骨的恶性巨细胞瘤临床病理观察

目的 探讨骨的恶性巨细胞瘤临床病理学特征及其诊断和鉴别诊断.方法 对13例恶性巨细胞瘤的临床及病理学资料进行回顾性分析.结果 13例恶性巨细胞瘤中原发性恶性巨细胞瘤6例,发病年龄21-71岁,平均年龄39.5岁.复发后继发性恶性巨细胞瘤7例,发病年龄27-52岁,平均年龄36.7岁.6例原发性恶性巨细胞瘤除可见到骨巨细胞瘤区域外,还可见到高度恶性的梭形细胞肉瘤区域,7例继发性恶性巨细胞瘤其原发性肿瘤均为骨巨细胞瘤,而复发性肿瘤则呈恶性纤维组织细胞瘤/未分化肉瘤形态.结论 诊断恶性巨细胞瘤时需将临床、影像及病理结合,并除外其他肉瘤如富含巨细胞的骨肉瘤、富含巨细胞的恶性纤维组织细胞瘤等.     

An extremely rare case of primary malignancy in giant cell tumor of bone,arising in the right femur and harboring H3F3A mutation

We experienced a case of primary malignancy in giant cell tumor of bone (GCTB), arising in the right femur and harboring H3F3A mutation. A 27-year-old Japanese male without any prior disease history complained of pain in his right hip joint and right lower limb. Radiological images revealed an osteolytic and multicystic lesion existing mainly at the proximal epiphysis of the right femur. Preoperative clinical diagnosis was GCTB, although irregular marginal sclerosis was an atypical radiographic finding for conventional GCTBs. Biopsy sample from the lesion revealed the coexistence of typical GCTB and undifferentiated high-grade round cell sarcoma. Despite of the wide local resection of the tumor with preoperative and postoperative chemotherapy, the patient died of multiple distant metastases of the tumor 9 months after the surgery. Since heterozygous H3F3A c. 103G>T (p. Gly34Trp) mutation was detected not only in the biopsy sample from the primary site with typical GCTB and high-grade sarcoma components but also in the resected material from the metastatic site with only pure high-grade sarcoma component, the tumor was considered originally derived from conventional GCTB and acquire malignant transformation to high-grade sarcoma. Thus, this is an extremely rare case of primary malignancy in GCTB and the first case report of primary malignancy in GCTB proved the presence of H3F3A mutation even in the sarcoma component.     

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.     

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.     

伴破骨样巨细胞平滑肌肉瘤的临床病理学观察

目的 探讨伴破骨样巨细胞平滑肌肉瘤的临床病理学特点及其鉴别诊断.方法 收集7例伴大量破骨样巨细胞平滑肌肉瘤病例的临床和影像学资料,行光镜观察、免疫组织化学(EnVision法)标记和电镜观察,并复习相关文献.结果 患者均为成年人,其中女性3例,男性4例,平均年龄 63岁.肿瘤位于大腿皮下软组织2例,左背部、腹膜后、小肠、乳腺和子宫各1例.组织学上,所有病例均由形态相对一致、呈交织条束状排列的梭形瘤细胞和大量的破骨样巨细胞组成,后者多散在分布于梭形细胞之间(6例),或形成巨细胞瘤样结节(1例).免疫组织化学标记显示,梭形细胞程度不等地表达平滑肌肌动蛋白、肌特异性肌动蛋白、结蛋白和高相对分子质量钙调结合蛋白,破骨样巨细胞表达CD68.电镜观察显示梭形细胞具平滑肌分化特征,破骨样巨细胞则具组织细胞分化.随访6例患者,均在术后发生复发或转移,其中3例带瘤生存,2例死亡.结论 (1)伴大量破骨样巨细胞的平滑肌肉瘤是平滑肌肉瘤的一种少见亚型,形态上与巨细胞型恶性纤维组织细胞瘤相似,诊断时应注意加以鉴别.(2)免疫组织化学标记和电镜观察提示肿瘤内的破骨样巨细胞起源于单核细胞/组织细胞系.(3)该肿瘤的恶性程度高,预后差.

Abstract：

Objective To study the clinicopathologic features of leiomyosarcoma with prominent osteoclast-like giant cells. Methods The clinical and pathologic features of 7 cases of leiomyosarcoma with prominent osteoclast-like giant cells were analyzed. Immunohistochemical and ultrastructural studies were performed. The literature was reviewed. Results All cases occurred in adults, with a mean age of 63 years. There was no significant soft tissue of thigh (number=2), left back (number=1), retroperitoneum (number=1), small intestine (number=1), breast (number=1) and uterus (number=1). Histologic examination showed that the tumor was composed of relatively uniform spindly cells arranged in interlacing fascicles. The hallmark was the presence of prominent osteoclast-like giant cells, either intimately admixed with the spindly cells (number=6) or forming giant cell tumor-like nodules (number=1). Immunohistochemically, the spindly cells expressed smooth muscle actin, muscle-specific actin, desmin and h-caldesmon in various degrees, whereas the osteoclast-like giant cells expressed CD68. Ultrastructural study showed smooth muscle differentiation in the spindly cells and histiocytic differentiation in the osteoclast-like giant cells. Follow-up data were available in 6 cases. There were local recurrences and/or metastases in all the 6 patients. Three patients were alive with unresectable or recurrent/metastatic disease and two patients died of the disease. Conclusions Leiomyosarcoma with prominent osteoclast-like giant cells is a rare variant of leiomyosarcoma which should be distinguished from the so-called giant cell variant of malignant fibrous histiocytoma. The osteoclast-like giant cells are of histiocytic differentiation. Surgical resection remains the mainstay of management of this high-grade sarcoma.     

Tumor progression in a giant cell type malignant fibrous histiocytoma of bone: Clinical,radiologic, histologic,and cytogenetic evidence

A malignant fibrous histiocytoma (MFH) of bone arising in the fibula of a 21-year-old woman is described. Clinical, radiologic, and histologic findings demonstrated rapid tumor progression. Chromosomal analysis of the biopsy specimen showed great karyotypic heterogeneity, whereas the resection specimen four weeks later displayed a rather homogeneous karyotype. Both revealed a clonal t(14;22)(q11;p12). Several other clonal and non-clonal chromosomal aberrations were observed. Some of these were previously described in giant cell tumor of bone (GCTB) and may correlate with aggressive behavior, e.g., aberrations involving 8p 11, 19q 13, and 20q 13. The change from karyotypic heterogeneity to relative homogeneity may be related to tumor progression. The chromosomal findings further suggest that the giant cell type of MFH of bone may be related to malignant GCTB. Genes Chrom Cancer 10:66–70 (1994). © 1994 Wiley-Liss, Inc.     

A diagnosis of giant cell-rich tumour of bone is supported by p63 immunohistochemistry,when more than 50 % of cells is stained

Some primary malignant or benign tumours of bone contain numerous multinucleated cells. These “giant cell-rich tumours of bone” have overlapping features and clinical and radiological data are needed to reach an accurate pathological diagnosis. We studied the potential contribution of p63 immunohistochemistry to the reliability of the histological diagnosis. We performed a multicentric retrospective study of 291 giant cell-rich tumours of bone which included 119 giant cell tumours of bone (GCTB), 76 aneurysmal bone cysts (ABC), 49 chondroblastomas (CB), 15 nonossifying fibromas (NOF), 10 giant cell reparative granulomas (RG) of jaws, 1 giant cell lesion of small bones, 2 hyperparathyroidism-related brown tumours (BT), 17 bone sarcomas with numerous osteoclasts and 2 malignant giant cell tumours of bone. p63 is expressed in ABC, CB, NOF, RG, BT and GCTB, but its expression in more than 50 % of mononuclear cells is strongly suggestive of a diagnosis of GCTB. In contrast, malignant GCTB were mostly negative. Our results show that p63 is expressed in a broad range of benign giant cell-rich tumours of bone, consistent with data in the recent literature, while infrequent in malignant tumours. With a cut-off 50 %, the presence of p63 positive cells is useful in supporting a diagnosis of giant cell-rich tumour of bone. However, a final diagnosis cannot be made without due consideration of all clinical/radiological and pathological data.     

H3.3 G34W突变抗体在骨巨细胞瘤中的表达及诊断价值

目的探讨H3.3 G34W突变抗体在骨巨细胞瘤(GCTB)中的表达情况及其对GCTB诊断的作用。方法收集解放军东部战区总医院病理科2001年6月至2019年4月诊断的83例GCTB、18例动脉瘤样骨囊肿、23例软骨母细胞瘤和28例骨肉瘤病历资料,采用免疫组织化学EnVision法检测H3.3 G34W突变抗体和p63的表达情况。结果83例GCTB中,69例(69/83)显示H3.3 G34W阳性,阳性率为83.1%,H3.3 G34W染色仅见于单核肿瘤细胞的细胞核,呈弥漫强阳性表达。H3.3 G34W在57例发生于长骨的GCTB中表达的阳性率为96.5%(55/57),而在26例发生于非长骨的GCTB中阳性率仅为53.8%(14/26)。所有复发(9/9)或转移性GCTB(2/2)、denosumab治疗后GCTB(3/3)、原发性恶性GCTB(3/3)和继发性恶性GCTB(5/5)均为H3.3 G34W阳性。所有动脉瘤样骨囊肿和软骨母细胞瘤均为H3.3 G34W免疫组织化学染色阴性。28例骨肉瘤中,H3.3 G34W的阳性率为10.7%(3/28)。富于巨细胞的骨肉瘤(GCRO)是骨肉瘤中唯一表达H3.3 G34W的组织学亚型。p63在71.1%(59/83)的GCTB中表达,而在动脉瘤样骨囊肿、软骨母细胞瘤和骨肉瘤中的阳性比例分别为3/18、43.5%(10/23)和21.4%(6/28)。H3.3 G34W突变抗体在GCTB诊断中的灵敏度和特异度分别为83.1%和95.7%。结论H3.3 G34W突变抗体是诊断GCTB高度灵敏和特异的标志物,有助于与具有相似形态学的骨肿瘤的鉴别。该抗体的局限性是少数存在G34突变但不是G34W突变的GCTB不能被检测出。骨肉瘤中H3.3 G34W突变蛋白的偶然表达可能是一个潜在的诊断难题,该免疫组织化学结果需谨慎解释。     

L‐type amino acid transporter‐1 and CD98 expression in bone and soft tissue tumors

L‐type amino acid transporter‐1 (LAT1) is expressed in many cancers. We examined LAT1 and CD98 expression immunohistochemically in surgically resected specimens of various bone and soft tissue tumors. Out of 226 cases, 79 (35%) were LAT1⁺ and 95 (42%) were CD98⁺. In bone tumors, LAT1 was highly expressed in osteoblastoma (89%), chondrosarcoma (50%), and osteosarcoma (60%); in soft tissue tumors, LAT1 was highly expressed in rhabdomyosarcoma (80%), synovial sarcoma (63%), Ewing's sarcoma (60%), epithelioid sarcoma (100%) and angiosarcoma (100%). In malignant soft tissue tumors, LAT1 expression was associated with higher histological grade. High CD98 expression was seen in many bone tumors of intermediate and high malignancy. Among soft tissue tumors, CD98 was expressed in tendon sheath giant cell tumor and malignant peripheral nerve sheath tumor (57%), Ewing's sarcoma (50%) and undifferentiated sarcoma (64%). Some of the malignant soft tissue tumors expressed both LAT1 and CD98. This study showed that LAT1 and CD98 was expressed in many malignant and intermediate bone tumors, and some malignant soft tissue tumors.     

Malignant fibrous histiocytoma of bone: a study of 35 cases.

Thirty-five cases of primary malignant fibrous histiocytoma of bone are reported. Twenty of these cases were collected from a retrospective analysis of other malignant bone tumors. The age range was from 11 to 69 years; the average age was 34 years. The tumor occurred most commonly in the distal femur and proximal tibia. The distinguishing histologic feature was a storiform arrangement of spindle cells. The differential diagnosis included fibrosarcoma, osteogenic sarcoma, malignant giant cell tumor, malignant lymphoma, and metastatic carcinoma. Follow-up of at least three years was available in 21 cases. Of these, nine patients were alive and free of metastases three and one-half to 12 years after treatment. Two were alive with solitary metastases at three years, and 10 patients died between three months and three years after treatment. In four cases the lesions were multicentric at the time of diagnosis and in four cases were associated with bone infarction. This tumor must be recognized as an important complication of bone infarction and should be suspected when a patient with a known history of bone infarction develops a change in symptoms. Because the prognosis of this tumor is significantly better than that in those tumors with which it had been previously grouped, and in view of its association with bone infarction, it deserves to be maintained as a distinct clinicopathologic entity. Amputation is the treatment of choice.     

Clinicopathologic features and immunohistochemical spectrum of 11 cases of epithelioid malignant peripheral nerve sheath tumors,including INI1/SMARCB1 results and BRAF V600E analysis

Epithelioid malignant peripheral nerve sheath tumor (MPNST) is a rare, relatively less chemosensitive sarcoma. We report clinicopathologic features of 11 epithelioid MPNSTs, including rare forms, along with INI1 immunostaining and BRAF V600E mutation results. BRAF V600E mutation was tested by Real‐time polymerase chain reaction (PCR) technique. Eleven tumors occurred in six men and five women (M:F ratio = 0.85:1) within an age range of 5–73 years (average = 44), mostly in lower limbs (five), followed by upper limbs (four). Tumor size (n = 6), varied from 3.1 to 15 cm (average = 8.3). Histopathologically, most tumors were multilobular, characterized by epithelioid to round‐shaped, malignant cells, along with spindle cells (three cases), “rhabdoid‐like” cells (seven cases) and pleomorphic giant cells (single case). By immunohistochemistry, tumor cells were positive for S100 protein (11/11) (100%), EMA (3/7) (42.8%), pan CK(2/7) (28.5%), and HMB45 (1/11) (9%), while these were negative for Melan A (0/11) and INI1 (3/11), including a single tumor, displaying HMB45 positivity. BRAF V600E mutation was positive in 1/8 cases, that lacked melanocytic marker expression. All patients (n = 5) were treated by surgical resection. During follow‐up (n = 8, median duration = 23 months), four patients developed tumor recurrences and four developed metastasis, mostly to lymph nodes (3). Finally, four patients were alive with disease, two were alive with no evidence of disease, and two patients died of disease. Epithelioid MPNSTs have a diverse histopathologic spectrum. Loss of INI1 is useful, including in identifying rare forms of epithelioid MPNST, displaying melanocytic differentiation. Most tumors are treated by surgical resection. Loss of INI1 and the presence of BRAF V600E mutation in some cases raises future possibility of exploring targeted therapy in those, rare epithelioid MPNSTs.     

p53 mutations may be involved in malignant transformation of giant cell tumor of bone through interaction with GPX1

Giant cell tumor of bone (GCTB) is a benign tumor with a tendency for local recurrence. Secondary malignant GCTB is rare, occurring in less than 2 % of GCTB cases. Mechanisms of malignant transformation of GCTB remain unclear. We examined 43 cases of GCTB (38 conventional cases, two lung implantation cases, and three secondary malignant cases) for p53 gene mutations and for loss of heterozygosity (LOH) of p53 when corresponding normal tissue was available. In addition, to elucidate the possible involvement of p53, GPX-1, cyclinD1, and Ki-67 in malignant transformation of GCTB, we assessed the expression of these proteins by immunohistochemistry. Mutations or LOH of p53 were found in all three malignant cases, which also showed p53 overexpression. Non-synonymous p53 mutations were detected in seven of 38 conventional cases (18 %), although none of these showed p53 overexpression, defined as more than 10 % of cells being positive. LOH at the p53 locus was detected in eight of 37 informative cases, although this was not associated with p53 overexpression in conventional GCT. Expression of GPX-1 was higher in the recurrent group, which included metastatic and malignant cases, and patients with high GPX-1 expression were at greater risk for early relapse. We also observed a positive correlation between high p53 expression and high GPX-1 expression in GCTB. Given that GPX-1 is shown to be a target of p53, these results suggest that p53 mutations play a role in tumor recurrence and malignant transformation of GCTB through interactions with GPX-1.     

Giant cell tumor of major salivary glands: report of three cases, one occurring in association with a malignant mixed tumor

Three cases of a heterofore undescribed neoplasm of major salivary glands morphologically similar to giant cell tumor of bone are presented. All tumors were located in the parotid gland of adult individuals, and all patients are alive and well following surgical excision. One of the three cases was associated intimately with a malignant mixed tumor (carcinoma in pleomorphic adenoma). Ultrastructural and immunohistochemical studies failed to provide conclusive evidence about the specific nature of the tumor cells. The major salivary glands should be added to the long list of organs in which extraskeletal giant cell tumors have been observed, whether alone or in association with an epithelial malignancy.     

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.     

Phenotypic and molecular studies of giant-cell tumors of bone and soft tissue

Giant-cell tumor of bone (GCTB) and giant-cell tumor of soft tissue (GCTST) are tumors that contain a prominent osteoclastlike giant-cell component. The precise relationship between these morphologically similar tumors is unclear, and the cellular mechanism whereby giant cells accumulate within these and other locally aggressive tumors is uncertain. In this study, we have examined the cytochemical, functional, and molecular phenotype of the mononuclear and multinucleated components of GCTB and GCTST. Giant cells in GCTB and GCTST exhibited an osteoclast phenotype expressing tartrate-resistant acid phosphatase and vitronectin receptor and being capable of lacunar resorption. The mononuclear stromal cells derived from GCTB and GCTST exhibited an osteoblast phenotype, expressing alkaline phosphatase, and the receptor activator for nuclear factor kappaB ligand (RANKL), a factor that is essential for osteoclast formation. These cells also expressed osteoprotegerin (OPG), an inhibitor of osteoclastogenesis, and TRAIL, a receptor that binds OPG. Lacunar resorption by giant cells isolated from GCTB and GCTST was inhibited by OPG, zoledronate, and calcitonin. These findings indicate that the mononuclear and giant-cell components of GCTB and GCTST have similar phenotypic features and that the accumulation of osteoclasts in these giant-cell-rich tumors occurs by a RANKL-dependent process. RANKL expression by osteoblastlike mononuclear stromal cells in these tumors stimulates osteoclast formation and resorption; this would account for the osteolysis associated with these giant-cell-rich tumors. Inhibitors of osteoclast formation and activity are likely to be effective in controlling the osteolysis associated with GCTB and possibly other giant-cell-rich lesions.     

Cytogenetic analysis of 101 giant cell tumors of bone: Nonrandom patterns of telomeric associations and other structural aberrations

Giant cell tumor of bone (GCTB) is a benign but locally aggressive tumor with metastatic potential. We performed cytogenetic analysis on 101 GCTB from 92 patients. Karyotypes were obtained from 95 tumors, 47 of which had clonal aberrations. The majority of the cytogenetically abnormal GCTB had multiple, up to 28 per tumor, clones. Clonal telomeric associations (tas) and other structural and numerical changes were found in about 70, 60, and 30%, respectively, of clonally abnormal tumors. Forty‐seven aberrations were recurrent, of which 35 are novel. The vast majority of the recurrent aberrations were tas, confirming the important role of telomeric fusions in the development of GCTB. The frequency of tas in GCTB cultures increased with passaging, suggesting a selective advantage of tas‐positive cells in vitro. The termini most frequently involved in tas were 22p, 13p, 15p, 21p, 14p, 19q, 1q, 12p, 11p, and 20q. The frequency of tas (irrespective of their clonality) was significantly higher in tumors carrying clonal changes, indicating that tas are precursors of other types of aberrations. In line with this assumption, the chromosomes preferentially involved in tas in a given tumor were also the ones most often affected by other rearrangements. We did not find the previously reported amplicon in 20q11.1, assessed by fluorescence in situ hybridization in 10 tumors. Nor did we find any association between cytogenetic features and adverse clinical outcome. Thus, local recurrences probably depend more on the adequacy of surgical treatment than on the intrinsic biology of the tumors. © 2009 Wiley‐Liss, Inc.     

Genomic instability in giant cell tumor of bone. A study of 52 cases using DNA ploidy,relocalization FISH,and array‐CGH analysis

Genetic instability in relation to clinical behavior was studied in 52 cases of giant cell tumor of bone (GCTB). Ploidy was determined in the mononuclear cell population by using native cell smears and image cytometry. A relocalization technique allowed fluorescent in situ hybridization (FISH) analysis of CD68‐negative neoplastic cells for numerical changes of chromosomes X, 3, 4, 6, 11, and telomeric association on 11p. Genome‐wide alterations were tested using array comparative genomic hybridization (array‐CGH) on magnetically separated CD68‐negative tumor cells. CTNNB1, TP53, and BCL2 protein expression was also analyzed in formol‐paraffin sections to see if their pathways are involved in the development of chromosomal instability. CD68‐positive histiocytes showed no significant numerical chromosome and telomeric alterations. Based on ploidy values and clinical outcome, we could distinguish five groups as follows: diploid nonrecurrent (n = 20), tetraploid nonrecurrent (n = 6), diploid recurrent (n = 5), tetraploid and/or aneuploid recurrent (n = 14), and malignant cases (n = 7). Random individual‐cell aneusomy was significantly (P < 0.001) more frequent in the recurrent groups (36.01 ± 11.94%) than in the benign nonrecurrent cases (10.65 ± 3.66%). The diploid recurrent group showed significantly (P < 0.001) increased balanced aneusomy compared with the diploid nonrecurrent group and the tetraploid nonrecurrent group represented eusomic polysomy. Array‐CGH and FISH showed clonal aberrations almost exclusively in the malignant group. None of the protein markers tested showed significant correlation with elevated aneuploidy/polysomy (P = 0.56). Our results show that ploidy determination combined with FISH analysis may help predicting recurrence potential of GCTB and suggest that chromosomal abnormalities superimposed on telomeric associations could be responsible for an aggressive clinical course. © 2009 Wiley‐Liss,Inc.     

Low-grade fibromyxoid sarcoma with prominent giant rosettes and heterotopic ossification

Low-grade fibromyxoid sarcoma is a rare soft tissue sarcoma of fibroblastic differentiation characterized by a deceptively benign morphologic appearance with almost consistent MUC4 expression and recurrent chromosomal translocations, t(7;16)(q34;p11) and t(11;16)(p11;p11), resulting in the FUS-CREB3L2 and FUS-CREB3L1 fusion genes, respectively. A subset of the tumors show peculiar histologic features, designated as giant rosettes, and were formerly referred to as hyalinizing spindle cell tumor with giant rosettes. We herein report a case of low-grade fibromyxoid sarcoma showing the presence of numerous giant rosettes, with and without collagenous centers, distributed throughout the lesion and unusual rim-like heterotopic ossification. Such a case might present a diagnostic challenge. The diagnosis of the tumor was confirmed by positive immunoreactivity to MUC4 and the FUS-CREB3L2 fusion detected by molecular testing using formalin-fixed, paraffin-embedded tissue. This case, which has such unusual clinicopathologic features, would help to further expand our knowledge regarding the morphologic diversities of low-grade fibromyxoid sarcoma.     

Smooth muscle actin expression in primary bone tumours

Alpha isoform of smooth muscle actin (SMA) expression has been reported in giant cell tumour of bone (GCTB) and other benign and malignant bone tumours, but the pattern of SMA expression and the precise nature of SMA-expressing cells in these lesions is uncertain. We determined by immunohistochemistry the expression of SMA and other muscle and vascular markers in normal bone, GCTB and a wide range of primary benign and malignant bone tumours. Cultured stromal cells of GCTB, chondroblastoma (CB), and aneurysmal bone cyst (ABC) were also analysed for SMA expression. SMA was only noted in blood vessels in normal bone. SMA was expressed by mononuclear stromal cells (MSC) cultured from GCTB, ABC and CB. SMA was strongly and diffusely expressed by MSC in non-ossifying fibroma, fibrous dysplasia, and "brown tumour" of hyperparathyroidism. SMA expression was also noted in GCTB, ABC, CB, chondromyxoid fibroma, malignant fibrous histiocytoma of bone and osteosarcoma. Little or no SMA was noted in Langerhans cell histiocytosis, simple bone cyst, Ewing's sarcoma, osteoblastoma, osteoid osteoma, enchondroma, osteochondroma, chondrosarcoma, myeloma, lymphoma, chordoma and adamantinoma. Our findings show that there is differential SMA expression in primary bone tumours and that identifying the presence or absence of SMA is useful in the differential diagnosis of these lesions. The nature of SMA-expressing cells in bone tumours is uncertain but they are negative for desmin and caldesmon and could represent either myofibroblasts or perivascular cells, such as pericytes.     

Epidermal growth factor receptor signalling contributes to osteoblastic stromal cell proliferation, osteoclastogenesis and disease progression in giant cell tumour of bone

Balla P, Moskovszky L, Sapi Z, Forsyth R, Knowles H, Athanasou N A, Szendroi M, Kopper L, Rajnai H, Pinter F, Petak I, Benassi M S, Picci P, Conti A & Krenacs T
(2011) Histopathology 59 , 376–389 Epidermal growth factor receptor signalling contributes to osteoblastic stromal cell proliferation, osteoclastogenesis and disease progression in giant cell tumour of bone Aims: Epidermal growth factor receptor (EGFR) is implicated in bone remodelling. The aim was to determine whether EGFR protein expression contributes to the aggressiveness and recurrence potential of giant cell tumour of bone (GCTB), an osteolytic primary bone tumour that can exhibit markedly variable clinical behaviour. Methods and results: Immunohistochemical analysis on tissue microarrays (TMA) of 231 primary, 97 recurrent, 17 metastatic and 26 malignant GCTBs was performed using TMA analysis software and whole digital slides allowing validated scoring. EGFR expression was restricted to neoplastic stromal cells and was significantly more frequent in recurrent (71 of 92; 77%) than in non‐recurrent GCTBs (86 of 162; 53%) (P = 0.002); and in clinicoradiologically aggressive (31 of 43; 72%) than latent (27 of 54; 50%) cases (P = 0.034). Detecting phosphotyrosine epitopes pY1068 and ‐pY1173 indicated active EGFR signalling, and finding EGFR ligands EGF and transforming growth factor‐α restricted to cells of the monocytic lineage suggested paracrine EGFR activation in stromal cells. In functional studies EGF supported proliferation of GCTB stromal cells, and the addition of EGF and macrophage‐colony stimulating factor promoted osteoclastogenesis. Conclusion: In GCTB, EGFR signalling in neoplastic stromal cells may contribute to disease progression through promoting stromal cell proliferation and osteoclastogenesis.