging by preliminary results, adjuvant preoperative chemotherapy (COSS 80/82: Bösing et al. 1987) may reduce the rate of DNA aneuploidy and, consequently, of stem cell heterogeneity in general. A selective destruction of those stemlines that respond particularly to chemotherapy appears probable. In contrast to their high malignancy, Ewing's sarcomas showed an unexpectedly low proportion of DNA aneuploid stemlines (14/24). The comparatively favorable prognosis of MFH of bone is reflected in a lower rate of aneuploidies (2/10), which is also rather low (probably too low) when compared to our own data from soft tissue MFH (9/19).(ABSTRACT TRUNCATED AT 400 WORDS)

The cytogenesis of macrophages and osteoclast-like giant cells in bone tumors with special emphasis on the so-called fibrohistiocytic tumors

Recent investigations have suggested that osteoclasts and osteoblasts belong to different cell systems: osteoclasts originate from hemopoietic stem cells, most probably via precursors of the mononuclear phagocyte system. Osteoblasts, however, arise from local mesenchyme. The present classification of bone tumors issued by the WHO, however, is still based on the assumption of osteoclasts and osteoblasts being merely different manifestations or differentiations of the same basic cell type. Consequently, histiocytes or macrophages as well as osteoclast-like giant cells are interpreted in most bone tumors as an autochthonous component of the tumor. In the present study, this theory is contradicted by histological immunohistological, electron microscopic, and autoradiographic-electron microscopic results on a larger number of osteosarcomas, chondromas, chondrosarcomas, chondroblastomas, aneurysmal bone cysts, giant cell tumors of bone, malignant fibrous histiocytomas, fibrosarcomas, desmoplastic fibromas, Ewing's sarcomas, fibrous dysplasias, nonossifying fibromas, and malignant hemangioenkdotheliomas of bone. In order to elucidate the role of macrophages and osteoclast-like giant cells, different monoclonal antibodies were applied to bone tumor specimens as markers of mononuclear macrophages and giant cells. The concept of what is called fibrohistiocytic tumors should be reconsidered. Immunohistological studies have shown that in malignant fibrous histiocytoma as well as in giant cell tumors of bone only a certain portion of macrophages will react with the highly specific antibodies, whereas the majority of tumor cells are negative. This finding alone suggests that the infiltration of macrophages is a reactive phenomenon. It is in agreement with earlier autoradiographic and electron microscopic investigations on giant cell tumors of bone, confirming that only the fibroblast-like tumors are actually proliferating. These data were verified in the present study with the aid of double labeling immunohistological techniques, using antibodies against mature tissue macrophages and others against a proliferation-associated nuclear antigen. Only the fibroblast-like cells, which do not react with the macrophage-specific antibody, will express the proliferation-associated nuclear antigen. Analogous results were obtained in malignant fibrous histiocytoma. We may infer from these results that the majority of these tumors must be neoplasms of local mesenchyme, mostly in fibroblastic differentiation, while the considerable number of macrophages is seen as a reactive phenomenon.(ABSTRACT TRUNCATED AT 400 WORDS)

Cellular heterogeneity. Explanation for changing of tumor phenotype and biologic behavior in soft tissue sarcomas

Many human soft tissue sarcomas are known to show variable structures in a given tumor and to be able of changing the histological feature during the course of the disease. These facts prompted an experimental study in order to ascertain if by use of long-term cultures of an established rat fibrosarcoma cell line (RFS) in respective inoculation tumors a histological picture different from the original fibrosarcoma could be produced. It was found that inoculation tumors generated by later subcultures partly corresponded to tumors with features of malignant histiocytomas and malignant fibrous histiocytomas. In a further experiment we attempted to initiate metastatic dissemination of a primarily non-metastasizing xenotransplanted RFS sarcoma in nude mice. By repeated diminution operations comparable to inadequate tumor surgery in human metastasis formation in lung parenchyme was attained. Taking into account cellular heterogeneity as basically responsible for the phenomena observed, different causal aspects concerning the experimental results are discussed. We deduce from our findings that the concept of histogenetic classification of soft tissue sarcomas should be replaced by an interpretation according to the actual differentiation. This also applies to malignant fibrous histiocytomas which are at least in part mesenchymal tumors and not descendants of mononuclear phagocytic cells and may originate by a dedifferentiation process of otherwise defined sarcoma types.

Biological characterization of human bone tumors. X. The proliferation behavior of macrophages as compared to fibroblastic cells in malignant fibrous histiocytoma and giant cell tumor of bone

Seven giant cell tumors of bone and four malignant fibrous histiocytomas were studied immunohistochemically with different monoclonal antibodies to the mononuclear phagocyte system (MPS), to HLA-DR antigens, and to a proliferation-associated nuclear antigen (KI-67), in order to clarify the role of macrophages in these tumors. A part of the mononuclear cells stained positive with antibodies against the MPS. Antibody 25-F-9 against mature tissue macrophages showed the strongest reaction. The osteoclast-like giant cells also stained positive with this antibody. Fibroblast-like stromal cells, however, showed negative reactions to all antibodies against MPS cells. A double-labeling immunohistological technique was used to detect the proliferating cell population in these tumors. The fibroblast-like cells that were negative for MPS markers, were positively labeled with the monoclonal antibody Ki-67 against a proliferation-associated nuclear antigen, whereas a negative reaction to Ki-67 was seen in cells positive with antibodies to the MPS. These results support the concept that macrophages are a reactive population in these tumors, whereas the fibroblast-like mesenchymal cells are the proliferating tumor cells.

Malignant fibrous histiocytoma of the pericranium: case report

Malignant fibrous histiocytoma only infrequently arises from structures of the head and neck. When it does, it most often originates in facial structures, particularly the maxilla. This case report details a malignant fibrous histiocytoma arising from the pericranium, and presenting clinically as a large indurated frontal calvarial mass. A CT scan showed its origin to be from the pericranium and demonstrated its intracranial extension. Radical excision presented a surgical challenge because of the extensiveness of the lesion. Yet, combined with post-operative teletherapy, a favourable outcome was obtained.

Alteration in osteoblast cell number and cell activity in the presence of invading malignant fibrous histiocytoma

Correct prediction of tumor behavior and interpretation of local factors in the tumor microenvironment rely in part upon accurate determination of tissue changes after tumor invasion. The authors examined local bone changes in primary malignant fibrous histiocytoma (MFH) of bone in a 59-year-old woman. Three noninvolved and three tumor-involved sites were evaluated by quantitative determinations of bone structural and dynamic features. Compared to noninvolved sites, tumor-involved bone was characterized by significantly increased osteoblast index (89.4 +/- 15.6 [mean +/- SEM] versus 7.3 +/- 6.0, P = 0.008), percent osteoid area (12.1 +/- 2.7 versus 1.2 +/- 0.5, P = 0.02), percent of trabecular surface covered by osteoid (70.0 +/- 6.0 versus 14.5 +/- 4.8, P = 0.002), and percent osteoid lined by osteoblasts (36.4 +/- 3.6 versus 3.7 +/- 3.0, P = 0.002). Bone 7.8 mm distant from invading tumor cells showed features characteristic of noninvolved sites, whereas bone completely surrounded by tumor showed markedly decreased osteoblast features. Osteoblast function also was affected by tumor; the amount of matrix laid down per day bore a significant positive correlation with the osteoblast index. These data indicate the following: distinctive bone morphologic changes occur in situ during invasion by MFH; changes affect aspects of bone formation but not resorption during invasion; both osteoblast number and osteoblast activity are significantly altered; and changes are local in nature and probably reflect the osteoblast response to local tumor factor(s) and are dependent upon the extent of tumor invasion.

Experimentally induced metastases of malignant fibrous histiocytomas xenotransplanted into nude mice from an established sarcoma cell line (RFS)

An experimental approach for inducing metastases from xenotransplanted malignant fibrous histiocytomas in nude mice is presented. Malignant fibrous histiocytomas were generated by inoculation of an established cell line (RFS) in the back of 16 nude mice. 7 nude mice were subjected to diminution operations carried out twice and three times, respectively, 6 out of these animals developed metastases, whereas no metastases were found in the inoperated control group (9 mice). The metastasis formation is explained by sarcoma heterogeneity, some factors which might contribute to the phenomenon of tumor dissemination are discussed.

Malignant fibrous histiocytoma induced by intra-articular injection of 9,10-dimethyl-1,2-benzanthracene in the rat. Pathological and enzyme histochemical studies

Malignant fibrous histiocytoma (MFH) was produced by injection of 9,10-dimethyl-1,2-benzanthracene (DMBA) into the rat knee joint. The tumor was observed in or around the knee in nearly all the animals 13 to 36 weeks after the initial DMBA administration. Histologically, these lesions were of the storiform-pleomorphic type (39/58, 67.2%), myxoid type (9/58, 15.5%), or giant cell type (8/58, 13.8%). Six cell types reported in human MFH were confirmed and phagocytosis of 0.81-micron latex particles by histiocyte-like cells was noted by electron microscopic examination. Acid phosphatase, beta-glucuronidase, and alpha-naphthyl acetate esterase were positive in enzyme histochemical examinations. Acid phosphatase activity was electron microscopically noted primarily in the lysosomes and the Golgi apparatus of the histiocyte-like cells. Cells from the storiform-pleomorphic (M1) and myxoid (M2) type tumors were serially transplanted subcutaneously in the back of the rats, and are now at the thirtieth and fortieth passage, respectively. They also were studied by enzyme histochemical and electron microscopic techniques. Our observations suggested an undifferentiated mesenchymal cell origin of MFH. Transplantable MFH can be produced in rats by intra-articular injection of DMBA, and lesions thus produced are a useful experimental model for the investigation of the histogenesis and the effect of chemotherapy of MFH.

Malignant fibrous histiocytoma of bone. A review of 13 cases and an ultrastructural study

Observations on 13 patients with primary malignant fibrous histiocytoma of bone were reported. Included were nine male and four female patients, ranging in age from 6 to 81 years (mean, 44.8 years). Pain was the most common complaint. The interval from the first symptom to the initial treatment varied from 2 months to 20 years. Seven tumors arose in the knee region. Roentgenologically, most of the lesions presented with an osteolytic and destructive appearance. Histologically, highly variable morphologic features existed. The storiform-pleomorphic pattern was found in every tumor, although it was not necessarily pathognomonic for malignant fibrous histiocytoma of bone. Surgery, radical or incomplete, was the primary treatment for all but one patient. Lymph node metastasis was present in three. Five patients died of the disease from 3 to 79 months after the diagnosis (mean, 28 months), all exhibiting metastasis to the lung. Gaucher's body-like structure demonstrated in the electron microscopic study shows the histiocytic quality of malignant fibrous histiocytoma of bone.

Human osteogenic sarcoma: fine structure of the fibroblastic type

The fine structure of representative regions of nine fibroblastic osteogenic sarcomas was studied. As judged by light microscopic criteria, the tumors represented both highly malignant (grades 3-4) and less malignant (grade 2) varieties. By electron microscopy, six basic cell types were found in the selected regions (fibroblastlike, histiocytelike, and myofibroblastlike cells, along with xanthoma cells, multinucleated giant cells, and undifferentiated cells). In addition, occasional osteoblastlike cells were encountered. Fibroblastlike cells in general, and especially in grade 2 tumors, showed a fine structure, enabling differentiation from osteoblastlike cells. Multinucleated giant cells were of two morphologic types, and the fine structure appeared to be related to the malignancy potential and differentiation of the tumors. Many multinucleated giant cells in grade 2 tumors had a ruffled border and appeared to be highly active in digestive events (especially phagocytosis of whole cells and portions of cells). Accumulation of variable amounts of lipid in droplet form was common in the various types of cells present in the tissues. The observations were discussed with particular emphasis on the interrelationships and functional roles of the cells.

Experimental tumors with features of malignant histiocytomas. Morphological studies on neoplasms produced by inoculation of an established macrophage-like cell line (WEHI-3)

Soft tissue malignant histiocytomas are thought to be a histologic variant of malignant fibrous histiocytomas. By means of an established macrophage-like cell line (WEHI-3) we produced experimental tumors with light microscopic features of malignant histiocytomas. In spite of repeated subculturing of WEHI-3 cells and their derivatives the 6 tumor generations received by cell transplantations were remarkably constant in regard of their light and electron microscopic morphology. This was in contrast to preceding experiments with an established fibrosarcoma cell line. Electron microscopically they were never to be identified in the histiocytoma-like tumors so that these neoplasms could virtually not be considered as members of the malignant fibrous histiocytoma group. Our results support the idea that malignant fibrous histiocytomas and malignant histiocytomas of the soft tissues arise from undifferentiated mesenchymal cells and emphasize that monocyte-derived histiocytic tumors may appear as soft tissue histiocytomas although they are more related to malignant histiocytosis.