Detection of mRNAs for urokinase-type plasminogen activator, its receptor, and type 1 inhibitor in giant cell tumors of bone with in situ hybridization.

Although giant cell tumor of bone (GCT) is generally considered to be an uncommon benign neoplasm, it can pursue an aggressive course with local recurrence and metastasis. Attempts to predict the biological behavior of GCT with histopathological parameters, however, have not been successful. The urokinase-type plasminogen activation system has been implicated in tumor invasion and metastasis and abnormalities of the components of this system have been found in several malignancies. In this study we postulated that the urokinase-type plasminogen activation system associated with bone destruction and local invasion is present in GCT. We therefore evaluated the mRNA levels for urokinase-type plasminogen activator (u-PA), urokinase-type plasminogen activator receptor (u-PAR), and plasminogen activator inhibitor type 1 (PAI-1) by using Northern blot analysis and in situ hybridization in four cases of GCT and spindle-shaped mononuclear cells at the 35th passage from a GCT. Our results showed that giant cell tumors of bone contained variable levels of u-PA, u-PAR, and PAI-1 mRNA, respectively, 2.3, 1.4, and 3.2 kb in size. In situ hybridization showed that u-PA, u-PAR, and PAI-1 mRNA were expressed in both the mononuclear cells and the osteoclast-like giant cells; the signal for u-PA mRNA in the spindle-shaped mononuclear cells was more intense than that in the osteoclast-like multinuclear giant cells. Some spherical mononuclear cells (macrophage-like cells) expressed high levels of PAI-1 mRNA in comparison with the spindle-shaped mononuclear cells. In addition, the 35th passaged spindle-shaped mononuclear cells were used to study the gene expression of u-PA during cell proliferation. The results showed that the level of u-PA mRNA increases after adding 10% fetal calf serum to quiescent cells. The induction was maximal at 16 hours and remained high during 48 hours of treatment. In conclusion, even though osteoclast-like cells are ultimately responsible for the bone resorption of GCT, the mononuclear neoplastic cells of GCT may also be involved in degradation of the extracellular matrix during invasive growth by facilitating the urokinase plasminogen activation system. In addition, our observation of upregulation of u-PA mRNA in spindle-shaped mononuclear cells after serum stimulation indicated that u-PA production may be linked to tumor growth.     

Hepatic giant cell carcinoma. An ultrastructural and immunohistochemical study

Hepatocellular carcinoma with osteoclast-like giant cells (hepatic giant cell carcinoma [HGCC]) is a rare entity, with only three cases reported. The tumor is histologically similar to giant cell tumor (GCT) of bone, and the origin of the multinucleated giant cells and mononuclear stromal cells has not been determined. The purpose of this report is to present a case of this rare tumor and compare its ultrastructural and immunohistochemical features with those of a conventional GCT of bone. Histologically, the HGCC consists of sheets of osteoclast-like giant cells with a background of mononuclear cells. The giant cells lack the pleomorphism seen in hepatocellular carcinomas with anaplastic giant cells. At the light microscopic level, most of this tumor was nearly identical to a GCT of bone, but several microscopic fields (less than 5% of the tumor) had the histologic appearance of a "usual" hepatocellular carcinoma. The hepatic tumor was negative for HAM 56, epithelial cytokeratins, muramidase, and alpha-1-antitrypsin, with only focal positivity for chymotrypsin in mononuclear and giant cells. The GCT was strongly positive for alpha-1-antitrypsin and chymotrypsin in both the mononuclear and giant cells and showed focal, weak staining for AE1 and AE3 in the mononuclear stromal cells. Ultrastructurally, both mononuclear and giant cells of the HGCC showed features typical of hepatocellular carcinoma. Although the patient presented in this report died, the pattern of growth was different from most hepatocellular carcinomas. The overall histologic features of this tumor are distinctive and appear to justify separating this variant from other types of hepatocellular carcinoma.     

Biologic characterization of human bone tumors. III. Giant cell tumor of bone. A combined electron microscopical, histochemical, and autoradiographical study

The cytogenesis of giant cell tumors of bone was studied in 6 cases by combined electron microscopical, histochemical and autoradiographical investigations. Electron microscopy identified two different types of mononuclear stromal cells: fibroblast-like cells with spindly shape and numerous membranes of the granular ER occur together with macrophages bearing many large lysosomes and a prominent Golgi apparatus. Enzyme histochemical results reflect the same diversity: One portion of mononuclear cells exhibits strong alpha-naphthyl acetate esterase (ANAE) activity, known as a marker for cells of the mononuclear phagocyte system, while the other, fibroblast-like cell type is ANAE negative. Tumor giant cells contain numerous membranes of granular ER, mitochondria, and a few isolated lysosomes. They lack the typical brush border of osteoclasts. Moderate to strong ANAE activity of these giant cells reflects their belonging to the mononuclear phagocyte system. Consequently, the giant cell tumor of bone consists of two different cell types, i.e. fibroblast-like cells and cells of the mononuclear phagocyte system, and so is appraised as a fibrohistiocytic tumor. A new inference from our autoradiographic findings is that tritiated thymidine is incorporated only by mononuclear cells, but not by giant cells. Electron microscopical autoradiography demonstrated that among the mononuclear cells, only fibroblasts are found to proliferate, but not macrophages. Thus, the giant cell tumor of bone is seen as a neoplasm of fibroblastic cells with a strong reactive infiltration of cells from the mononuclear phagocyte system.     

Carcinoma of the parotid gland with osteoclastlike giant cells. Immunohistochemical and ultrastructural observations

We describe an unusual type of carcinoma of the parotid gland in a 67-year-old man. Because of rapid tumor growth, radical parotidectomy was done. Light microscopic study of the tumor revealed focal gland formation with transition to anaplastic carcinoma. Among the undifferentiated mononuclear cells and bizarre large cells were scattered many osteoclastlike multinucleated giant cells. Immunohistochemical studies on paraffin sections revealed positive staining for epithelial membrane antigen in the epithelial component; however, the multinucleated giant cells were clearly negative for this antigen. Reactions for other cell constituents (carcinoembryonic antigen, alpha 1-antitrypsin, alpha-1-antichymotrypsin, Leu-M1, Leu-M3, lysozyme, and factor VIII-related antigen) were negative in both epithelial and giant cell components of the tumor. Electron microscopy revealed poorly formed cell junctions and numerous microvilli on the surface of the mononuclear tumor cells and multinucleated giant cells, features considered not of diagnostic significance. Similar to carcinomas with osteoclastlike multinucleated giant cells in other organs, this parotid gland tumor has shown clinical and morphologic evidence of aggressive growth; pulmonary metastases developed and the patient died 28 months after radical surgery.     

Giant cell tumor of bone: An immunohistochemical comparative study

Forty-seven cases of giant cell tumor (GCT) of bone were reviewed pathologically to elucidate the origin of spindle-shaped stromal cells or the hlstogenesls of mononuclear histiocytic stromal cells and osteoclast-like giant cells (OCGC). To clarify the histogenesis of OCGC, eight cases of sarcoma associated with OCGC were reviewed for a comparative study. Spindle-shaped stromal cells sometimes produced minute foci of osteoid matrix. Proliferating cell nuclear antigen (PCNA) was observed In spindle-shaped stromal cells and mononuclear histlocytic stromal cells, but not in OCGC. Matrix metalloprotelnase (MMP)-9 was expressed by mononuclear histiocytic stromal cells and OCGC, and its expression was correlated with the lung metastasis rate. In both GCT and sarcomas with OCGC, mononuclear histiocytic stromal cells and OCGC expressed CD68, parathyroid hormone-like protein (PTH-LP), MMP-1 and MMP-9. Immunoreactivity of mononuclear histiocytic stromal cells and OCGC to CD68, PTH-LP, MMP-1 and MMP-9 was similar between GCT and sarcomas with OCGC. These observations may suggest that mononuclear histiocytic stromal cells and OCGC are reactively Induced with several cytokines acting in an autocrine or paracrine fashion and that these cells are closely related with the biologic aggressiveness of GCT.     

Osteoclast-like giant cell tumor of the pancreas: an immunohistochemical and ultrastructural study

We report a rare case of osteoclast-like giant cell tumor of the pancreas in a 70-year-old Japanese woman. The tumor was composed of a proliferation of ovoid to spindle-shaped mononuclear cells admixed with osteoclast-like giant cells. The tumor cells were immunore-active for vimentin, ±₁-antitrypsin, and CD68. In ultrastructural examination, the giant cells resembled osteoclasts, and the mononuclear stromal cells had fibroblastic and histiocytic features. No elements of epithelial differentiation were found in this tumor. These findings suggest that this tumor had a derivation similar to giant cell tumor of bone.This study was presented at the 28th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Osaka, October 17–19, 1996.     

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.     

Giant cell tumors of tendon sheath: A single and multiple immunostaining analysis

Nineteen giant cell tumors of tendon sheath (GCTTS) were studied to elucidate the origin of the proliferating cells of these tumors, using single and multiple immunostaining techniques with a labeled avidin-biotin [LAB] method in paraffin-embedded tissues. Proliferating cell nuclear antigen (PCNA) and Ki-67 (MIB-1) antigen were present in mono-nuclear cells (PCNA 26%; MIB-1 4%) but were absent in giant cells. These findings indicate that mononuclear cells, but not giant cells, participate in the proliferative compartment of GClTS. A histiocytic marker, HAM56, was positive in many mononuclear cells (mean 81%), but was totally negative in osteoclastic giant cells. Another histiocytic antigen, CD68, was expressed in both mononuclear cells (mean 28%) and most of the giant cells (mean 89%). By triple immunostaining for PCNA, HAM56 and vimentin, 83% of PCNA-positive mononuclear cells co-expressed HAM56. Because of the frequent co-expression of PCNA and HAM56, the main portion of proliferating cells in GClTS may represent a mono-cyte/macrophage lineage. However, there is a small but definite mesenchymal/fibroblastic component, characterized by PCNA+vimentin+HAM56^--, relating to the proliferative compartment of GCTTS. Multiple immunostainings with MIB-1 showed similar patterns to those with PCNA. These observations indicate that the GCTTS represent bimodal proliferatbe lesions consisting of histiocytic and mesenchymal/fibroblastic elements.     

Similarities between giant cell tumor of bone, giant cell tumor of tendon sheath, and pigmented villonodular synovitis concerning ultrastructural cytochemical features of multinucleated giant cells and mononuclear stromal cells

The authors investigated ultrastructural cytochemical features of multinucleated and mononuclear stromal cells in giant cell tumor of bone (GCTB), giant cell tumor of tendon sheath (GCTTS), and pigmented villonodular synovitis (PVNS). Specimens of each tumor, respectively numbering 4, 4, and 3, were stained for tartrate-resistant acid phosphatase (TRAP) reactions and examined with an electron microscope. In GCTB and GCTTS, multinucleated cells, including some relatively small giant cells, showed TRAP activity and cytoplasmic features characteristic of osteoclasts, and also sometimes abundant rough endoplasmic reticulum and siderosomes. A few giant cells with macrophage-like features and slight TRAP activity were demonstrated in GCCTS and PVNS. In each tumor type, mononuclear cells showing TRAP activity shared cytoplasmic features with osteoclast-like multinucleated giant cells, while some others had macrophage-like features, and still others were poorly differentiated; a few mononuclear cells showed cell-to-cell contact. Ultrastructural similarities of TRAP-positive mononuclear cells in the three tumor types, and those between TRAP-positive multinucleated cells in GCTB and GCTTS, suggest a common cell lineage capable of multinucleated giant cell formation in the 3 tumors, despite differing histogenesis.     

Cyclin alterations in giant cell tumor of bone.

Cyclins play an important role in regulating the passage of dividing cells through critical checkpoints in the cell cycle. Because alterations of several cyclins, especially cyclin D1, have been implicated in the development of many human neoplasms, we examined 32 cases of giant cell tumor of long bones for cyclin D1 gene amplification and protein overexpression using differential polymerase chain reaction and immunohistochemistry, respectively. In addition, the expression of cyclin D3, cyclin B1, and the proliferation-associated antigen Ki-67 (MIB-1) was assessed immunohistochemically. Low-level cyclin D1 gene amplification was detected in 61% of giant cell tumor cases. All tumors showed cyclin D1, cyclin D3, cyclin B1, and Ki-67 (MIB-1) staining; however, the distribution was very characteristic. Cyclin D1 protein expression was seen predominantly in the nuclei of the giant cells, with occasional mononuclear cells staining. There was no correlation between cyclin D1 gene amplification and protein overexpression. Cyclin D3 staining showed a similar distribution, with 88% of cases showing protein overexpression. Cyclin D1 and/or D3 staining in the giant cells was never associated with staining for either cyclin B1 or Ki-67 (MIB-1), as the expression of the latter two proteins was restricted to the mononuclear cells. Cyclin B1 overexpression was seen in 44% of cases. Ki-67 (MIB-1) staining was present in all cases, and between 10 to 50% of the mononuclear cells were positive. These results suggest that alterations in cyclin D1 and/or D3 might play a role in the pathogenesis of giant cell tumor of bone.     

Origin of giant cells in osteoclast-like giant cell tumors of the pancreas

To clarify the origin of giant cells in osteoclast-like giant cell tumors (OGCTs) of the pancreas, we performed microscopical, immunohistochemical, and K-ras gene mutation analyses with a microdissection approach in 3 cases, featuring 4 cellular components (osteoclast-like giant cells [OGCs], pleomorphic large cells [PLCs], mononuclear cells, and ductal carcinoma cells). Two cases had abundant OGCs, and 1 case contained large number of both OGCs and PLCs. In each, none of the microdissected OGCs contained any K-ras gene mutation while they were positive for a histiocytic marker (CD-68). In contrast, PLCs, when present, frequently harbored K-ras gene mutations and were negative for CD-68. In all cases, mononuclear cells, a mixture of histiocyte-like and atypical, from microscopic and immunohistochemical viewpoints, also frequently showed K-ras alteration. Histiocyte-like mononuclear cell was equipped with a regular and oval nucleus similar to those in OGCs and was positive for CD-68. Atypical mononuclear cell showed an irregular, pleomorphic, or sometimes bizarre nucleus similar to those in PLCs and was negative for CD-68. All of the K-ras gene mutations found in PLCs and mononuclear cells were the same as in the ductal carcinoma cells within the same tumor. Thus, OGCs differ in origin from ductal cells and are strongly suggested to be nonneoplastic and of mesenchymal origin, whereas PLCs, which harbor K-ras gene mutations, are neoplastic and presumably derived from ductal carcinoma cells. Moreover, mononuclear cells may be classified into 2 types, histiocyte-like and atypical.     

Large mononuclear cells in seminoma--an immunohistochemical analysis of 21 cases

Twenty-one cases of seminoma (including testicular seminoma, ovarian dysgerminoma and extragonadal germinoma) were reviewed for the cell types responsible for the production of alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG). Histologically the cases included seventeen classical seminomas and 4 anaplastic seminomas. The latter had some mononuclear and multinuclear giant cells. All 4 patients with anaplastic seminoma had elevated levels of serum AFP, and each of these cases contained AFP producing tumor cells identified by immunoperoxidase staining. All seminomas of patients with elevated serum levels of HCG were of the classical type but HCG producing tumor cells could not be identified by immunoperoxidase staining. Immunoreactivity to anti-AFP was found in some large mononuclear cells and anaplastic cells. To explain these results, we propose that the large mononuclear cell is a multipotential cell capable of differentiating into a germ cell, yolk sac and embryo, and that the anaplastic seminoma cells might represent a stage on the continuum of cellular differentiation from the large mononuclear cells to germ cells. The multinuclear giant cell does not appear to be essential for the production of either AFP or HCG in seminoma.     

Immunohistochemical study of mononuclear phagocyte antigens in giant cell tumor of bone.

The cytogenesis of giant cell tumor of bone (GCT) was assessed by immunohistochemical methods. Three GCT were analyzed by a sensitive immunoalkaline phosphatase technique with a panel of monoclonal antibodies, including eight reacting with separate antigens previously found to be present on mononuclear phagocytes (MPs) and one specific for the endothelial marker, coagulation Factor 8. Among the MP-associated antigens evaluated were leukocyte common antigen (LCA), HLA-DR, C3b receptor, and C3bi receptor. Also incorporated in the panel were antibodies to MP-associated antigens with well-characterized tissue distribution but of currently unknown function. Constituent cells of the tumors varied in their reactions with the antibodies of the panel. Although mononuclear cells in tumor stroma were labeled with all of the antibodies against the MP markers, giant cells reacted strongly only with antibodies to LCA and the MP-associated antigen recognized by the antibody EBM11. Giant cells were weakly and focally labeled with antibodies (KB90 and UCHM1) against two additional MP-associated determinants and were unreactive with the remaining antibodies in the panel. Spindled stromal cells, which appeared to produce collagen, were not labeled with any of the antibodies in the panel. Only endothelial cells reacted with antibody to Factor 8. The results of this study suggest that giant cells of GCT are derived from stromal cells of mononuclear phagocyte lineage, and that the stromal precurser cells lose some, but not all, MP-associated antigens as they mature into giant cells.     

Giant cell tumor of soft tissue arising in breast

Primary giant cell tumor of soft tissue (GCT-ST) arising in breast is exceedingly rare. We report a case of a 60-year-old woman with a primary breast giant cell tumor that appeared histologically identical to giant cell tumor of bone and had a clinically malignant course. The patient presented with a cystic mass of the breast, suspected on imaging to be an organizing hematoma, possibly related to previous injury. Histopathological evaluation revealed a neoplasm composed of mononuclear cells admixed with osteoclast-like giant cells resembling giant cell tumor of bone. Immunohistochemical staining was positive for CD68, smooth muscle actin, and vimentin, but was negative for a panel of epithelial and additional muscle markers. These features were most consistent with GCT-ST, an uncommon neoplasm of low malignant potential. Despite aggressive surgical treatment achieving clear surgical margins, the patient expired with pulmonary metastases within a year of her initial presentation. This case demonstrates the difficulty of predicting clinical behavior of GCT-ST of breast on the basis of histological features and depth of tumor alone. To our knowledge, this is the first case report of a GCT-ST arising in the breast associated with a fatal outcome. The distinction of this entity from other more common primary breast tumors with giant cell morphology is also emphasized.     

解整合素-金属蛋白酶1 2基因在骨巨细胞瘤组织中的表达及意义

目的 检测解整合素-金属蛋白酶12（ADAM12）基因在骨巨细胞瘤组织中的表达和定位,探讨其对骨巨细胞瘤中多核巨细胞形成的作用。方法 用逆转录-聚合酶链反应（RT-PCR）检测18例、用RNA原位杂交检测12例骨巨细胞瘤患者的瘤组织、6倍体外培养骨巨细胞瘤瘤细胞、2例胚胎横纹肌和5例成人横纹肌组织的ADAM12mRNA。结果 RT-PCR显示,18例骨巨细胞瘤组织中,12例（67%）有ADAM12mRNA表达;RNA原位杂交则显示12例骨巨细胞瘤组织全部呈ADAM12阳性反应,并且位于几乎所有的多核巨细胞和单核基质细胞质中。随着骨巨细胞瘤培养细胞传代次数的增多和多核巨细胞的消失,ADAM12mRNA的表达也逐渐消失。结论 骨巨细胞瘤中的多核巨细胞可能是由单核基质细胞融合而成,ADAM12基因参与这一融合过程。     

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.     

Histogenesis of giant cell tumors

The giant cell tumor of bone (GCT) is a local osteolytic tumor with variable degrees of aggressiveness. In rare cases pulmonary metastases can be observed. The lesion most frequently occurs in the epiphysis of long tubular bones of the knee region, predominantly affecting young adults after closure of the growth plate. The characteristic histological appearance of GCT displays a high number of osteoclast-like multinucleated giant cells, which resulted in the classification "osteoclastoma" or "giant cell tumor". Apart from the multinucleated giant cells, there are two mononuclear cell types in the GCT. The first one has a round morphology and resembles a monocyte. The second cell type is the spindle-shaped, fibroblast-like stromal cell. Cell culture experiments with GCT cells revealed the stromal cell to be the proliferating component of the GCT. The other two cell types, the monocyte and the multinucleated giant cell, were lost after a few cell culture passages. Furthermore, latest results from GCT reveal that the stromal cells secrete a variety of cytokines and differentiation factors, including MCP1, ODF and M-CSF. These molecules are monocyte chemoattractants and are essential for osteoclast differentiation, suggesting that the stromal cell stimulates blood monocyte immigration into tumor tissue and enhances their fusion into osteoclast-like, multinucleated giant cells. The multinucleated giant cell itself demonstrates properties of a normal osteoclast that is able to resorb bone leading to extended osteolysis. This new model of GCT genesis supports the hypothesis that the stromal cell is the neoplastic component whilst the monocytes and the multinucleated giant cells are just a reactive component of this tumor. Taking this into consideration, the nomenclature of the "giant cell tumor" needs to be reconsidered.     

Endoscopic ultrasound-guided fine-needle aspiration of undifferentiated carcinoma with osteoclast-like giant cells of the pancreas: a report of 2 cases with literature review

Undifferentiated carcinoma with osteoclast-like giant cells of the pancreas is rare. Histologically it mimics the giant cell tumor of the bone and may be associated with a ductal adenocarcinoma. We recently encountered two such cases, both of which were biopsied by EUS-guided FNA. Abundant multinucleated osteoclast-like giant cells and many uniform mononuclear cells were present in case 1 so that the diagnosis was made. In case 2, many mononuclear tumor cells with vacuolated and basophilic cytoplasm were present, and rare osteoclast-like giant cells were seen. A diagnosis of adenocarcinoma was made. In both cases, no conspicuous nuclear pleomorphism was noted in the mononuclear cells or the multinucleated giant cells. The histology of case 2 revealed a pure undifferentiated carcinoma with osteoclast-like giant cells. In addition, a liver biopsy revealed globular amyloidosis. To our knowledge, this is the first report of pancreatic undifferentiated carcinoma with osteoclast-like giant cells sampled by EUS-guided FNA and the first case of hepatic globular amyloidosis associated with this tumor.     

Combined hepatocellular carcinoma and osteoclast-like giant cell tumor of the liver: Possible clue to histogenesis

Hepatic giant cell tumor is extremely rare, and only five cases have been reported of overt hepatocellular carcinoma, thus its histogenesis is controversial. Herein is reported a case of simultaneous hepatocellular carcinoma and osteoclast-like giant cell tumor in a single tumor. A liver tumor was found in a 74-year-old woman. Histologically the tumor consisted of two distinct components: mononuclear and multinuclear giant cells with osteoclastic giant cells, and a conventional hepatocellular carcinoma. The boundary between the two components showed transitional features. Immunohistochemistry showed that the osteoclast-like giant cells were CD68 and vimentin positive, but cytokeratin and AFP negative, while spindle-shaped cells were positive only for vimentin. In a portion of the hepatocellular carcinoma the cells were cytokeratin-8 and AFP positive. Ki-67 positivity was 10% for the hepatocellular carcinoma, 60% for the spindle-shaped cells, and 0% for the giant cells. It is possible that the tumor might have had a hepatocellular carcinoma origin, given the more highly proliferative sarcomatous changes and reactive osteoclast-like cells. This case provides a clue to the histogenesis of hepatic giant cell tumors.