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患者は78歳の女性.後腹膜の黄色肉芽腫で左腎摘出術を施行された既往がある.主訴は左下腹部痛で, 同部に一致して径10cmの腫瘤を触知し, 血液検査ではCEA とCA19-9が高値を示した. CTでは左後腹膜に石灰化を有し周囲に脂肪成分を伴う腫瘤を認めた.注腸造影では下行結腸は内側に圧排され, また盲腸に腫瘤陰影を認めた.2型盲腸癌と黄色肉芽腫の再発との診断で手術を施行した.下行結腸周囲の後腹膜腔に複数の腫瘤を認め, 迅速病理にてmyxoid sarcomaと診断されたため結腸左半切除術を施行し, また盲腸癌にて回盲部切除術を併施した.切除標本では漿膜下から後腹膜に黄褐色または灰白色な弾性硬の腫瘤を認めた. 組織学的には分化型の軟骨肉腫や骨肉腫, 平滑筋肉腫および脂肪肉腫の成分を認め悪性間葉腫と診断された.盲腸癌は2型の高分化腺癌でss, ly2, v0, n1 (+) であった. 本疾患はまれであり組織発生を検討する上で興味ある症例と考えられたので報告する

症例は46歳, 女性. 咳嗽と胸部異常陰影を主訴に来院した. 胸部単純X線写真では左胸腔に巨大な腫瘤を認めた。CTでは縦隔から左胸腔に多結節性の腫瘤が存在し, 内部は不均一で脂肪成分に富み, 一部石灰化を伴っていた. MRIでは腫瘤の大部分は脂肪組織の信号強度を示すが, 中等度信号強度の部分も混在していた. 腫瘍を含めて左肺全摘を行い切除した. 最終病理診断は脂肪肉腫成分と軟骨肉腫成分からなる悪性間葉腫であり, CT, MRIの画像所見は本症の病理組織学的特徴をよく反映していた. 悪性問葉腫は二種類以上の肉腫成分より構成される軟部組織腫瘍であるが, 縦隔に発生することは稀で, 本症例は貴重な症例と考えられた.

Malignant mesenchymoma of the left atrium obstructing the mitral orifice was revealed at autopsy in a 39-year-old woman with a history indicating mitral stenosis. Minor tumour nodules were found in the walls of the right and left ventricle together with a few distant metastases. Clinical findings in primary cardiac tumours and the rarity of primary malignant mesenchymoma of the heart are discussed.

Osteoliposarcoma are rare tumors of the bone. To our knowledge, so far only eight cases have been reported. Some of the reports have referred to these tumors as malignant mesenchymoma. We report a case of a male with osteoliposarcoma of the right femur who presented with pain and restricted movements of the right knee joint. Radiologically, a tumor in the lower end of the right femur was seen extending into the soft tissue. The biopsy was reported as osteosarcoma. The patient received three cycles of neo-adjuvant chemotherapy followed by limb-salvage surgery with provisions for a custom-made prosthesis. A histopathological study of the excision specimen revealed areas of pleomorphic liposarcoma with numerous osteoblasts associated with areas of osteoid surrounded by neoplastic cells. The final diagnosis was osteoliposarcoma. Only 21% tumor necrosis (effects of chemotherapy) was observed. Presently, 26 months following diagnosis, the patient is fine with no evidence of local recurrence or distant metastasis.

Malignant ectomesenchymoma is an uncommon neoplasm composed of neuroectodermal elements and one or more mesenchymal neoplastic elements. It is believed to arise from remnants of migratory neural crest cells (ectomesenchyme). The authors report the clinical and pathological findings of a 3-year-old girl with malignant ectomesenchymoma of the CNS. Embryogenesis of this tumor is discussed, and a review of the literature with 39 other cases is done.

We report the clinicopathologic and cytogenetic findings in an unusual case of primary liposarcoma of bone. A 16-year-old girl presented with a destructive, osteolytic tumor of the proximal humerus. Upon biopsy, the tumor was highly anaplastic and necrotizing and was initially considered to be consistent with osteosarcoma. Following chemotherapy, there was 100% tumor necrosis in the resection specimen. Twentyeight months later, solitary supraclavicular and pulmonary metastases appeared with the morphologic features of pleomorphic liposarcoma. Retrospective review of the bone biopsy showed scattered lipoblasts and no unequivocal malignant osteoid. Ghost-like remnants of necrotic liposarcoma were seen in the resection specimen. Cytogenetic analysis of a metastatic lesion showed complex karyotypic abnormalities. Awareness of the existence of primary bone sarcomas with lipogenic differentiation expands the differential diagnosis of malignant bone tumors including cases in the pediatric population. This is the first report of cytogenetic findings in this tumor.

Cardiac mesenchymoma is a rare malignancy with a dismal prognosis. We present a case of left atrial mesenchymoma, obstructing the mitral orifice. An emergent tumor resection with mitral valve replacement was performed. Few reports deal with emergency resection of cardiac malignancies with mitral valve replacement. Surgery is the only effective treatment modality.

A case of a malignant mesenchymoma with an unusual, vasoinvasive, metastatic behavior in a three-year-old, intact female basset hound is presented. Malignant mesenchymomas are rare neoplasms in humans and in dogs. No previous reports of a malignant mesenchymoma with vasoinvasive metastasis in the dog were found in the literature. The constituent neoplasms are discussed in relation to reports in the human and veterinary literature, and a potential etiology for this unique presentation is hypothesized.

With the aim of identifying objective cytogenetic-morphologic correlations, we evaluated 46 pleomorphic soft tissue sarcomas (mainly diagnosed originally as malignant fibrous histiocytomas) with clonal chromosome aberrations both cytogenetically and morphologically as part of an international collaborative study. By detailed histopathologic examination, most cases could be categorized into specific tumor types. Eight sarcomas were diagnosed as lipogenic (4 pleomorphic, 1 combined pleomorphic and myxoid/round cell, and 3 dedifferentiated liposarcomas), 19 as myogenic [11 leiomyosarcomas, 1 rhabdomyosarcoma, 4 myosarcomas not otherwise specified (NOS), and 3 probable myosarcomas NOS], 8 as myxofibrosarcomas, 1 as a malignant peripheral nerve sheath tumor, 1 as malignant mesenchymoma, 1 as extraskeletal osteosarcoma, I as sarcoma resembling proliferative fasciitis, and 7 as pleomorphic sarcomas NOS. In a three-grade system, 10 tumors were grade 2 and 36 were grade 3. The majority had highly complex karyotypes. A total of 24 recurrent abnormalities (defined by their presence in at least five cases) were detected: ring chromosomes, homogeneously staining regions (hsr) and/or double minute chromosomes (dmin), and structural rearrangement of 22 different chromosome bands or regions. The frequency and distribution of the recurrent karyotypic features were uneven. Grade 3 tumors displayed, on average, more aberrations per case than did grade 2 tumors. Nine of the selected abnormalities, including hsr/dmin and rearrangements of 19p13 and 19q13, were found only among the high-grade tumors. When the tumors were subdivided according to lineage of differentiation, the highest frequency of aberrations was seen in pleomorphic sarcomas NOS, followed by myxofibrosarcomas, myogenic sarcomas, and lipogenic sarcomas. None of the selected rearrangements was, however, specific for any of these subgroups. The sole consistent cytogenetic-morphologic association was that all three dedifferentiated liposarcomas had multiple abnormal clones, at least one of which contained supernumerary ring chromosomes. Due mainly to karyotype complexity, it therefore seems unlikely that cytogenetic analysis can assist in the differential diagnostic subclassification of pleomorphic sarcomas, nor was there any clear-cut indication that the karyotypic picture could be used to predict clinical outcome. Although the mean number of recurrent chromosome aberrations was almost twice as high in sarcomas that gave rise to metastases as among those that did not, no particular aberration was restricted to either of the two subgroups.

A malignant mesenchymoma with predominant leiomyosarcomatous component and significant chondrosarcomatous and focal osteosarcomatous elements is presented. Transitional areas with overlapping morphologic and immunohistochemical features were found between the smooth muscle and cartilaginous components. Stains for actin were strongly positive in leiomyosarcoma, and in scattered malignant chondrocytes. Malignant chondrocytes and scattered neoplastic smooth muscle cells were positive for S-100. Both components were strongly positive for p53. Ultrastructurally there were calcified particles in the matrix of both chondrosarcoma and leiomyosarcoma. These findings support the concept that malignant mesenchymoma results from divergent differentiation of primitive mesenchymal cell with pluripotential capability. A literature review of retroperitoneal malignant mesenchymomas with similar differentiation is presented.

Background. Patients with bilateral retinoblastoma are well recognized to have high risk of developing a second malignancy, but there are little published data regarding the outcome of these patients following treatment. Patients and Methods. We identified 15 patients with a history of bilateral retinoblastoma who received treatment at Memorial Sloan-Kettering Cancer Center for a newly diagnosed second malignancy. The median age of second tumor occurrence was 18 years (range 10-32 years). Three patients later had a third tumor (18 tumors total). Tumor sites included facial structures in 14 cases and extremities in 4. Histologies included osteosarcoma (5), leiomyosarcoma (5), high-grade spindle cell sarcoma (3), malignant fibrous histiocytoma (3), malignant mesenchymoma (1), and angiosarcoma (1). Results. Nine patients are alive: 7 disease free at a median of 29 months (range 6-214 months) and 2 with residual disease 59 and 148 months post-diagnosis of the second malignancy. Six patients have died at a median of 31 months (range 16-98 months) after diagnosis of the second malignancy. Conclusions. Patients with a history of bilateral retinoblastoma who develop a second malignancy may enjoy extended periods of survival. Aggressive therapy appropriate to the tumor histology and site is indicated.

A rare case of malignant mesenchymoma of a retroperitoneal lesion, com-posed of liposarcoma and osteosarcoma, is reported. For complete resection of the tumor, two surgical operations were performed. The first operative material showed a mass measuring 20 x 20 x 10 cm, weighing 1607g, arising from the soft tissue of the left retroperitoneum and the tumor had a smooth surface and elastic-hard consistency. The secondary operative materials exhi-bited a mass measuring 10 x 5 x 3 cm, weighing 268g. The tumor was com-posed of soft gelatinous tissues and adhered to the tail of the pancreas but was separate from the spleen. More than 3 years after the secondary operation, no recurrence has been observed. Immunohistochemical examinations showed that S-100 protein and non-specific enolase were present in the liposarcoma-tous area and that vimentin was positive in the osteosarcomatous area.

Sarcomas of the spermatic cord are rare, and malignant mesenchymomas are particularly rare. Only 8 cases of paratesticular mesenchymoma have been described previously. We report here the ninth case of malignant mesenchymoma of the spermatic cord, in which there was a local recurrence. We also briefly review the previously reported cases.

This is the first report (to our knowledge) that describes a patient with massive polyostotic fibrous dysplasia involving the calvaria and facial skeleton that subsequently underwent transformation to a malignant mesenchymoma with elements of chondrosarcoma, osteosarcoma, and rhabdomyosarcoma arising in the maxilla. Malignant transformation occurred in the absence of prior radiation exposure, osteomyelitis, or known bony infarction. A review of the literature did not reveal any similar cases of massive fibrous dysplasia of the maxilla degenerating to multiple simultaneous malignant histotypes. Arch Otolaryngol Head Neck Surg. 1997;123:106-109

This report describes the fine-needle aspiration (FNA) cytology of a case of pleuropulmonary blastoma in a 3-yr-9-mo-old male. Pleuropulmonary blastoma is considered by most authors to be distinct from pulmonary blastoma and is a rare malignant tumor of the intrathoracic cavity. FNA smears were cellular with numerous small ovoid to spindled cells with oval to elliptical nuclei exhibiting finely granular chromatin and inconspicuous nucleoli. The cytoplasm was scant and eosinophilic with indistinct borders. Focal chondroid material and blastema-like cells were noted. The differential diagnosis suggested by the cytologic findings included rhabdomysosarcoma, teratoma, neuroblastoma, malignant mesenchymoma, pleuropulmonary blastoma, and metastatic tumor. To our knowledge, this is the first report of the cytology of this tumor.

Cystic tumors of the kidney are uncommon and usually do not have solid areas. We report a predominantly cystic renal tumor with solid anaplastic component showing rhabdomyoblastic and cartilaginous differentiation in a 26-month-old girl. Terminology and pathogenesis of tumor progression are discussed along with a review of reports of tumors associated with cystic nephroma.

Malignant phyllodes tumor is usually diagnosed by the presence of benign duct-like epithelium and malignant mesenchymal tissue. In addition to the usual fibrosarcomatous features, the mesenchymal component may show areas resembling osteogenic sarcoma, chondrosarcoma, liposarcoma, leiomyosarcoma, rhabdomyosarcoma, malignant mesenchymoma, and, very rarely, malignant fibrous histiocytoma. We present one such rare case of malignant phyllodes tumor with malignant fibrous histiocytoma-like stromal differentiation.

Heterologous differentiation in metastatic leiomyosarcomas of uterine origin is an extremely rare phenomenon. We report a remarkable case of a metastatic leiomyosarcoma from the uterus with an unusual pattern of tumor progression to malignant mesenchymoma after chemotherapy. The patient, an 80-yr-old woman with a history of metastatic leiomyosarcoma of the uterus to the lungs, presented with a large intra-abdominal mass. Histologic examination of the intraperitoneal mass demonstrated a high-grade sarcoma containing various heterologous malignant mesenchymal elements including osteosarcoma, chondrosarcoma, a liposarcoma-like area, and osteoclast-like multinucleated giant cells. Only the identification of small areas of smooth muscle differentiation revealed the true nature of the tumor as a metastatic leiomyosarcoma with aberrant sarcomatous differentiation. This unique presentation emphasizes the importance of clinicopathologic correlation in the diagnosis of tumors with unusual histology.

Six cases of undifferentiated embryonal sarcoma (UES) were reviewed to determine their characteristic features on ultrasonography (US) (n = 5) and computed tomography (CT) (n = 6). US demonstrated a single large, echogenic mass with some anechoic spaces. Contrast-enhanced CT scan revealed a well-demarcated low-attenuation mass with hyperdense septations of variable shape and thickness. Discrepancy of internal architecture on US and CT was one of the important characteristics of UES. CT numbers were 25-47 HU in low-attenuation areas. Enhancing peripheral rim was found in four cases and some solid portions at the periphery or adjacent to the septa were found in all cases. Two patients who had follow-up US and CT without treatment showed enhancing solid portions, changing to hypodense as the tumor grew. When compared with the pathologic findings, US showed a more accurate representation of internal architecture than did CT. Familiarity with these US and CT findings of UES of the liver will be helpful in the differential diagnosis of primary hepatic tumors in childhood.

STUDY DESIGN This is the first report of a fibrocartilaginous mesenchymoma in the spine. SUMMARY OF BACKGROUND DATA This is a rare bone tumor composed of islands of hyaline cartilage in a collagen-producing spindle cell stroma. Seven cases of fibrocartilaginous mesenchymoma have been reported previously. Of these, four occurred in the long bones. METHODS The tumor is hypercellular with mild nuclear hyperchromasia. Few mitotic figures are present. However, it is highly infiltrative, and in the present patient, it completely encircled the spinal cord. Vertebrectomy was required to ensure tumor eradication. RESULTS Five years after tumor resection, femoral head allograft replacement of the vertebral body, and posterior spinal stabilization, there was no evidence of tumor recurrence.

Rhabdomyosarcoma is one of the most common sarcomas of childhood. It usually arises in the soft tissues but may involve bone by several different mechanisms, includ ing direct extension, metastatic spread, as a component of dedifferentiated chondrosar coma or malignant mesenchymoma, or as a primary tumor. Only nine cases of primary rhabdomyosarcoma of bone have been previously reported, many of them not well documented. The histologic, immunohistochemical, and ultrastructural findings of a primary rhabdomyosarcoma of the femur in a 68-year-old woman are presented. Also discussed are the different aspects of skeletal muscle differentiation in bone tumors and the possible explanation for the rarity of primary skeletal rhabdomyosarcoma. Int J Surg Pathol 1(4):253-260, 1994

A 50-year-old man visited our clinic with the complaint of a painless, growing swelling in the left inguinal region. High inguinal orchiectomy including tumor resection was performed. The tumor originated in the spermatic cord without invading the epididymis or the testis. Histologically, the tumor consisted of osteosarcoma, leiomyosarcoma, and liposarcoma, which was compatible with the pathological finding of malignant mesenchymoma. Postoperatively, the patient received 2 courses of adjuvant chemotherapy according to the CYVADIC regimen. He is alive 12 months after surgery with no evidence of tumor recurrence or metastasis. Malignant tumors of the spermatic cord are rare, especially malignant mesenchymoma. Our case is the 7th one so far reported in Japan.

A case of malignant mesenchymoma of the prostate is reported. Immunohistochemical and ultrastructural examination revealed malignant chondro-osteoblastic and rhabdomyoblastic features. A separate incidental prostatic adenocarcinoma was also seen. These lesions should be differentiated from carcinosarcoma in which adenocarcinoma is intermingled with malignant mesenchymal components.

We present three cases of primary bone sarcoma with rhabdomyosarcomatous component which in one case appeared in a pure form, i.e., as rhabdomyosarcoma; in the other two cases it presented as one of multiple components of the tumor. The first patient was a 70-year-old man with a tumor of the left femur involving surrounding soft tissue of the thigh. Histologically, this was a case of so-called dedifferentiated chondrosarcoma with pleomorphic rhabdomyosarcoma representing high grade malignant component. The second patient, a 31-year-old man, developed a tumor in the left tibia which was a rare, fibrosarcoma-like type of rhabdomyosarcoma. The third patient was a 43-year-old woman with a tumor in the left tenth rib which was shown to be osteo- and chondrosarcoma with a minor rhabdomyosarcomatous component and was classified as malignant mesenchymoma. All patients were treated by surgery and chemotherapy. The first two of them died of metastatic disease 3 months, and 3 years and 4 months following surgery, respectively. Light microscopical diagnosis of rhabdomyosarcoma of hematoxylin-eosin sections was confirmed immunohistochemically in each case using reactions to desmin, muscle specific actin and myoglobin, and ultrastructurally in two cases. Rhabdomyosarcomatous component in primary bone tumors appears to be rarely present but more cases may be diagnosed in the future, if immunohistochemical and ultrastructural examinations are to be employed.

Summary Undifferentiated embryonal sarcoma of the liver (UESL) is a rare primary liver tumor. Less than 100 adult cases were reported. It has female and right lobe preponderance. In pathological features, focal osteoid picture in UESL is never reported. We present a 63-year-old male patient with left lobe UESL with focal osteoid picture. He was admitted for a palpable solid mass, with left upper quadrant abdominal pain for 4 months. Abdominal computed tomography showed a huge well-circumscribed mass at left upper quadrant, 21.3 × 13 × 27.9 cm 3 in size, with multiple septa in delayed phase. En bloc resection including lateral segmentectomy, splenectomy, and cholecystectomy were performed, but tumor rupture was noted. The pathologic diagnosis was ruptured UESL. The postoperative course was uneventful, and adjuvant radiotherapy without chemotherapy was performed. Peritoneal seeding with massive ascites was noted in the 9 th month after operation. Even after receiving salvage chemotherapy, he died 1 year after operation. Early complete surgical resection with adjuvant chemotherapy may improve prognosis of UESL. But the overall survival of UESL did not improve until recently. We present this case along with a literature review of the clinical pictures, diagnosis, pathology presentation, pathologicogenesis of focal osteoid picture, treatment, and prognosis for UESL of another 23 new reported cases since 2007.

We studied 12 cases of a rare primary bone neoplasm--fibrocartilaginous mesenchymoma--including five from the original report on this condition. The seven male and five female patients were 9 to 25 years old. The metaphyses of the long bones were the most common site, with the fibula accounting for a third of all cases. Histologically, the lesion contained spindle cells, bone trabeculae, and islands of cartilage. At least some of the cartilage was in the form of plates that resembled epiphyseal plates. Intralesional excision led to a high rate of recurrence, but no metastasis or death was related to the tumor. Our results indicate that the entity described by Dahlin and co-authors is histologically distinct and that its behavior does not merit the term malignant.

A 24 year old man had a two year history of a painless mass on his right popliteal region. Magnetic resonance imaging demonstrated a 6 x 8 cm tumour mass in the lateral gastrocunemius. Histological examination of the tumour resected by radical surgery revealed that it consisted of myoblastic sarcoma and chondrosarcoma. Immunohistochemical studies were positive for Ki-67 and p53 throughout the area and for S-100 protein in the chondrosarcomatous area; in addition, they showed partial positivity for muscle common actin (HHF-35), smooth muscle actin, and myoglobin in the spindle cells. The percentages of Ki-67, p53, and p21/WAF1 positive cells in the spindle cell component were 34%, 65.7%, and < 0.1%, respectively. In addition, staining was negative for pancytokeratin, desmin, and glial fibrillary acidic protein. The SYT-SSX, TLS-CHOP, and EWS-FLI1 fusion genes were not detected using the reverse transcription polymerase chain reaction. Given the results, the definitive histological diagnosis is malignant mesenchymoma. This is the first report of malignant mesenchymoma of the lower leg with immunohistochemical and molecular studies.

Background: Spermatic cord neoplasms are a rare tumor entity and, moreover, of benign behavior. Malignant tumors of the spermatic cord are mostly of mesenchymal origin. We present the unusual case of a giant malignant mesenchymoma of the spermatic cord with bidirectional differentiation into a liposarcoma and a leiomyosarcoma. Case Report: A 84-year-old male patient presented with a scrotal mass on the left side which was observed growing since 1 year and misdiagnosed as scrotal hernia or testicular hydrocele. Ultrasound and computed tomography demonstrated a solid tumor suggesting a spermatic cord tumor. The patient underwent hemiscrotectomy, and the histological examination of the 2,500-gram specimen revealed a malignant mesenchymoma originating from the spermatic cord with two distinct histopathological compartments of liposarcoma and leiomyosarcoma. Because an adjuvant therapy protocol is of questionable effect and because of the patient’s age no further therapy was applied. The patient was closely followed and is now, 5 years after surgery, still free of disease. Conclusion: Even in older patients, scrotal masses should be considered malignant tumors as long as no benign diagnosis has been proven. Although malignant mesenchymomas are rare tumors with poor prognosis, in selected cases even large tumor masses, as presented, can be cured by surgery.

A 4-year-old bull was presented with facial distortion and abnormal respiratory noise. Endoscopically, a proliferative mass was found obliterating the left nasal cavity and a tumour was suspected. The head was examined after slaughter and there was a well-circumscribed solid structure (15×12×6 cm) extending into the paranasal sinus, the choanal region and the bones of the orbit, with focal penetration of the nasal septum. Microscopically, the mass consisted of well-differentiated trabeculae of woven and lamellar bone, areas of chondromyxomatous, immature and mature cartilaginous tissue, and regions with irregular whorled spindle cells. Tissue differentiation of the mass was variable. Centrally, there was osseous differentiation with an outermost fibromatous area resembling a zone of endochondral ossification. There was suppurative and ulcerative inflammation where the tumour extended through the hard palate and into the pharynx. A nasal malignant mesenchymoma was diagnosed on the basis of these features.

Malignant mesenchymoma of the thyroid is extremely rare. We report such a tumor involving the bilateral lobes of the thyroid which showed simultaneous chondrosarcomatous, osteosarcomatous, fibrosarcomatous and rhabdomyosarcomatous differentiation. The patient was a 52-year-old woman admitted with a history of facial swelling, neck thickness and swallowing discomfort of one month's duration. Sonographic examination indicated a thyroid mass involving the bilateral lobes. Macroscopically, the tumors of both lobes were well demarcated, solid, greyish-white, and multinodular on the cut surface. Some nodules were translucent in appearance and hard in texture. Microscopically, the tumor was composed of small primitive mesenchymal cells with osteoid formation resembling the small cell variant of osteosarcoma interspersed with multiple cartilaginous nodules that indicated chondrosarcomatous differentiation. Some tumor cells showed prominent rhabdomyoblastic differentiation with eosinophilic cytoplasm and eccentric nuclei. Fibrosarcomatous areas were also observed. Immunohistochemically, the small primitive mesenchymal cells were positive for vimentin and CD99 and negative for CD56, Syn, CgA, CK, TG, TTF-1, calcitonin, and S-100. The tumor cells in the rhabdomyosarcomatous area were MyoD1 and muscle-specific actin positive. Molecular analysis for BRAF and RAS gene alterations showed no point mutation. The tumor recurred four months after surgery and tumor thrombi were suspected in the bilateral internal carotid arteries on ultrasonography. Primary malignant mesenchymoma of the thyroid is a high-grade malignant tumor with a poor prognosis. Its differerential diagnosis includes anaplastic carcinoma and other rare sarcomas with chondroid, osteoid, and other mesenchymal metaplasia.

A 6-year-old ferret ( Mustela putorius furo) was presented with abdominal enlargement. Clinical examination revealed an intra-abdominal mass measuring approximately 5 cm in diameter. Abdominal survey radiographs revealed a sharply marginated mass with multifocal radiodense foci, suggestive of pathologic calcification. A complete blood cell count revealed a moderate, normocytic, normochromic, nonregenerative anemia. The mass was surgically removed en bloc, fixed in 10% neutral buffered formalin solution, and routinely processed for histologic and immunohistochemical investigation. The neoplastic tissue consisted of a mixed neoplastic cell population, including osteosarcoma and fibrosarcoma components. Immunohistochem-istry revealed that both neoplastic cell populations were positive for vimentin and negative for actin (smooth and striated), desmin, and myoglobin. Nonabsorbable suture material was admixed with the neoplastic tissue in the histologic section. This material was birefringent when viewed microscopically under polarized light.

Undifferentiated sarcoma is an uncommon primary malignant tumor of the liver typically occurring in older children. It is also referred to as malignant mesenchymoma, fibromyxosarcoma, or mesenchymal sarcoma. We experienced a case of undifferentiated sarcoma in 72-year-old male. Contrast enhanced liver CT scan revealed a 3.4 cm heterogeneously enhancing, ill-defined, and low attenuated mass in the left liver and subtle intrahepatic duct dilatation. And, in tubogram, there were segmental stenosis and occlusion from the hilum to the proximal common bile duct. We did ultrasonography guided liver biopsy. The pathologic finding revealed infiltrative growth of atypical cells with rhabdoid features. Some atypical cells showed clear cytoplasm, but no organoid pattern was identified. The stroma around atypical cells was filled with eosinophilic hyaline material. These tumor cells were positive for vimentin only, and the tumor was consistent with undifferentiated sarcoma of the liver.

Cardiac malignant mesenchymoma is an extremely rare malignancy with poor prognosis. We report a patient presenting with a history and clinical findings typical of mitral stenosis. Transthoracic echocardiography showed a mass on the thickened posterior mitral leaflet. Transoesophageal echocardiography revealed two tumoural masses: one on the atrial side of the posterior mitral leaflet causing mitral obstruction, the other arising in the region of the right lower pulmonary vein orifice and obstructing inflow through this vein.

A cell line (SCMC-MM-1) was established from a human abdominal tumor that was initially diagnosed as a malignant mesenchymoma by histological, immunohistochemical and clinical criteria. The cell line was composed of 2 morphologically and immunohistochemically distinct cell types, one with a small polygonal phenotype (P-type), characterized by the immunostaining of vimentin and the presence of a few electron-microscopically visible organelles, and the other with a giant tubular phenotype (T-type), characterized by the immunostaining of desmin, alpha-sarcomeric actin and skeletal-muscle myosin, and the presence of thick and thin myofilaments and Z-line materials. The parental cell line was cloned into 2 sublines, a P-type clone (SCMC-MM-1-19P) and a T-type clone (SCMC-MM-1-1T), which shared both 2q37 and 11p15 translocations, the characteristic chromosomal aberrations for rhabdomyosarcoma, with the parental SCMC-MM-1 cell line. Northern-blot analyses of the myogenic regulatory genes, including MyoD1 and myogenin, demonstrated the expression of MyoD1 in both of these sublines. Myogenin was very weakly expressed in the SCMC-MM-1-19P subline, but strongly expressed in the SCMC-MM-1-1T subline. Chromosomal and myogenic-regulatory-gene analyses revealed that both of these sublines were rhabdomyosarcoma cell lines. Furthermore, the regulatory-gene analyses indicated that these 2 sublines represented 2 distinct differentiation stages of myoblasts, and that MyoD1 and myogenin could serve as the lineage marker and the differentiation marker, respectively, of human rhabdomyosarcoma.

Malignant mesenchymoma is a tumor consisting of two or more clearly identifiable and immature mesenchymal elements. In this paper a rare experience with malignant mesenchymoma presenting as a giant tumor in the thigh is described with a review of the literature. An 83-year-old woman visited the hospital because of a giant tumor on the left thigh. A giant soft tumor with a diameter of 23 cm was confirmed. Operation was carried out and well capsulated tumor was excised with the gratiris muscle. The excised tumor was 26×23×22 cm in size and 2.6 kg in weight. Two finds of histopathological findings were shown in the tumor. One was a rhabdomyosarcoma, embryonal type. The other was a well differentiated liposarcoma sclerosing type. Therefore, the patient was diagnosed as having a malignant mesenchymoma.

Malignant mesenchymoma is a rare soft tissue neoplasm which, by definition, shows at least two distinct types of frankly malignant mesenchymal differentiation in addition to any "undifferentiated" or "fibrosarcomatous" areas. It is generally regarded as a high-grade tumor. A series of nine new cases is presented in which all patients except one were adults. Four tumors arose in the retroperitoneum, three in the thigh. The only definable constituents were rhabdomyosarcoma (eight cases), liposarcoma (seven cases), and osteo/chondrosarcoma (five cases). On histologic grounds, at least one element in each case would normally be regarded as high grade. Of six cases with a median follow-up of 4.2 years, only one has died from tumor. One further case was an incidental postmortem finding. In contrast to most current opinion, these data suggest that malignant mesenchymoma is not as aggressive as the histology would imply.

Two fatal childhood cases of the rare pulmonary blastoma are reported. One was associated with a congenital cystic adenomatoid malformation. Both neoplasms extended to involve visceral pleura and were entirely composed of blastemal and mesenchymal elements without recognizable neoplastic epithelial components. The mesenchymal component in both instances consisted of malignant rhabdomyoblasts, undifferentiated mesenchyme, and differentiated, apparently benign, cartilage. Review of the literature suggests that these features may be specific for the childhood forms of pulmonary blastoma. It is further suggested that pulmonary blastoma, malignant mesenchymoma of the lung, and primary pulmonary rhabdomyosarcoma may have a common pathogenetic origin.

We describe two cases of ossified soft tissue tumors of the retroperitoneum. Computed tomographic and magnetic resonance imaging both revealed retroperitoneal masses consisting of two components -- densely ossified and lipid-rich components. In one case, a 50-year-old man, a histological diagnosis of dedifferentiated liposarcoma with osteosarcoma was made based on the needle biopsy of the two components. In another case, a 54-year-old man, surgical resection of the complex perirenal mass was performed and the same diagnosis was made. Although an ossified component represent high-grade lesion, the fatty component is an important clue to the diagnosis of dedifferentiated liposarcoma. The imaging features may be similar to those of malignant mesenchymoma, which is not a currently used term.

We present a rare case of bilateral, recurrent and persistent pneumothorax, requiring suction drainage, as a complication of metastatic spread of a malignant neoplasm to the lungs.

Primary lung tumors are uncommon in children, and malignant mesenchymal tumors form only a small proportion of these. Leiomyosarcomas occur more commonly than rhabdomyosarcomas, whereas malignant mesenchymomas are exceedingly rare. Of the total number of primary pulmonary rhabdomyosarcomas and malignant mesenchymomas of lung reported in children, 50% have occurred in association with congenital lung cysts. The relationship between abnormal morphogenesis and neoplasia is well documented in the kidney. A similar relationship may exist in the lung between cystic parenchymal maldevelopment and embryonal mesenchymal tumors. We report a 4-year-old boy with a malignant mesenchymoma of lung arising within a congenital lung cyst; one similar case has previously been reported to our knowledge.

Dedifferentiated liposarcoma (DLPS) is one of the most frequent sarcomas of the retroperitoneum and represents most undifferentiated sarcomas of the internal trunk. In about 5% cases, the dedifferentiated component is an heterologous sarcoma such as leiomyosarcoma or rhabdomyosarcoma. We reviewed a series of 65 sarcomas with a myogenic differentiation developed in the internal trunk for which initial diagnoses were leiomyosarcoma (37), rhabdomyosarcoma (6), malignant mesenchymoma (6), and DLPS (16). Immunostainings for MDM2, CDK4, alpha smooth actin, desmin, caldesmon, myogenin, c-kit, and progesterone receptor were performed. In 48 cases, the amplification status of MDM2 and CDK4 could be evaluated with quantitative polymerase chain reaction on paraffin-embedded tissues extracted DNAs. After review of the cases, final diagnoses were leiomyosarcoma (35), rhabdomyosarcomatous (20) or leiomyosarcomatous (7) DLPS, probable DLPS (2), and malignant mesenchymoma (1). DLPS were bigger tumors (median: 18.2 cm) than leiomyosarcomas (median: 12 cm). They had a lower 5-year recurrence-free survival than leiomyosarcomas (45% vs. 71%) but a higher 5-year metastasis-free survival (73% vs. 39%). There was no significant difference in overall survival (57% vs. 34%). Outcome of patients with a DLPS with a myosarcomatous component did not differ from conventional DLPS. In conclusion, most sarcomas with a rhabdomyosarcomatous differentiation occurring in the internal trunk of adults are DLPS. Moreover, DLPS with a myogenic component have a low metastatic potential, similar to conventional DLPS and significantly lower to the metastatic potential of leiomyosarcomas.

Pancreatic tumors are primary in most of the cases. Pancreatic metastases associated with other primary malignancies, especially pancreatic metastasis of leiomyosarcoma, are uncommon. A 66-year-old woman underwent surgical resection of malignant mesenchymoma (70% osteosarcoma and 30% leiomyosarcoma) in the right thigh. In the postoperative period, a pancreatic mass was identified radiologically by abdominal computed tomography. Pylorus-preserving pancreaticoduodenectomy was performed. The surgical specimen revealed leiomyosarcoma metastasized to the pancreas. A metastatic nodule on the remnant pancreatic tail was discovered 9 mo after the first pancreatic resection, and distal pancreatectomy was performed. Cases of pancreatic metastasis from leiomyosarcoma are extremely rare, especially when the tumor was resectable. We report here a unique case of pancreatic metastasis from a leiomyosarcoma in the right thigh that had been treated surgically.

An undifferentiated embryonal sarcoma (malignant mesenchymoma) of the liver from a 5-year-old girl was found to have near-triploid and near-hexaploid clones with several chromosomal rearrangements. This is the first description of the chromosomal changes in this tumor type.

21 years after radiotherapy for breast cancer, a 63-year-old woman developed a malignant mesenchymoma of the chest wall. The total irradiation dose was 132 Gy. The first clinical symptom of this second malignancy was a slight irregular calcification around the implanted silicon protheses observed in a conventional chest X-ray. Radiation-induced sarcoma is a very rare complication of radiotherapy. In cases of chest wall calcification after radiation therapy further investigation should be carried out, because some patients with radiation-induced sarcoma could be saved, if an early diagnosis is reached.

The term malignant mesenchymoma was used to describe sarcomas containing two or more lines of differentiation. Over time, it became apparent that malignant mesenchymoma did not form a distinct clinicopathological entity and what was initially thought to represent malignant mesenchymoma could be appropriately clas-sified by other means. In this report, we detail a rare instance of combined pleomorphic liposarcoma and osteosarcoma affecting the soft tissue around the left elbow of a 64-year-old Malay man. He presented with a rapidly enlarging mass around the left elbow over 5 months, associated with increased pain and discharge. MRI revealed a soft tissue mass with a suggestion of superficial erosion of the cortical bone of the humerus. An initial biopsy was reported as a high grade sarcoma. A left shoulder disarticulation and amputation ensued. The main specimen revealed a pleomorphic liposar-coma with osteosarcoma areas, not associated with humerus bone invasion. The current understanding in dissuading the use of the term malignant mesenchymoma is discussed. The pathology of the uncommon and poorly-understood entity of pleomorphic liposar-coma is presented.

A unique case of primary myxoid liposarcoma of the thigh, in which focal pleomorphic areas were present containing rhabdomyoblasts, is described. Focal rhabdomyosarcoma in liposarcoma has only rarely been reported previously and only in dedifferentiated liposarcomas of the retroperitoneum. All but one have been recurrences with rhabdomyoblasts being absent in the primary liposarcoma. As rhabdomyoblasts were only focally present, the present case is regarded as liposarcoma with focal divergent rhabdomyoblastic differentiation rather than malignant mesenchymoma.