Evaluation of osteonectin as a diagnostic marker of osteogenic bone tumors.

Osteonectin (ON), a 32,000-kd glycoprotein involved in the early steps of mineralization of skeletal tissue, is a recognized differentiation marker of normal osteogenic cells. The expression of ON was evaluated in vitro and in tissue sections by the polyclonal antibody bON II. In different cell cultures immunocytochemistry and molecular biology displayed a nonspecific reaction for the antibody, which showed itself to be useless for the in vitro identification of cells of the osteoblastic lineage. The diagnostic use of bON II antibody was investigated by immunohistochemistry on a series of osteogenic and nonosteogenic bone tumors. A strongly positive stain of the entire neoplastic component of osteosarcoma and osteoblastoma and a weaker stain of the mononuclear component of giant cell tumor and chondroblastoma were observed. On the other hand, stains for chondrosarcoma, Ewing's sarcoma, fibrosarcoma, malignant fibrous histiocytoma, and brown tumor from hyperparathyroidism were entirely negative. Our results indicate that ON may be helpful in the histologic diagnosis of bone tumors, particularly in differentiating small cell osteosarcoma from other small round cell tumors.     

Enzyme histochemical study on bone tumors

A total of 19 cases with bone tumors, including six osteosarcomas. three giant cell tumors of bone, one malignant fibrous histiocytoma, four nonossifying fibromas, four chondromas and one chondrosarcoma, were examined as to enzyme histochemistry; the enzymes consisted of alkaline phosphatase (ALPase), acid phosphatase (ACPase), nonspecific esterase (NSE), adenosine triphosphatase (ATPase), 5'-nucleotidase (5'-Nucl) and beta-glucuronidase (beta-Gl). Osteosarcoma was strongly positive for ALPase followed by 5'-Nucl. Giant cell tumor, malignant fibrous histiocytoma and nonossifying fibroma showed enzyme histochemistry similar to each other: multinucleated giant cells and round cells in these tumors were strongly positive for ACPase, NSE, ATPase and 5'-Nucl simulating osteoclasts and histiocytes, whereas spindle cells were positive for ATPase and 5'-Nucl in their cytoplasm and weakly positive for ACPase. Chondroma and chondrosarcoma were focally positive for ACPase and NSE; the ACPase was sensitive to tartaric acid treatment. These observations showed that ALPase activity is very characteristic to osteosarcoma, and is useful for its diagnosis. From enzyme histochemistry, giant cell tumor, malignant fibrous histiocytoma and nonossifying fibroma can be regarded as a histiocyte-derived tumor of bone in contrast to osteosarcoma and cartilaginous tumors.     

Ultrastructural features of malignant fibrous histiocytoma of bone.

Five cases of malignant fibrous histiocytoma originating in the femur and tibia, sometimes with local recurrences, are reported. Histological and clinical characteristics of this lesion were similar to those in soft tissues with the same disease. The present histiocytomas were observed by electron microscopy and shown to consist of 5 types of neoplastic cells which were regarded as undifferentiated cells, histiocyte-like cells, which were predominating, fibroblast-like cells, multinucleated giant cells and xanthomatous cells. These findings led us to confirm the existence of malignant fibrous histiocytoma originating in bone as well as in soft tissues.     

Matrix vesicles in bone tumors. Ultrastructural analysis and their significance in neoplastic bone formation.

Bone tumors were categorized into alkaline phosphatase (ALPase)-positive (2 ossifying fibromas, 1 benign osteoblastoma and 16 osteosarcomas) and negative (2 chondromas, 2 chondrosarcomas, 3 non-ossifying fibromas, 2 malignant fibrous histiocytomas and 6 giant cell tumors of bone) groups. Production and distribution of matrix vesicles (MVs) in the tumor tissues were examined to clarify their role in neoplastic bone formation. Four distinct types of MV were isolated primarily in ALPase positive bone tumors: empty, amorphous, crystalline and ruptured MVs. They were formed by budding off from the cytoplasmic projections of the osteoblastic tumor cells. The significance of differences in the production rate of MVs between ALPase-positive and negative bone tumors was investigated in view of the predominantly high production of MVs in ALPase-positive bone tumors. Many more mature MVs (crystalline and ruptured) were observed in the osteoblastic lesions of osteosarcoma than in the fibroblastic and MFH-like lesions, suggesting an intimate relationship with maturation and differentiation of the osteoblastic tumor cells. The above findings indicate that production of MVs is one of the diagnostic parameters for osteoblast-derived bone tumors, as well as ALPase activity, and that vesicle-induced mineralization is a major mineralization mechanism in neoplastic bone formation.     

Supernumerary ring chromosomes in five bone and soft tissue tumors of low or borderline malignancy

Five tumors (two myxoid malignant fibrous histiocytoma, two dermatofibrosarcoma protuberans, and one parosteal osteosarcoma) with ring chromosomes as the sole cytogenetic anomaly or as the only structural rearrangement were observed in a series of 60 karyotypically abnormal, nonlipogenic bone and soft tissue tumors (BST). All five tumors were of borderline or low malignancy. These findings support the suggestion that supernumerary ring chromosomes as the sole structural chromosomal aberration are not associated with any particular histopathologic diagnosis but may characterize a group of BST of borderline or low malignancy.     

Lysozyme and alpha 1-antitrypsin in giant-cell tumor of bone and in other lesions that contain giant cells

We performed an immunohistochemical study of 24 giant-cell tumors of bone and 30 other lesions (fibrous histiocytoma, nonossifying fibroma, and giant-cell tumor of the tendon sheath) using lysozyme and alpha 1-antitrypsin as markers for histiocytic cells. The presence of histiocytic cells in giant-cell tumors of bone is confirmed by the finding of a positive reaction for alpha 1-antitrypsin in both multinucleate giant cells and mononuclear stromal cells in some cases. It is not clear whether the positive cells are to be regarded as neoplastic or reactive and alpha 1-antitrypsin is not considered as a diagnostically useful marker for giant-cell tumor of bone. In malignant fibrous histiocytoma, too, histiocytic cells could be identified by their positive reaction for alpha 1-antitrypsin; some of these cells had the morphologic features of tumor cells. Cells with a positive reaction for lysozyme were rarely found, except in giant-cell tumors of the tendon sheath.     

Malignant fibrous histiocytoma of bone. Clinical pathology and histological diagnosis

Malignant fibrous histiocytoma of bone is a histologically well-defined tumor. Our aim is to describe five own cases and to analyze the published cases in order to demonstrate, the controversial aspects of clinical pathology. The essential histological criteria are the storiform tissue pattern and the presence of fibroblastic and histiocytic cells and giant cells. Inclusive of our cases, the total number reported stands at 196. There are features of malignant fibrous histiocytoma of bone about which there is almost general agreement: 1. The tumor occurs at all ages with an average onset from the age of 10 to the age of 50. 2. The tumor occurs in both the long and flat bones, but the main sites are the distal femur and the proximal tibia. 3. The tumor lacks any initial distinctive features in its clinical phase, but with respect to its biological behaviour, malignant fibrous histiocytoma of bone can be distinguished from osteosarcoma.     

ULTRASTRUCTURAL FEATURES OF MALIGNANT FIBROUS HISTIOCYTOMA OF BONE

Five cases of malignant fibrous histiocytoma originating in the femur and tibia, sometimes with local recurrences, are reported. Histological and clinical characteristics of this lesion were similar to those in soft tissues with the same disease. The present histiocytomas were observed by electron microscopy and shown to consist of 5 types of neoplastic cells which were regarded as undifferentiated cells, histiocyte-like cells, which were predominating, flbroblast-like cells, multinucleated giant cells and xanthomatous cells. These findings led us to confirm the existence of malignant fibrous histiocytoma originating in bone as well as in soft tissues.     

Chemically induced transplantable malignant fibrous histiocytoma of the rat. Analyses with immunohistochemistry, immunoelectron microscopy and [3H]thymidine autoradiography

Malignant fibrous histiocytoma was produced in rats by injection of 9,10-dimethyl-1,2-benzanthracene into their knee joints. The original tumors consisted mainly of fibroblast-like cells and histiocyte-like cells, often intermixed with bizarre giant cells, and they frequently showed the storiform-pleomorphic pattern. By immunohistochemistry, anti-rat macrophage monoclonal antibodies, TRPM-3, RM-1, and Ki-M2R, and anti-rat leukocyte common antigen reacted to the histiocyte-like cells but not to the fibroblast-like cells. By the single cell cloning method, we established six tumor cell lines, none of which reacted with the anti-rat macrophage monoclonal antibodies, possessed any Fc receptors, or conducted immune phagocytosis and Latex particle phagocytosis. The ultrastructure of the cloned tumor cells resembled that of long-term cultured dermal fibroblasts. Collagen production by the tumor cells was demonstrated immunohistochemically with a monoclonal antibody for type I collagen. Inoculation of the cloned tumor cells into rats produced tumors with the histology of malignant fibrous histiocytoma and induced prominent macrophage infiltration. In the rat tumors produced by the inoculation of [3H]thymidine labeled cells, no reactivity of tumor cells with the anti-rat macrophage monoclonal antibodies was observed. Transplantation of the cultured rat tumor cells into nude mice produced tumors similar in histology to the original rat malignant fibrous histiocytoma. Tumor cells in nude mice induced marked macrophage infiltration as detected by immunohistochemistry with the anti-mouse macrophage monoclonal antibody F4/80. No differentiation of tumor cells into macrophages was detected, since no cells were stained with biotinylated anti-rat macrophage monoclonal antibody TRPM-3. By the flash labeling method with [3H]thymidine, infiltrating macrophages in the nude mouse tumors were proved to derive from the bone marrow of the host animals. These results indicate a possible experimental reproduction of malignant fibrous histiocytoma by proliferation of malignant fibroblasts or their related cells in combination with macrophage infiltration.     

h-Caldesmon as a specific marker for smooth muscle tumors. Comparison with other smooth muscle markers in bone tumors

Caldesmon is a protein widely distributed in smooth and non-smooth muscle cells and is thought to regulate cellular contraction. Its isoform, high-molecular-weight caldesmon (h-CD), was demonstrated to be specific for smooth muscle cells and smooth muscle tumors of the soft tissue and to never be expressed in myofibroblasts. We performed an immunohistochemical study to examine h-CD expression in the following bone tumors: conventional and non-conventional osteosarcoma, 13; malignant fibrous histiocytoma of bone, 5; giant cell tumors of bone, 5; chondroblastoma, 3; metastatic leiomyosarcoma, 2; and rhabdomyosarcoma, 1. Frequent immunoreactivity for muscle actin (alpha-smooth muscle actin or muscle-specific actin) was seen in 11 of 13 osteosarcomas and all other tumors, whereas h-CD was expressed intensely only in 2 leiomyosarcomas. h-CD is considered a specific and useful marker to distinguish smooth muscle tumor from bone tumors with myoid differentiation.     

Matrix Vesicles in Bone Tumors

Bone tumors were categorized into alkaline phosphatase (ALPase)-positive (2 ossifying fibromas, 1 benign osteoblastoma and 16 osteosarcomas) and negative (2 chondromas, 2 chondrosarcomas, 3 non ossifying fibromas, 2 malignant fibrous histiocytomas and 6 giant cell tumors of bone) groups. Production and distribution of matrix vesicles (MVs) in the tumor tissues were examined to clarify their role in neoplastic bone formation. Four distinct types of MV were isolated primarily in ALPase-positive bone tumors: empty, amorphous, crystalline and ruptured MVs. They were formed by budding off from the cytoplasmic projections of the osteoblastic tumor cells. The significance of differences in the production rate of MVs between ALPase positive and negative bone tumors was investigated in view of the predominantly high production of MVs in ALPase-positive bone tumors. Many more mature MVs (crystalline and ruptured) were observed in the osteoblastic lesions of osteosarcoma than in the fibroblastic and MFH-like lesions, suggesting an intimate relationship with maturation and differentiation of the osteoblastic tumor cells. The above findings indicate that production of MVs is one of the diagnostic parameters for osteoblast- derived bone tumors, as well as ALPase activity, and that vesicle-induced mineralization is a major mineralization mechanism in neoplastic bone formation. Acta Pathol Jpn 41: 610-617, 1991.     

Malignant fibrous histiocytoma arising in a recurrent chordoma

Summary We present the case of a sacrococcygeal chordoma which recurred 15 years after the radical removal as a soft tissue tumor in the gluteal musculature. This tumor consisted of two parts: a chordoma without symptoms of aggressive cellular proliferation and a malignant fibrous histiocytoma. During the following 4 years several local recurrences of the malignant fibrous histiocytoma occurred in the gluteal musculature. The patient finally died of lung metastases. No chordoma tumor tissue was found in the lungs, in the gluteal musculature or in the sacrococcygeal bone area. Histology including electron microscopy revealed no proof of a transition of chordoma into malignant fibrous histiocytoma. It must be assumed that the secondary soft tissue tumor originated from residual chordoma cells which were implanted during the operation of the primary tumor. It remains unclear whether the malignant fibrous histiocytoma arose from mesenchymal stromal cells within the chordoma or directly from primitive neuroectodermal chorda cells which possess the ability to differentiate into a variety of cell types including mesenchymal cells.     

Malignant soft tissue tumors (malignant fibrous histiocytoma, pleomorphic liposarcoma, and pleomorphic rhabdomyosarcoma): an electron microscopic study.

A comparative ultrastructural analysis of malignant soft tissue tumors (malignant fibrous histiocytoma, pleomorphic liposarcoma, and pleomorphic rhabdomyosarcoma) revealed similar ultrastructural features in this group of tumors. However, by electron microscopy these tumors can be differentiated on the basis of cytoplasmic and extracytoplasmic features (myosin filaments, lipid droplets, and perinuclear intermediate filaments, for example). This is even true of less well differentiated tumors and tumor cells. These findings support and amplify the concept of a common histogenesis for tumors of mesenchymal origin. Paradoxical features observed by light microscopy warrant further study by electron microscopy if the correct diagnosis is to be made in atypical cases, such as apparent malignant fibrous histiocytoma with cross striations.     

Malignant fibrous histiocytoma with special reference to its differential diagnosis

The histological diagnosis of malignant fibrous histiocytoma (MFH) seems to have become recently fashionable among pathologists, although its histogenesis and diagnostic criteria are not entirely settled as yet. For practical purposes the differential diagnosis with other easily mistakable mesenchymal tumors should be strictly made with great caution, because of variable histological features of this tumor. The authors attempted to elucidate the differential points from other tumors in a review of 189 cases of malignant soft tissue tumors. Some cases of carcinoma mimicking MFH were also reviewed. No single criterion for making the histological diagnosis of MFH was obtained. Its histological features and differential points from pleomorphic rhabdomyosarcoma and fibrosarcoma were tabulated. The recognition of a true tumor osteoid was emphasized as a single differential point between osteosarcoma and MFH often with fibrous areas mimicking osteoid. Renal cell carcinoma metastasizing to bone, which was misinterpreted as MFH on biopsy tissue, was also described and its differential point was stated.     

The rise and fall of malignant fibrous histiocytoma

The term malignant fibrous histiocytoma was coined by Stout and associates in the 1960s to encompass pleomorphic soft tissue sarcomas presumably derived from histiocytes that are capable of fibroblastic transformation. The concept was reaffirmed in the following 2 decades and malignant fibrous histiocytoma thus was regarded as the most common soft tissue tumor in older adults. However, recent more critical clinicopathologic, ultrastructural, and immunohistochemical studies have shown that malignant fibrous histiocytomas are not derived from histiocytic "facultative fibroblasts" and many neoplasms so diagnosed actually are pleomorphic subtypes of other sarcomas. Meticulous electron microscopic and immunohistochemical investigations also found that the more common storiform-pleomorphic, myxoid, and perhaps the giant cell subtypes are composed of variable mixtures of fibroblasts and phenotypically modulated fibroblastic cells, notably myofibroblasts and histiofibroblasts. On the basis of these findings, we propose a new classification for the above subtypes of so-called malignant fibrous histiocytoma, the majority of which are variants of pleomorphic fibrosarcoma.     

Malignant fibrous histiocytoma of bone.

Existence of an entity called malignant fibrous histiocytoma of bone was emphasized, based on two of our own cases experienced recently and on previous reports related to this tumor. Histologically the tumor resembles markedly the malignant fibrous histiocytoma originating in the soft part. In addition, an attempt was made to clarify its biological behavior, histological subclassification and criteria to be malignant and differential diagnoses from several other bone diseases which sometimes mimic this malignant bone tumor.     

The Rise and Fall of Malignant Fibrous Histiocytoma

The term malignant fibrous histiocytoma was coined by Stout and associates in the 1960s to encompass pleomorphic soft tissue sarcomas presumably derived from histiocytes that are capable of fibroblastic transformation. The concept was reaffirmed in the following 2 decades and malignant fibrous histiocytoma thus was regarded as the most common soft tissue tumor in older adults. However, recent more critical clinicopathologic, ultrastructural, and immunohistochemical studies have shown that malignant fibrous histiocytomas are not derived from histiocytic “facultative fibroblasts” and many neoplasms so diagnosed actually are pleomorphic subtypes of other sarcomas. Meticulous electron microscopic and immunohistochemical investigations also found that the more common storiform–pleomorphic, myxoid, and perhaps the giant cell subtypes are composed of variable mixtures of fibroblasts and phenotypically modulated fibroblastic cells, notably myofibroblasts and histiofibroblasts. On the basis of these findings, we propose a new classification for the above subtypes of so-called malignant fibrous histiocytoma, the majority of which are variants of pleomorphic fibrosarcoma.     

Soft tissue giant cell tumor of low malignant potential: a proposal for the reclassification of malignant giant cell tumor of soft parts.

Although "giant cell tumor of soft parts" has traditionally been considered a single entity as reflected in the original term "malignant giant cell tumor of soft parts (MGCT)" and later by the term "malignant fibrous histiocytoma, giant cell type" the degree of atypia and mitotic activity varies in this group, suggesting biologic heterogeneity. The clinicopathologic features of 31 tumors meeting the traditional criteria of MGCT but having only mild to moderate nuclear atypia are presented. Patients with these tumors (19 females; 12 males) ranged in age from 14 to 84 years (mean, 40 years) and presented with masses of involving either superficial (n = 16) or deep (n = 13) soft tissue. Most occurred on the arm or hand (n = 16) and ranged in size from 0.7 to 6.5 cm (mean, 2.1 cm). The tumors consisted of sheets and nodules of rounded mononuclear cells that blended with spindled cells and benign osteoclastic giant cells. Pleomorphic giant cells were absent. Osteoid was noted in 10 cases, but features typically associated with tenosynovial giant cell tumors (such as dense stromal hyaline, siderophages, and xanthoma cells) were nearly always absent. Mitotic figures ranged from 1-10/10 HPF (mean, 2-3/10 high-powered field), and angiolymphatic invasion was present in 10 cases. Necrosis was absent, however. The mononuclear cells expressed CD68, tartrate-resistant acid phosphatase, and smooth muscle actin, but lacked CD45, S100 protein, desmin, and lysozyme, an immunophenotypic profile identical to that of giant cell tumor of bone. Follow-up information in 19 patients (mean, 3 yrs; median, 1-7 yrs) indicated recurrences in four patients, but none developed metastasis. This behavior contrasts significantly with the high-grade behavior traditionally associated with MGCT of soft parts. These giant cell tumors can be consistently recognized by the lack of cytologic atypia even in the face of mitotic activity and vascular invasion. Although their long term metastatic risk is not fully defined, we propose they be termed "giant cell tumors of low malignant potential" and regarded as the soft tissue analogue of giant cell tumor of bone. The term "malignant giant cell tumor of soft parts" or giant cell malignant fibrous histiocytoma should be restricted to histologically high-grade lesions.     

The Rise and Fall of Malignant Fibrous Histiocytoma

The term malignant fibrous histiocytoma was coined by Stout and associates in the 1960s to encompass pleomorphic soft tissue sarcomas presumably derived from histiocytes that are capable of fibroblastic transformation. The concept was reaffirmed in the following 2 decades and malignant fibrous histiocytoma thus was regarded as the most common soft tissue tumor in older adults. However, recent more critical clinicopathologic, ultrastructural, and immunohistochemical studies have shown that malignant fibrous histiocytomas are not derived from histiocytic “facultative fibroblasts” and many neoplasms so diagnosed actually are pleomorphic subtypes of other sarcomas. Meticulous electron microscopic and immunohistochemical investigations also found that the more common storiform-pleomorphic, myxoid, and perhaps the giant cell subtypes are composed of variable mixtures of fibroblasts and phenotypically modulated fibroblastic cells, notably myofibroblasts and histiofibroblasts. On the basis of these findings, we propose a new classification for the above subtypes of so-called malignant fibrous histiocytoma, the majority of which are variants of pleomorphic fibrosarcoma.     

Primary malignant giant cell tumor of bone: "dedifferentiated" giant cell tumor

Well documented examples of primary malignant giant cell tumor of bone (giant cell tumor and concurrent sarcoma arising de novo) are exceedingly rare in the literature. We report a case arising in the left ischium of a 44-yr-old man. He had no previous history of radiation therapy or multiple resections. Histologically, the tumor was a typical giant cell tumor of bone juxtaposed to a malignant fibrous histiocytoma (MFH). The juxtaposition of a high grade sarcoma (MFH) and a locally aggressive nonmalignant neoplasm such as giant cell tumor is analogous to several other tumors of bone and soft tissue in which a low grade malignant or locally aggressive tumor can be associated with MFH or fibrosarcoma de novo, namely chondrosarcoma, chordoma, liposarcoma, and well differentiated intraosseous and parosteal osteosarcoma. The presence of a high grade malignant component in each of the aforementioned neoplasms generally portends a more ominous prognosis, although this is not invariably true. Recognition of the phenomenon of "dedifferentiation" (or tumor progression) in some bone tumors and sarcomas is important to ensure appropriate treatment. Distinction from secondary malignant giant cell tumors which are usually radiation induced is also important, since the latter have a much worse prognosis than those with dedifferentiation occurring de novo.