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Background/aim Clear cell sarcoma (CCS) of soft tissue is exceedingly rare and frequently exhibits aggressive behavior. Toward the goals of improving the aggressive course and poor prognosis of CCS, and establish new therapeutic methods, molecular genetic and biological characterizations of CCS are required. Materials and methods A new human CCS cell line (designated RSAR001) was established from the pleural effusion of a 44-year-old man with multiple lung metastases and pleural dissemination. The cell line and its xenograft were characterized including their morphology, immunohistochemistry, cytogenetic analysis, reverse transcription-polymerase chain reaction, direct sequencing analysis, and fluorescence in situ hybridization analysis. Results The cell line has been maintained for over 12 months with more than 50 passages. RSAR001 cells exhibited a fascicular or diffuse growth pattern of short spindle- or oval-shaped cells with clear cytoplasm in heterotransplanted tumor, that was similar to the primary tumor. Immunophenotypically, RSAR001 cells in vitro and in vivo exhibited almost the same characteristics as the primary tumor. Cytogenetic analyses revealed a translocation, t(12;22)(q13;q12). Reverse transcription-polymerase chain reaction and direct sequencing analysis detected transcripts of the Ewing sarcoma breakpoint region 1-activating transcription factor 1 (EWSR1-ATF1) type 1 fusion gene. Fluorescence in situ hybridization using a break-apart probe for the EWSR1 gene on 22q12 showed a rearrangement. Conclusion These findings indicate that the RSAR001 cell line harbors EWSR1-ATF1 type 1 chimeric fusion gene, which is specific to CCS. RSAR001 cells might be useful for investigating biological behaviors and developing new treatments such as molecular-targeting antitumor drugs or immunological drugs for CCS.

Functional reconstruction following a wide resection for a malignant musculoskeletal tumor is often challenging, particularly for juxta-articular tumors. The current study describes a novel surgical procedure for the functional reconstruction of the knee extensor mechanism with a pedicle frozen auto-bone and -tendon graft, in a case of prepatellar clear cell sarcoma. The active range of motion of the knee was from 0–135°, and the extension muscular strength of the knee was evaluated as 5/5 by a manual muscle test at 14 months post-surgery (International Society of Limb Salvage score, 73%); this was improved compared with a similar procedure previously described by Muramatsu et al. This procedure must be considered following the wide resection of juxta-articular malignant musculoskeletal tumors.

Purpose : This study investigated the shape of bone grafts and associations with upper limb function over the long term after free vascularized fibular head graft (FVFHG) for reconstruc- tion of the proximal humerus after wide resection for bone sarcoma. Methods : Patients comprised 3 women who had undergone FVFHG at least 5 years previous- ly. Age at surgery was 12 years in 2 cases and 76 years in one. The mean follow-up periods were 10 years 4 months. Evaluated parameters comprised : 1) graft hypertrophy, and 2) shape of the fibular head as changes in shape of the bone graft ; and 3) ISOLS score, and 4) DASH score as indi- cators of upper limb function. Results : Rates of graft hypertrophy of the fibular shaft were −14%, −17%, and −20%, respective- ly, with transverse diameter decreasing in all cases. In terms of changes in shape of the grafted fib- ular head, transverse diameter had diminished in 2 patients (−5 mm and −2 mm), and the head had been completely resorbed in the remaining patient. Both patients in whom the fibular head re- mained were young, and both had good ISOLS scores >80% and good DASH scores of 5.0 and 8.3. The patient in whom the fibular head had been resorbed was elderly, with ISOLS and DASH scores of 73.3% and 34.2, respectively ; comparatively poor compared with the other two. A com- parison of ISOLS and DASH scores before and after fibular head resorption, however, showed no de- terioration in either score. Conclusions : Long-term follow-up of humerus reconstruction by FVFHG showed no deteriora- tion in upper limb function despite the risk of fibular head resorption. FVFHG of the proximal hu- merus is a reconstruction technique that can provide good long-term upper limb function.

Background: To provide patients with a superior quality of life (QOL) after their pelvic tumor resection, ensuring the stability of the trunk as well as satisfactory lower extremity function is important. Although microsurgical reconstructions for the pelvic ring and hip are used clinically, the details of postoperative long-term spinal deformity and QOL remain unclear. Methods: The patients were 66- and 43-year-old men and a 43-year-old woman. The mean postoperative follow-up period was 134 months. The surgical procedures performed on these patients were: pelvic ring reconstruction using a double-barreled free vascularized fibular graft (FVFG) in Patient 1; simultaneous pelvic ring reconstruction using FVFG and hip arthrodesis in Patient 2; and latissimus dorsi free flap without pelvic ring reconstruction in Patient 3. As indicators of spinal deformity, we measured the Cobb angle, thoracic kyphosis angle, lumbar lordosis angle, pelvic angle on the sagittal plane, and sagittal plane balance using whole spine radiography. To assess the patients’ QOL, we examined the International Society of Limb Salvage (ISOLS) score, the Roland-Morris Disability Questionnaire (RDQ), activities of daily living (ADL) satisfaction using a visual analogue scale (VAS), and the SF-36. Results: Spinal alignment in the frontal plane worsened in order from Patient 1 to 3. Spinal alignment and pelvic tilt in the sagittal plane were at appropriate levels in Patients 1 and 2. The trunk tilt in the sagittal plane was at an appropriate level only in Patient 1. In the QOL assessment, the function of the affected limb worsened in order from Patient 1 to 3. RDQ scores were lower than the national norm in Patients 2 and 3. With respect to ADL satisfaction and the SF-36, Patient 3 had a markedly low VAS, physical functioning, role-physical, and role-emotional scores. Conclusion: In the long-term clinical course after pelvic tumor resection, in order to obtain satisfactory spinal alignment and QOL, pelvic ring reconstruction and hip arthrodesis are important.

Objective: To describe a rare case of remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome caused by gouty arthritis. Clinical Presentation and Intervention: A 76-year-old man presented with swelling and pain in the dorsum of feet and hands bilaterally. From the laboratory and radiologic findings, the diagnosis of gout-induced RS3PE syndrome was made. Conservative therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) and intra-articular corticosteroid injection in the wrist joint completely and rapidly resolved all symptoms. The patient was successfully treated with oral administration of NSAIDs and a one-time intra-articular corticosteroid injection in the left wrist joint. Conclusion: This case demonstrated the importance of considering the possibility of crystal-induced arthritis such as gout and pseudogout, as well as malignant disease, when diagnosing the primary disease responsible for RS3PE syndrome.

Although calcium pyrophosphate dehydrate (CPPD) deposition disease, including pseudogout, is a relatively common disease affecting the major joints, especially the knee, pseudogout in the acromioclavicular (AC) joint is very uncommon. We describe two cases of acute pseudogout attacks of the AC joint in elderly patients. Radiological findings showed chondrocalcinosis in the AC joints. Microscopically, aspirated articular synovial fluid demonstrated CPPD crystals. Conservative therapy with non-steroidal anti-inflammatory drugs completely resolved all symptoms within 1 week.

Objective: Dedifferentiated liposarcomas usually occur in the retroperitoneal space and relatively rarely in the extremities. Methods: We identified 18 patients with primary dedifferentiated liposarcoma in the extremities from the files of Tohoku Musculoskeletal Tumor Society and analyzed demographics, histologic findings, treatments and prognostic factors. The average follow-up period was 58 months. Results: The subjects were 12 men and 6 women with a mean age of 65 years. All tumors were in the thigh. Nine patients noticed a rapid enlargement of the long-standing tumor. Histologic subtypes of the dedifferentiated area were undifferentiated pleomorphic sarcoma (n ¼ 12), osteosarcoma (n ¼ 2), rhabdomyosarcoma (n ¼ 2), leiomyosarcoma (n ¼ 1) and malignant peripheral nerve sheath tumor (n ¼ 1). In the patient with rhabdomyosarcoma-like dedifferentiated area, extensive necrosis was observed after the preoperative chemotherapy. One patient who underwent marginal excision developed a local recurrence, but inadequate surgical margin was not associated with a risk of local recurrence. Three patients had lung metastasis at initial presentation, and four other patients developed lung metastases during the follow-up period. The overall survival rate was 61.1% at 5 years. On univariate analyses, large size of the dedifferentiated area (.8 cm), high MIB-1-labeling index (.30%) for the dedifferentiated area and lung metastasis at initial presentation were significantly associated with poor prognosis. Conclusions: Primary dedifferentiated liposarcoma in the extremities predominantly occurred in the thigh and a rapid enlargement of long-standing tumors was a characteristic symptom. Although the local behavior of these tumors was less aggressive than that of retroperitoneal dedifferentiated liposarcomas, they had a relatively high metastatic potential.

We describe herein a rare case of primary rhabdomyosarcoma (RMS) occurring in the sacrum. A 16-year-old woman presented with a 2-month history of pain in bilateral buttocks and posterior thighs. Computed tomography showed a primary tumor with bone destruction in the 2nd sacral vertebra and invasion to the 1st to 3rd vertebrae and retroperitoneal space. Histological examination of the tumor showed proliferation of spindle-shaped cells intermingled with rhabdomyoblasts in a fascicular and storiform growth pattern. Tumor cells showed immunoreactivity for vimentin, desmin, muscle-specific actin, sarcomeric actin, alpha-smooth muscle actin and CD99, and partial immunoreactivity for myoD1, myf-4, myogenin and myoglobin. Reverse transcription polymerase chain reaction demonstrated expression of myoD1. On the basis of the aforementioned findings, a poorly differentiated spindle cell variant of embryonal RMS was diagnosed. The patient underwent combined therapy with chemotherapy and radiotherapy, but died 17 months after incisional biopsy. The present case is instructive in differential diagnosis of primary bone tumors, and the possibility of skeletal RMS needs to be considered.

Background Lipoma-like liposarcomas mimic deep-seated lipomas in regard to imaging as well as histological findings and occasionally cause problems concerning diagnosis and treatment. The differences in the imaging findings among these lesions are not well defined. The purpose of this study was to elucidate the differences among the deep-seated adi-pocytic neoplasms including intramuscular lipoma, intermuscular lipoma, and lipoma-like liposarcoma. Methods The imaging and clinicopathological findings of 40 intramuscular lipomas, 27 intermuscular lipomas, and 22 lipoma-like liposarcomas were evaluated, and the possibilities in the differential diagnosis were assessed. Results Although the most frequent symptom was a palpable mass, swelling was a common symptom of intramuscular lipomas and lipoma-like liposarcomas. Imaging studies revealed dumbbell-shaped appearances among intermuscular lipomas, whereas spherical masses were characteristic of intramuscular lipomas and lipoma-like liposarcomas. Computed tomography and magnetic resonance imaging revealed fatty lesions containing streaky structures in benign lesions, and CT revealed foci of hazy amorphous density, representing spindle cell proliferation, in lipoma-like liposarcoma. Although streaky structures corresponding to entrapped muscle fibers were thick and occasionally interrupted in intramuscular lipomas, the streaky structures corresponding to areolar fibrous tissue were thin and were usually not interrupted in intermuscular lipomas. In lipoma-like well-differentiated liposarcomas, thick streaks represented entrapped muscle fibers, and thin streaks represented fibrous tissue or neoplastic spindle cell proliferation. Conclusions The imaging findings are helpful and often afford almost pathognomonic evidence of these lesions and could help with the selection of appropriate surgery.

Ewing sarcoma family of tumors (ESFT) comprise common sarcomas in children and young adults. Such tumors usually occur in the medullary cavity of long bones and directly invade cortical bone and circumferential soft tissue, including periosteum. Periosteal ESFT is extremely rare and only a small numbers of cases, including cases not confirmed by molecular detection of chimeric fusion gene, have been reported. We describe herein a case of periosteal ESFT of the femur in a 13-year-old boy harboring EWS-FLI1 chimeric fusion gene transcripts detected by reverse transcription-polymerase chain reaction analysis. This report may provide an opportunity for further evaluation of the EWS-FLI1 type 1 fusion gene and detection of prognostic significance in periosteal ESFT.

We describe herein two tumor-induced osteomalacia (TIO) cases for whom the causative lesions, located in their popliteal fossa, that were not identified in the standard field of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT), which usually images only the head, trunk, and proximal parts of the extremities.A 47 years old Japanese man with multiple pathological fractures due to osteomalacia, accompanied by muscle weakness, hypophosphatemia, and an elevation of alkaline phosphatase (ALP) was referred to our hospital. A (18)F-FDG PET/CT scan was performed, but no (18)F-FDG uptake was detected in the standard field of imaging. Magnetic resonance imaging revealed a small subcutaneous tumor (1.9×1.2×0.6cm) of the left posteriomedial knee, displaying uniform enhancement on gadolinium-enhanced T1-weighted fat-suppression imaging. The tumor was resected widely and diagnosed as phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT). The other patient was a 31 years old Japanese woman with multiple pathological fractures, hypophosphatemia and elevated of ALP and was referred to our hospital on suspicion of TIO. Although the causative lesion was not identified in the standard field of (18)F-FDG PET/CT, (18)F-FDG uptake (SUVmax 2.9) was detected on the right knee in the additional whole-body (18)F-FDG PET/CT. Magnetic resonance imaging revealed a soft-tissue tumor (6.4×4.1×2.9cm) in the right posterior knee. Following biopsy, the tumor was marginally resected, and was pathologically diagnosed as PMTMCT.Once patients are suspected to have TIO, a whole-body nuclear imaging study such as (18)F-FDG PET/CT should be performed, in order not to miss the hidden causative tumor, especially occurring in the distal extremities.

Malignant peripheral nerve sheath tumor (MPNST) is a relatively rare soft tissue tumor, and its clinical relevance of pathological grades remains obscure. Fifty-six cases of MPNST identified from the files of seven oncology centers of the Tohoku Musculoskeletal Tumor Society (TMTS) and National Cancer Center were analyzed for histologic grades, demographics, treatments, and prognostic factors. The average follow-up period was 41 months. Twenty-two men and 34 women with a mean age of 45 years were involved. Forty-four (78.6%) of 56 tumors were in the lower extremity or trunk. Fifty tumors (89%) were classified as high grade, and the remaining six as low grade. Twenty-one (39.6%) of 53 patients who underwent tumor excision developed local recurrences. An axial site and inadequate surgical margin were defined as risk factors for local recurrence. The overall survival rates of the 56 patients were 55.1% at 3 years and 43.3% at 5 years. Univariate analysis of the 56 patients revealed large-sized tumors, metastasis at presentation, and histologically high grade were significantly associated with poor prognosis. Multivariate analysis revealed a large tumor and metastasis at presentation to be independent prognostic factors. The current study involving 56 patients with MPNST showed the aggressive clinical behavior of the tumor. Large-sized tumors, metastasis at presentation, and high histological grade were related to poor prognosis on univariate analysis, but independency of histological grade was still obscure. In the treatment for a large and high-grade MPNST, an alternative strategy should be further considered.

For percutaneous radiofrequency ablation of osteoid osteoma for pain management, we used a standard electrosurgical generator instead of the radiofrequency generator system. First, we used the standard electrosurgical generator to determine the diameter of the coagulated area of normal femurs and humeruses of dogs under general anesthesia and to detect damage to normal tissue around the bone. We then used a standard electrosurgical generator to perform percutaneous radiofrequency ablation of the osteoid osteoma. All three patients were almost pain-free within the first 24 h after the procedure, and they were discharged the day after the operation, being hospitalized for only 2 days. We thus confirmed that percutaneous radiofrequency ablation using a standard electrosurgical generator produced results similar to those achieved with the radiofrequency generator system.

Myxoid liposarcoma frequently occurs in the deep soft tissue of the extremities, particularly in the thigh. The present study describes an extremely rare case of primary dumbbell-shaped epidural myxoid liposarcoma of the thoracic spine occurring in a 22-year-old woman. Although preoperative magnetic resonance imaging findings were thought to be compatible with schwannoma, the pathological diagnosis of the resected tumor was myxoid liposarcoma. The patient underwent three courses of adjuvant chemotherapy with doxorubicin and ifosfamide, and exhibited no symptoms or signs of local recurrence or metastasis for 18 months post surgery. The present case suggests that, when radiologically diagnosing spinal epidural tumors, clinicians should consider the possibility of myxoid liposarcoma.

Myofibroblastic tumors are fairly recently established soft tissue neoplasms. Although most of them appear to be benign, myofibrosarcoma of the soft tissue, seemingly their malignant counterpart, have been reported. We describe the clinicopathologic and radiologic features of four cases of myofibrosarcoma arising from the bone. All but one of the patients were women ranging in age from 60 to 71 years. Two tumors occurred in the metaphyses of distal femurs and the others arose in the iliac bones. On radiologic examination all tumors exhibited well-demarcated lytic destructive lesions without periosteal reaction. Two tumors were localized in the bone, whereas the other two extended into surrounding soft tissues. Histologically, all tumors were composed principally of a mixture of a cell-rich fascicular area and a hypocellular fibrous area. In the former area tumor cells had rather eosinophilic spindle-shaped wavy cytoplasm and were arranged in interlacing fascicles and small storiform patterns with variable numbers of inflammatory cells. Tumors occasionally showed prominent pleomorphism, and large cells with hyperchromatic nuclei were seen. In contrast, hypocellular areas had various features, including collagenous, hyalinous scar-like and rarely keloid-like areas. Focal coagulation necroses were present in all but one tumor. Immunohistochemically, the tumors were positive for vimentin, muscle actin (HHF35), alpha-smooth muscle actin, calponin, and desmin, whereas all of them were negative for high molecular weight caldesmon. On follow-up there was one fatal case with distant metastases, whereas the clinical courses of other cases after wide resection were excellent. Myofibrosarcoma of the bone has distinctive histopathologic features, which should be distinguished from those of other bone tumors with myoid differentiation.

Although inflammatory myofibroblastic tumors, originally described in the lung, have recently been recognized to occur in various sites, their origin in bone is exceptional. We present a case of inflammatory myofibroblastic tumor, so-called inflammatory fibrosarcoma, of the bone. The tumor occurred in the iliac bone of a 70-year-old woman. Standard radiographs and magnetic resonance imaging revealed a destructive bone tumor that expanded into the soft tissue. Although the patient underwent excision of the hemi-iliac bone, multiple pulmonary metastases were noted 1 year after the operation. On histologic examination, the tumor was found to be composed of a sarcoma-like cellular area and a hypocellular fibrous area. Inflammatory cell infiltration into the tumor was a distinctive feature and is analogous with that of conventional inflammatory myofibroblastic tumor or inflammatory fibrosarcoma of the soft tissue. This is the first report to our knowledge of an inflammatory myofibroblastic tumor of the bone with distant metastasis.

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.

Although giant cell tumor (GCT) of bone is a well-recognized neoplasm with distinctive clinical and histopathological features, the origin of tumor cells, particularly of mononuclear cells, has not yet been established. An immunohistochemical study was carried out on 11 cases of GCT of bone to examine the cellular natures of stromal mononuclear cells. In all cases, stromal cells were positive for muscle actin (HHF35) or alpha-smooth muscle actin, and in eight of 11 cases, positivity was intense and extensive. The cell margin of osteoclast-like giant cells (OGC) was stained positively by muscle actin, in addition to intense and diffuse positive staining of the cytoplasm for KP1 (CD68), whereas alpha-smooth muscle actin exhibited a negative reaction on the OGC. In conclusion, the tumor cells with muscle actin and alpha-smooth muscle actin positivities are not rare but frequently numerous in the GCT of bone; whereas further observation is necessary to elucidate whether the stromal cells exhibit myofibroblastic cell differentiation exactly.

Alveolar rhabdomyosarcoma (ARMS) is a subtype of rhabdomyosarcoma and usually occurs in childhood and adolescence. ARMS is characterized by its aggressive behavior and poor prognosis. To improve the unfavorable prognosis, new therapeutic developments and the establishment of methods for precise prognostic prediction are required. We describe a case of ARMS, solid variant, which occurred in a 10-year-old boy. After chemotherapy and radiotherapy, the tumor morphologically and immunohistochemically showed marked cytodifferentiation, whereas the exact same PAX3-FKHR chimeric fusion gene transcript was detected in samples before and after treatment. The result of this study seems to indicate that therapeutic cytodifferentiation does not always correlate with genetic change and favorable prognosis in ARMS.

Spindle cell hemangioma, a rare benign tumor characterized by cavernous blood vessels and spindled areas, typically arises in the subcutis of the distal extremities, particularly the hand. The case of intraosseous spindle cell hemangioma is extremely rare, and only 1 case arises in the frontal bone has been reported previously. We describe herein a case of intraosseous spindle cell hemangioma occurring in the left calcaneus in a 65-year-old woman. The patient was successfully treated by the operation. The present case is instructive especially in the differential diagnosis of primary bone tumor structured by spindle cells, for which the possibility of spindle cell hemangioma should be considered.

Castleman’s disease (CD), a rare benign disease characterized by lymphoid hyperplasia, typically arises in the mediastinum as a solitary tumor. We describe herein a rare case of intramuscular CD occurring in the left deltoid in a 28-year-old woman. The present case is instructive in the differential diagnosis of primary soft tissue tumors, for which the possibility of CD should be considered.

Malignant peripheral nerve sheath tumor (MPNST) is a rare soft tissue sarcoma. We established a new human MPNST cell line (designated FMS-1) from MPNST of the right brachial plexus of a 69-year-old woman with NF1. The cell line has been maintained for >24 months with >100 passages. FMS-1 cells showed a fibrosarcoma-like or epithelioid pattern in the heterotransplanted tumor, compared with a fascicular growth pattern of short-spindle tumor cells in the primary tumor. Immunophenotypically, FMS-1 cells showed almost the same characteristics as the primary tumor. Cytogenetic and molecular analyses revealed a deletion in exons 5-8 of the p53 gene. Epidermal growth factor receptor (EGFR) and cyclooxygenase (COX)-2 were expressed in FMS-1 cells. To improve the highly aggressive course and poor prognosis and establish new therapeutic methods, molecular genetic and biological characterizations of MPNST are required. Thus, FMS-1 cells might be useful for investigating biological behaviors and developing new molecular-targeting antitumor drugs for MPNST expressing EGFR or COX-2.

Ifosfamide encephalopathy is a central nervous system toxicity that occurs in patients treated with ifosfamide. Although it has been reported in European and American patients with various carcinomas, there have been no published reports regarding ifosfamide encephalopathy in Asian patients with bone and soft tissue sarcomas.We retrospectively examined the incidence, severity, and risk factors of ifosfamide encephalopathy in 61 Japanese patients with bone and soft tissue sarcomas at our institution.Ifosfamide encephalopathy occurred in 17 of 61 patients (31.2%) to whom ifosfamide was administered and in 29 of 214 ifosfamide treatment courses (13.6%). The most common symptoms of encephalopathy were "confusion," "somnolence," and "mood alteration - agitation." Severe encephalopathy occurred only in patients who received ifosfamide at dosesor=9 g/m(2). A history of cisplatin use was identified as a significant risk factor for the development of ifosfamide-induced encephalopathy.Because of the risk of severe encephalopathy, we conclude that patients who have previously received cisplatin or who receive ifosfamide at dosesor=9 g/m(2) require strict monitoring.

Fibronexus (fibronexus junction) has been thought to be a characteristic ultrastructural feature of myofibroblasts, but it is controversial as to whether fibronexus is a characteristic of various myofibroblastic tumors. We report here a case of low-grade myofibrosarcoma with fibronexus arising in the right arm of an 80-year-old man. Histologically, the tumor was composed of relatively uniform and slender spindle cells arranged in fascicles. The nuclei with fusiform and tapered shapes were mildly hyperchromatic, but never exhibited pleomorphism. Mitotic figures were common, but no atypical mitosis was identified. At the tumor periphery, tumor cells had invaded into the surrounding skeletal muscle tissue. Tumor cells were positive diffusely for alpha-smooth muscle actin and less intensely for desmin, but were negative for h-caldesmon and S-100 protein. Ultrastructurally, tumor cells had well developed cytoplasmic organelles and varying amounts of peripheral or subplasmalemmal bundles of thin myofilaments with focal density. In addition, well formed, long fibronectin fibrils adjacent to the cell surface and fibronexus contacting intracellular myofilaments were easily identified. We believe that fibronexus is a useful ultrastructural feature for differentiating myofibrosarcoma from other myogenic sarcomas.

Osteosarcoma is the most common form of malignant bone tumor that occurs during childhood and adolescence. The proximal fibula is a relatively rare site for osteosarcoma. We reviewed 305 cases of osteosarcoma registered at the Tohoku Musculoskeletal Tumor Society (TMTS) between 1975 and 1999. Thirteen patients (4.3%) had their osteosarcomas localized in the proximal fibula. Conventional fibroblastic osteosarcoma accounted for 46% of the cases in this series. Limb-sparing surgery was performed in all 13 patients during initial surgery, and the peroneal nerve was preserved in 4 cases. These 4 cases developed local recurrences, but additional wide excision or radiation had a beneficial effect on the recurrences. In our series, the patients showed a 5-year survival rate 76 per cent. The postoperative function of the knee remained good despite various reattachment procedures of lateral co-lateral ligament. As well as resection of the proximal fibula, our results indicate that osteosarcoma of the proximal fibula has a good prognosis for cases who undergo adequate initial surgery.

Undifferentiated pleomorphic sarcoma (UPS) is among the most common soft tissue sarcomas in adults. In order to improve its aggressive course or prognosis and establish new therapeutic methods, molecular genetic and biological characterizations of UPS are required.A new human UPS cell line (FPS-1) was established from UPS of the upper arm of a 79-year-old man. The cell line has been maintained for over 14 months with more than 60 passages. FPS-1 cells were characterized using molecular biological methods.FPS-1 cells showed the same morphological and immunophenotypical characteristics as the primary tumor. Cytogenetic and molecular analyses revealed a nonsense mutation in exon 6 of the p53 gene. Epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) were expressed in FPS-1 cells.FPS-1 cells might be useful for investigating biological behavior and developing new molecular targeting antitumor drugs for UPS with EGFR or COX-2 expression.

Ewing's sarcoma (ES) is a highly malignant tumor composed of uniform small round cells. Recently, a single biologic entity, Ewing's sarcoma family of tumors (ESFT) has been accepted. The entity includes ES, extraskeletal Ewing's sarcoma (EES) and primitive neuroectodermal tumor (PNET). ESFT cells have immunoreactivity for CD99, an antigen determined by the MIC2 gene. Most ESFT has the (11;22) (q24;q12) translocation. The translocation results in the fusion of the EWS gene with the transcription factor gene FLI1 which has been considered a hallmark of ESFT. We present an extremely unusual case with ESFT in a spinal nerve root mimicking a neurogenic dumbbell tumor. A male aged 20 years noticed pain in his right buttock. Magnetic resonance imaging (MRI) revealed a mass in the right L5/S intervertebral foramen and the lesions in the sacrum. Surgery was performed with a presumptive diagnosis of a nerve sheath tumor. At surgery, the tumor was located in the right L5 nerve root sleeve. The sacral lesions were observed closely. At one month after surgery, radiologically multiple lesions were detected in the pelvic bones. Microscopically the lesions from the root and ilium were composed of small round cells immunoreactive for CD99. Reverse transcription-polymerase chain reaction detected transcripts resulting from the fusion of the EWS gene with FLI1 genes in the iliac lesion. Immunoreactivity for CD99 and detection of the EWS-FLI1 hybrid transcripts are important for the correct diagnosis of ESFT arising in an unusual location.

The aims of this study were to investigate the anti-tumor effects of consecutive low-dose cisplatin (LD-CDDP) in comparison with single high-dose CDDP (HD-CDDP) in combination with caffeine.Human fibrosarcoma cells (HT-1080) were transplanted in BALB/C-nu mice. According to the administration of CDDP and caffeine, 5 groups were defined: HD-CDDP, LD-CDDP, HD-CDDP +caffeine, LD-CDDP +caffeine and control group. The total dose of CDDP was 3.5 or 6 mg/kg. CDDP was injected i.p. bolus (HD-CDDP) or divided into 5 days (LD-CDDP). Caffeine was injected i.p. at a dose of 60 mg/kg twice a day for 4 days.Significant inhibition of tumor growth and prolongation of survival time were recognized in the HD- and LD-CDDP groups with and without caffeine compared to the control group. The caffeine-assisted groups had no advantage compared to the CDDP alone groups.The effects of LD-CDDP were similar to the effect of HD-CDDP.

Background: The clinicopathologic profile and prognostic factors of osteosarcomas after the age of 50 years have been obscure. Methods: Clinicopathologic features were analyzed in 645 patients with osteosarcoma who were registered at the Tohoku Musculoskeletal Tumor Society and National Cancer Center in Tokyo between 1972 and 2002. Results: Sixty-four patients (9.9%; 34 men and 30 women) were more than 50 years old. The most common location was the distal femur (n = 13), followed by the pelvis (n = 10), proximal femur (n = 9), and proximal fibula (n = 6). Seven (11%) patients had lung metastasis at initial presentation. On radiographs, an osteolytic appearance without periosteal reactions was a common and characteristic feature. Forty-eight tumors (75%) were classified as conventional osteosarcomas. Fourteen cases (22%) were secondary; postradiation osteosarcoma was most common in these patients, but there was no Paget’s sarcoma. At the initial presentation, misdiagnoses without biopsy were made in 15 (23%) of the 64 cases. Preoperative chemotherapy was given to 22 patients, but the effect was poor in 18 cases (82%). Fifty-four patients underwent surgery, whereas the other 10 patients were treated without surgery because of systemic or inoperable local conditions. The overall survival rate at 5 years was 55.5%. Multivariate analysis showed initial pulmonary metastasis, axial tumor location, and larger tumors as significant prognostic factors. Conclusions: In northern Japan, most patients with osteosarcoma after the age of 50 had primary osteosarcoma. Careful radiological examination and biopsy are mandatory for correct diagnosis. Current systemic chemotherapy is not effective for this age group. Alternative treatment strategies should be considered.

We describe a case of giant cell tumor of the proximal tibia with skip bone metastases of the ipsilateral femur in a 20-year-old man. After the neoadjuvant treatment with denosumab, plain radiographs and computed tomography showed marked osteosclerosis and sclerotic rim formation, and 18F-FDG PET/CT showed a decreased standardized uptake value, whereas magnetic resonance imaging showed diffuse enhancement of the tumor, nearly the same findings as those at pretreatment. Pathological findings of the surgical specimen after the denosumab treatment showed benign fibrous histiocytoma-like features with complete disappearance of both mononuclear stromal cells and multinuclear osteoclast-like giant cells. Virtual Slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1090602085125068