Osteoclasts are present in the giant cell variant of malignant fibrous histiocytoma

Cellular mechanisms of osteoclast formation and lacunar resorption in giant cell granuloma of the jaw

BACKGROUND

Giant cell granuloma (GCG) is an osteolytic tumour of the jaw which is characterised by the presence of both mononuclear and multinucleated (osteoclast-like) giant cell components. The nature of these component cells and the pathogenesis of the extensive osteolysis associated with this lesion is uncertain.

METHODS

Using cell culture techniques and immunohistochemistry, we defined the phenotypic characteristics of the mononuclear and multinucleated cells present in four cases of GCG of the jaw. We also analysed the cellular and humoral factors associated with osteoclast formation and osteolysis in these tumours and determined whether GCG stromal cells are capable of supporting osteoclast formation.

RESULTS

GCG-derived giant cells expressed the phenotypic characteristics of osteoclasts (TRAP+, VNR+, and calcitonin responsive) and were capable of lacunar resorption. In addition to macrophages, the mononuclear cell population contained numerous spindle-shaped stromal cells which proliferated in culture and expressed RANKL; these GCG-stromal cells were capable of supporting human osteoclast formation from circulating monocyte precursors.

CONCLUSION

Our findings indicate that the giant cells in GCG of the jaw are osteoclast-like and formed from monocyte/macrophage precursors which differentiate into osteoclasts under the influence of RANKL-expressing mononuclear stromal cells found in this lesion.

Phenotypic characterization of mononuclear and multinucleated cells of giant cell reparative granuloma of small bones

Four cases of giant cell reparative granuloma (GCRG) of small bones were analysed in order to determine the pathogenesis of the lesion and the nature of the component mononuclear and multinucleated cells. In cell cultures, giant cells formed a non-proliferating homogeneous population which expressed features characteristic of the osteoclast phenotype, including leucocyte common antigen, CD68, vitronectin receptor, and tartrate-resistant acid phosphatase. The giant cells were capable of lacunar resorption and their activity was inhibited by calcitonin. In addition to numerous macrophage-like cells, some of which expressed osteoclast phenotypic characteristics, there were also mononuclear stromal cells which proliferated in culture and were alkaline phosphatase-positive; these cells expressed receptor activator of NF-kappaB ligand (RANKL) and were capable of supporting human osteoclast formation from circulating precursors in vitro. These findings suggest that the osteoclast-like giant cells in GCRG of small bones are formed from monocyte/macrophage-like osteoclast precursors which differentiate into osteoclasts under the influence of mononuclear osteoblast-like stromal cells.

Primary giant cell tumor of soft tissue

BACKGROUND

Primary giant cell tumor of soft tissue, also known as soft tissue giant cell tumor of low malignant potential, is a rare soft tissue tumor located in both superficial and deep soft tissue. Histologically, these lesions bear a close resemblance to their bony counterparts, giant cell tumor of bone, with round to spindle-shaped cells intimately admixed with uniformly scattered osteoclast-like multinucleated giant cells. In 1989 in the dermatology literature, two malignant giant cell tumors of soft parts were described that filled the dermis and extended into the subcutaneous tissue.

METHODS

The authors report the rare occurrence of a giant cell tumor of soft tissue occurring primarily in the dermis that lacks overtly malignant features and clinically was thought to be an epidermal inclusion cyst.

RESULTS

Light microscopy revealed a non-encapsulated cellular dermal tumor containing numerous osteoclast-like giant cells. Cytologic atypia was minimal and the mitotic count averaged 2-3/10 HPF. The histologic differential diagnosis is also discussed.

CONCLUSION

Giant cell tumor of soft tissue is a rare neoplasm of the skin, however, recognition of this tumor is important due to its behavior as a low-grade malignancy.

Generation of human osteoclasts in stromal cell-free and stromal cell-rich cultures: differences in osteoclast CD11c/CD18 integrin expression

Osteoclasts form in the presence of macrophage colony-stimulating factor (M-CSF) and receptor activator of Nfkappab ligand (RANKL), a membrane-bound differentiation factor that is now available as a soluble recombinant molecule. Acquisition of the osteoclast phenotype [the alphavbeta3 subunit of the vitronectin receptor (VNR)-, calcitonin receptor (CTR)- and F-actin ring-positive cells] is associated with loss of monocyte/macrophage-associated integrins, specifically CD11b, CD11c and CD18. We hypothesized that differences in the osteoclast integrin adhesion molecule profile may exist in osteoclasts generated in stromal cell-rich and in stromal-free conditions. Unlike osteoclasts generated in vivo, F-actin ring-positive (resorbing) osteoclasts formed in soluble RANKL in vitro, in the absence of stromal cells, and co-expressed CD11c and CD18. However, when osteoclasts were generated from peripheral blood mononuclear cells (PBMNCs) in co-cultures with the murine bone marrow stromal cell line 218 (which does not produce membrane-bound RANKL) in the presence of soluble RANKL, CD11c and CD18 were not expressed by osteoclasts. These findings indicate that the persistent expression of CD11c and CD18 is not accounted for by RANKL being presented in a soluble form and that membrane-bound RANKL is not required for the normal integrin expression in resorbing osteoclasts. This study demonstrates that potentially misleading information may arise by using data obtained from osteoclasts generated in the absence of stromal cells as they do not completely reflect the situation in vivo.

Leiomyosarcoma of the heart and its pulmonary metastasis, both with prominent osteoclast-like multinucleated giant cells expressing tartrate-resistant acid phosphatase activity

An autopsy case of cardiac leiomyosarcoma and its pulmonary metastasis, both with osteoclast-like multinucleated giant cells (OMGC) mimicking the so-called giant cell variant of malignant fibrous histiocytoma (MFH), is reported. The patient, a 70-year-old male, was admitted for sudden dyspnea. Extensive work-up established only a left atrial tumor mass. Three months after admission, the patient developed multiple intracranial and pulmonary metastases, followed by a worsening clinical course characterized by semicoma and dyspnea, and subsequently died 6 months after the onset of his symptoms. At subsequent autopsy, the left atrial polypoid tumor was found to have invaded destructively to the left half of the cardiac wall. Histology of the cardiac tumor revealed a bimorphic sarcoma in which a poorly differentiated leiomyosarcoma comfirmed by histologic and immunohistochemical findings was juxtaposed to a small nodule with features closely mimicking giant cell MFH. The pulmonary metastatic nodules exhibited features that were entirely indistinguishable from giant cell MFH except for the fact that a minority of polymorphic cells manifested myogenic differentiation. We believe that such a MFH-like pattern represents a pleomorphic form of leiomyosarcoma rather than a dedifferentiated one. The OMGC within the MFH-like component coexpressed CD68 and tartrate-resistant acid phosphatase activity.

Study of the cell biology and biochemistry of cherubism

AIMS

To establish whether the multinucleate cells in lesions of patients with cherubism are also osteoclasts and if this is the case whether they were responsive to calcitonin; to carry out cytogenetic studies on two members of the same family affected by cherubism in an attempt to identify any major chromosomal defects; and to perform an in-depth modern biochemical study of four children in the same family.

SUBJECTS AND METHODS

Four related children with cherubism were studied. Tissue taken from one of the children at elective decompression of an optic nerve was submitted to in vitro bone resorption studies. Cytogenetic studies were done on two of the children and biochemical studies on all four.

RESULTS

The multinucleate cells in the cherubic lesions were shown to be osteoclasts since they synthesised tartrate resistant acid phosphatase, expressed the vitronectin receptor, and resorbed bone. Bone resorption by the cultured multinucleate cells was significantly inhibited by calcitonin. High resolution cytogenetic studies failed to detect any chromosomal abnormalities in two children with cherubism. The biochemistry profile of all four children with cherubism showed that serum calcium, parathyroid hormone, parathyroid related hormone, calcitonin, and alkaline phosphatase were within normal levels. Urine analysis of pyridinium and deoxypyridinium cross links, hydroxyproline, and calcium in relation to urine creatinine were measured to assess bone resorption in these children, and the values were at the upper end of the normal range in all four.

CONCLUSIONS

Further studies are required to determine whether calcitonin treatment will control this grossly deforming disease until the time when the physiological changes that occur at puberty rectify the pathology. It is not recommended that biochemical markers of bone resorption are used in isolation to monitor the activity of cherubism in individuals because the results are based on a small number of children and because of reports of marked interindividual variation in the levels of these markers, particularly in children.

Primary lung tumors infiltrated by osteoclast-like giant cells

Six primary lung tumors with numerous multinucleated osteoclast-like giant cells (OLGCs) and no osteogenic component were evaluated histologically and immunohistochemically to examine pulmonary lesions inciting an OLGC response. The patients comprised four women and two men ranging in age from 61 to 80 years (average age, 69 years). The tumors consisted of one adenocarcinoma, two sarcomatoid carcinomas, and three giant cell variants of malignant fibrous histiocytoma. One tumor was endobronchial in location, while five were situated peripherally. Tumor diameter spanned from 1 to 6.5 cm (average, 2.7 cm). In addition to the giant cells, common characteristics included the malignant nature of the neoplasms and, in five of six cases, histologically malignant mesenchyme. This array of cases exemplifies the variability of lung lesions which may elicit an OLGC inflammatory response resulting in areas resembling the giant cell variant of malignant fibrous histiocytoma. The results of this study suggest that OLGCs occur preferentially in malignant rather than benign nonosteogenic lung tumors and that sarcomatoid regions of malignant tumors are more likely to be infiltrated by OLGCs than epithelial regions.

Bone resorption by macrophage polykaryons of a pilar tumor of scalp

The nature of keratin-associated giant cells of a pilar tumor of scalp (PTS) was assessed for several osteoclast-like characteristics, including antigenic phenotype, ultrastructure, calcitonin response, and bone resorbing ability. The giant cells, unlike osteoclasts, did not respond morphologically to calcitonin, had the antigenic phenotype of cells of the monocyte/macrophage lineage, and showed ultrastructural features of macrophage polykaryons. However, like osteoclasts, the giant cells were capable of bone resorption, including resorption pit formation. This indicates that the giant cells in PTS are of histiocytic and not osteoclastic differentiation. Bone resorption by tumor-associated macrophage polykaryons shows that this is not a unique defining characteristic of osteoclasts. It also suggests that such histiocytic cells may contribute to the osteolysis associated with skeletal metastases of squamous and other carcinomas.

Phenotypic characterisation of mononuclear and multinucleated cells of giant cell tumour of bone

Studies were carried out on 3 giant cell tumours of bone (GCTB) to characterise further the cells forming the distinctive mononuclear and multinucleated components. Samples of tumours were grown as explants in vitro and implanted subcutaneously in athymic mice. Cells were characterised in terms of their cell morphology and cytochemical, antigenic and functional phenotype. In culture, giant cells formed a non-proliferative, relatively homogeneous population of cells which expressed features characteristic of the osteoclast phenotype. The mononuclear cell component was heterogeneous and included macrophage-like cells, which persisted for a short time in culture, and fibroblast-like cells which proliferated. In subcutaneous implants, the fibroblast-like cells formed a tissue which included areas of bone formation associated with regions of alkaline phosphatase activity. These observations are consistent with earlier suggestions that the neoplastic component in GCTB consists of a mononuclear stromal cell which elicits a macrophage/osteoclast response.

Giant cell variant of malignant fibrous histiocytoma of the head and neck

The giant cell variant of malignant fibrous histiocytoma is a rare entity in head and neck. Only eight well documented cases of this type are reported in the English literature. These tumours affect the superficial and deep structures of the neck most often and are best treated with prompt radical surgery. The prognosis of the giant cell type of malignant fibrous histiocytoma is dependent on the location of the tumour, with superficial tumours having a much better outlook.

Histochemistry of tartrate-resistant acid phosphatase and carbonic anhydrase isoenzyme II in osteoclast-like giant cells in bone tumours

Using routinely processed, paraffin-embedded tissue specimens, osteoclast-like giant cells in giant cell tumour of bone (GCT), chondroblastoma, osteoblastoma and osteoblastic osteosarcoma were examined histochemically for osteoclast-specific enzymes tartrate-resistant acid phosphatase (TRAP) and carbonic anhydrase isoenzyme II (CA-II). Osteoclast-like giant cells and some mononuclear cells possessed TRAP activity. These were further classified with respect to CA-II immunoreactivity, i.e. cells with CA-II were seen in GCT and chondroblastoma, while those in osteoblastoma and osteoblastic osteosarcoma were negative for CA-II. All the cellular components in malignant fibrous histiocytoma and various extraosseous inflammatory lesions including malignant giant cells and macrophage polykaryons were negative for both TRAP and CA-II. These results indicate that osteoclast-like giant cells in GCT, chondroblastoma, osteoblastoma and osteoblastic osteosarcoma are all osteoclasts and generated by fusion of mononuclear cells with the same histochemical characteristics as osteoclast-like giant cells. The difference in CA-II immunoreactivity suggests the functional or maturational difference between osteoclast-like giant cells in GCT and chondroblastoma and those in osteoblastoma and osteosarcoma.

Bone resorption by macrophage polykaryons of giant cell tumour of tendon sheath

The antigenic phenotype, ultrastructure and bone resorbing ability of mononuclear and multinucleated giant cells of four giant cell tumour of tendon sheath (GCTTS) lesions was assessed. Both the giant cells and the mononuclear cells exhibited the antigenic phenotype of cells of the monocyte/macrophage lineage. The giant cells, unlike osteoclasts, did not respond morphologically to calcitonin and showed ultrastructural and immunophenotypic features of macrophage polykaryons. However, like osteoclasts, the giant cells showed direct evidence of resorption pit formation on bone slices. This indicates that the GCTTS is composed of cells of histiocytic differentiation with the giant and mononuclear cell components expressing a similar antigenic phenotype. Bone resorption by macrophage polykaryons shows that this is not a unique defining characteristic of osteoclasts. Qualitative differences in the degree and pattern of bone resorption by macrophage polykaryons distinguish it from that of osteoclasts and may underlie the clinical behaviour of osteolytic lesions.

The giant cells recruited by subcutaneous implants of mineralized bone particles and slices in rabbits are not osteoclasts

We have compared structural and functional characteristics of native osteoclasts and the multinucleated giant cells (MNGC) recruited by subcutaneous implants of mineralized bone particles and slices in normal rabbits. Weekly evaluation of the implants for 5 weeks showed distinct differences between MNGC and osteoclasts in the host with respect to morphology and the ability to stain for tartrate-resistant acid phosphatase and acid ATPase. An osteoclast-specific monoclonal antibody bound strongly to osteoclasts but not MNGC. Ground bone slices similarly implanted were surrounded by MNGC but did not show resorption pits by scanning electron microscopy. These data show that the MNGC recruited to subcutaneous implants of mineralized bone particles and slices lack the enzymatic, cell surface, and functional features of osteoclasts.

Histochemistry and biochemistry of tartrate-resistant acid phosphatase (TRAP) and tartrate-resistant acid adenosine triphosphatase (TrATPase) in bone, bone marrow and spleen: implications for osteoclast ontogeny

In order to evaluate the usefulness of a recently described acid ATPase as a marker for osteoclast differentiation, we have performed histochemical and biochemical analyses of the distribution of tartrate-resistant acid phosphatase (TRAP) and tartrate-resistant acid ATPase (TrATPase) in bone, bone marrow and spleen. Histochemical studies of bone demonstrated that multinucleated osteoclasts stained for both TRAP and TrATPase. However, staining for TRAP covered the entire cytoplasm, whereas TrATPase staining was localized primarily to cytoplasmic areas next to bone and on adjacent mineralized surfaces. Occasionally TrATPase-positive mononuclear cells were observed on excavations in the bone surface. In the spleen, mononuclear TRAP-positive cells were located in the marginal zone between the white and red pulp, whereas no staining for TrATPase was observed. Comparison of the biochemically measured TRAP and TrATPase activities showed that bone had the highest specific activity for both enzymes followed by the bone marrow and spleen. However, enzyme activity in the spleen compared to bone was about 4-fold higher for TRAP compared to TrATPase. Additional evidence for a restricted expression of TrATPase to bone relative to spleen was obtained by in vitro translation studies. These data indicate that TrATPase is a more selective marker than TRAP in histochemical and biochemical studies of osteoclast differentiation and furthermore suggest that development of TrATPase is a late acquisition in osteoclast ontogeny.