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Composite sarcoma of bone is a very rare entity that primarily affects adolescent and young adult patients. It usually combines areas of liposarcoma and osteosarcoma, and up to 60% of cases have metastatic disease at diagnosis. It is a highly aggressive pathology with intrinsic resistance to bone sarcoma conventional treatments. The prognosis is poor, with long-term survival rates not exceeding 30%. We present the case of an adolescent female diagnosed with an aggressive composite sarcoma of bone with rhabdomyosarcoma foci and loco-regional lymph node involvement.

A male castrated Golden Retriever was presented for evaluation of a large mass over the left shoulder extending to the lower part of the neck that had been present for an extended period of time, but had a recent history of rapid growth. Previous aspirates of the mass were consistent with a lipoma. The mass was surgically excised and was diagnosed as an extraskeletal osteosarcoma based on histopathology. After surgery, the dog was initiated on a chemotherapy protocol with carboplatin and metronomic cyclophosphamide. He became neutropenic, anemic, and thrombocytopenic 14 days after the carboplatin treatment was administered. The neutropenia resolved, but the anemia and thrombocytopenia progressed. A bone marrow aspirate revealed erythroid hypoplasia, myeloid hyperplasia with a predominance of early precursors, and a subset of cells that made up 20% of the total population that were reported as bizarre and unclassifiable. These cells were discrete in nature and were thought to be hematopoietic in origin. The dog was euthanized due to deterioration of the clinical condition. On postmortem examination, widespread metastasis involving the lungs, liver, kidney, heart, and bone marrow was found. Histopathology of the tumor lesions determined 2 distinct malignant populations of liposarcoma and osteosarcoma, consistent with malignant mesenchymoma. However, the possibility of 2 separate neoplastic processes cannot be definitively excluded. This is the first report of bone marrow metastasis of a malignant mesenchymoma in a dog.

A rare case is reported of malignant mesenchymoma of a retroperitoneal lesion involving the kidney and composed of leiomyosarcoma and liposarcoma. The tumor, measuring 13 x 12 x 11 cm and weighing 1910 g, arising from the soft tissue of the retroperitoneum or renal capsule, was completely removed surgically. Thirteen months after surgical operation, multiple metastasis was observed. Immunohistochemical and electron microscopical examination showed two different mesenchymal elements. Magnetic resonance imaging findings were compatible with the pathological findings. This case appears to be the second in the world literature.

A 12-year-old German shepherd crossbreed dog was presented with a submandibular mass that was initially diagnosed as myxosarcoma on incisional biopsy. Chest radiographs were taken for staging, and magnetic resonance imaging was performed to assess the feasibility of cytoreductive surgery before adjuvant radiotherapy. The dog underwent debulking surgery, and histology permitted reclassification of the tumour as a malignant mesenchymoma (with myxosarcomatous and osteosarcomatous differentiation). The dog was subsequently treated with four fractions of radiotherapy given at seven-day intervals and three doses of carboplatin. The dog remained stable following therapy until its condition acutely deteriorated, and it was euthanased 153 days after surgery. On postmortem examination, there were no signs of local tumour recurrence, but metastases were observed both in the thorax and in the abdomen.

Malignant mesenchymoma, defined by Stout as sarcomas comprising two or more unrelated differentiated tissue elements other than a fibrosarcoma component, is rare. We report a case of primary malignant mesenchymoma of the proximal fibula in a 10-year-old female student who presented with pain and swelling of the right knee for 2 months. Initial biopsy showed features of rhabdomyosarcoma only, but the resected specimen revealed additional osteosarcomatous and chondrosarcomatous elements. The patient remained well more than 5 years after initial presentation. Including our present patient, 16 cases of primary malignant mesenchymoma of bone are found in the English literature, affecting mainly adolescents and young adults, with a slight male predominance and predilection for the metaphysis of long bones, especially around the knee. More than 60% of the patients develop metastasis, almost invariably to the lung, but occasionally to the brain. About 60% of the patients, all with metastasis, died mostly within one year of diagnosis. The clinical features of primary malignant mesenchymoma of bone thus resemble those of conventional osteosarcoma. Moreover, our case illustrates that, with combination chemotherapy targeted for individual elements, the prognosis of this rare tumour might be much improved, as in osteosarcoma.

Malignant mesenchymoma of the uterus, arising in a leiomyoma Aims: To document and find evidence for the rare occurrence of malignant progression of a benign uterine leiomyoma with divergent mesenchymal differentiation. In a 54-year-old female a large pedunculated tumour was encountered which had suddenly increased in size and had apparently arisen at the site of a subserosal uterine leiomyoma first described 19 years earlier. The tumour seemed histologically diverse in its composition. The possibility of malignant progression of the benign leiomyoma with divergent mesenchymal differentiation was entertained. Methods and results: In the resected tumour, smooth muscle, osseous and adipose components were identified and these were assessed using recognized histological criteria of malignancy. In addition to a benign smooth muscle component, malignant leiomyosarcomatous tissue was seen in addition to a malignant osseous component and a malignant adipose component. The tumour thus met the criteria of a malignant mesenchymoma. The relationship of the different components of the tumour was analysed by immunohistochemistry and with molecular loss of heterozygosity (LOH) analysis. In the osseous and leiomyosarcomatous components a similar LOH pattern was observed. The adipose component showed a distinct LOH pattern. Retention of smooth muscle differentiation in the osseous component was demonstrated by desmin immunostaining. Conclusion: Malignant transformation of benign uterine leiomyoma may rarely occur. Mesenchymal stem cells underlying these tumours may show divergent mesenchymal differentiation.

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.

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.

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.

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 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.

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.

A case of a rare primary cardiac tumor in a 46-year-old woman is described. The tumor arose from the left atrium and was histologically composed of multiple mesenchymal elements of fibrosarcoma, rhabdomyosarcoma, chondrosarcoma, myosarcoma, and liposarcoma. Metastasis of this tumor occurred in the left femur, lung, and hilar lymph nodes after the second heart operation. Histogenesis of malignant mesenchymoma was considered with a survey of the literature.

The clinical and pathologic findings of two patients with malignant ectomesenchymomas of soft tissue are reported. Malignant ectomesenchymomas are a composite of ganglion cells or neuroblasts and one or more malignant mesenchymal elements, usually rhabdomyosarcoma. Our first case was composed of ganglioneurosarcoma plus rhabdomyosarcoma, the second composed of neuroblastoma plus rhabdomyosarcoma. The name is derived from the suggestion that they arise from pluripotential ectomesenchyme. An English language literature search revealed 11 other cases that arose in soft tissue and had adequate clinicopathologic data. Of the 13 cases, 10 occurred in infants, three occurred in adults, and nine were males. Six patients were alive and free of disease at last follow-up (range, 0.6-12 years; mean, 3.4 years), four patients had died of tumor (within 0.5-3.3 years; mean, 1.3 years), one case had died of Adriamycin (doxorubicin) toxicity, and two cases had been lost to follow-up. Complete surgical resection is the mainstay of treatment and chemotherapy appears to be important.

The first case of a primary, cystic sarcoma of the kidney, containing fibrohistiocytic, osteoid, and cartilaginous elements (malignant mesenchymoma) is reported. The neoplasm occurred in a 29-year-old white woman, who had a right upper quadrant mass at least four years prior to presentation. Light and electron microscopy findings are presented. A 14-month follow-up revealed an extensive tumor recurrence in the right perirenal area with no apparent metastastic disease.

Although sarcoma occurring in the true retroperitoneum is not uncommon, sarcoma in the retrorectal space is unique. We report a patient with a malignant mesenchymoma, a rare soft tissue tumor, in the retrorectal space. Complete resection was accomplished through a combined Kraske's posterior and midline anterior approach. The rectum had not been invaded by the mass. Survival of patients with malignant mesenchymoma does not exceed 50% in most reports, and the role of adjuvant chemotherapy or radiation has yet to be defined. Its attendant morbidity must be weighed against an uncertain prognosis.

Sixteen patients are presented who had sarcomas of the chest wall at a site where a prior malignancy had been irradiated. The first malignancies included breast cancer (ten cases), Hodgkin's disease (four cases), and others (two cases). Radiation doses varied from 4200 to 5500 R (mean, 4900 R). The latency period ranged from 5 to 28 years (mean, 13 years). The histologic types of the radiation-induced sarcomas were as follows: malignant fibrous histiocytoma, nine cases; osteosarcoma, six cases; and malignant mesenchymoma, one case. The only long-term survivor is alive and well 12 years after resection of a clavicular chondroblastic osteosarcoma. Three cases were recently diagnosed. Despite aggressive multimodality treatment, the remaining 13 patients have all died from their sarcomas (mean survival, 13.5 months). All patients have apparently been cured of their first malignancies. Chemotherapy was ineffective. No treatment, including forequarter amputation, appeared to palliate the patients with supraclavicular soft tissue sarcomas. Major chest wall resection offered good palliation for seven of eight patients with sarcomas arising in the sternum or lateral chest wall. Close follow-up is needed to detect signs of these sarcomas in the ever-increasing number of patients receiving therapeutic irradiation.

A case of malignant mesenchymoma of the bladder, containing fibroleiomyomatous, myxomatous, osteoid, and cartilaginous components is presented. The primary pedunculated tumor measuring 18 X 10 X 9 cm and weighing 934 g, arose from the anterior wall of the bladder and was treated by partial cystectomy. Six months after surgery, cystoscopy revealed a recurrent tumor situated at the dome of the bladder. The patient received surgery, chemotherapy, and irradiation for recurrent tumor, but died of the disease 21 months after the first operation. Autopsy revealed extensive local recurrence with wide-spread metastases of malignant mesenchymoma of the bladder and an incidental finding of coexisting clear cell carcinoma in the right kidney (pTl, NO, MO). There have been no previous reports of association of malignant mesenchymoma of the urinary bladder and renal cell carcinoma.

A case of ganglioneuroblastoma associated with malignant mesenchymoma is reported. The tumor originated from the retroperitoneum and was comprised not only of neuroblastoma and ganglioneuroma, but also of typical rhabdomyosarcoma, liposarcoma, undifferentiated mesenchymoma, as well as cartilaginous tissue. No distinct border existed between these different components. The histogenesis of the tumor is discussed. We suggest that the tumor derived from a remnant of neural crest (ectomesenchyme). CUM^ 36:1050-1056, 1975.

After inoculating newborn W/Fu rats with adenovirus type 9, 27 of 27 females developed mammary fibroadenomas with a latency period of 14-25 weeks. No tumors were observed after inoculation with adenovirus type 5 or in males with the type 9 inoculation. After persistence of the tumors for 3-14 months, malignant transformation of the stroma resulted in different types of sarcoma in three rats: fibrosarcoma, round-cell liposarcoma, osteosarcoma and malignant mesenchymoma. In another animal the stroma of a fibroadenoma was highly cellular, suggesting a transition into fibrosarcoma. Malignant transformation of the epithelial component was not observed. Tumor cells contained adenovirus type 9-specific T-antigen, and rats with transplanted tumors were immunized to T-antigen. Mammary fibroadenomas without signs of malignant transformation developed in eight of nine female rats inoculated with adenovirus type 9 at an adult age. Neonatal thymectomy and total body x-irradiation neither significantly shortened the induction time of adenovirus 9-induced fibroadenomas nor increased the frequency of malignant transformation in females. One lipoma and one highly differentiated liposarcoma, however, appeared in two male rats. The results provide an example of the progression of a virus-induced benign tumor into a malignant neoplasm.

A malignant tumor from the thigh of a 65-year-old man was examined by light and electron microscopy. The tumor was diagnosed by light microscopy as malignant mesenchymoma with prevalence of leiomyosarcomatous or liposarcomatous components, but electron microscopic study revealed that the basic cell was similar to chondroblastic or osteoblastic cells. However, a precise ultrastructural classification of the tumor cells was not possible, since the majority of the cells had mixed features. The histogenesis, differentiation, and relation to prognosis are discussed.

Between 1972 and 1980, 58 children with malignant tumors underwent iridium 192 (192Ir) curietherapy at the Institut Gustave Roussy. Data from only 45 of them were reviewed (bilateral retinoblastoma and salvage procedures were excluded). The pathologic diagnosis was rhabdomyosarcoma in 75% of cases, yolk sac tumor in 13% of cases, malignant mesenchymoma in two cases, clear cell carcinoma in two cases, and undifferentiated sarcoma in one case. The two major sites were pelvis-perineum (64.5%) and head and neck (31%). The treatment was essentially based on a combination of chemotherapy, which was adapted to the histologic type of the tumor, and curietherapy. Partial surgery was carried out in certain cases, either before chemotherapy for diagnostic purposes, or after chemotherapy to remove infiltrative residual tumor. External beam radiotherapy was used in a few cases in lymph node irradiation. The radioactive material was 192Ir, using afterloading techniques, either intracavitary or interstitially or both. The tumor dose, calculated by computerized dosimetry, was 60 to 65 Gy delivered over 5 to 7 days in the majority of cases. Two patients were lost to follow-up. Thirty-five patients (78%) are alive with no evidence of disease after a mean follow-up period of 5 years. Eight patients died, one of complications related to chemotherapy and seven of the evolution of their disease. The late-complication rate, studied in 33 patients with a minimum follow-up period of 3 years, is 18% (6/33). Curietherapy seems to be a preferable conservative treatment in children with localized and accessible malignant tumors.

Moloney murine sarcoma virus (M-MSV) was injected directly into the fetuses of Sprague-Dawley rats during the late stage of gestation and into the neonates within 24 hours after birth. Ninety rats developed 188 neoplastic lesions during the 8-week period of observation. Nearly all of the neoplasms were of mesenchymal derivation. Sixty percent of these neoplasms revealed more complex histologic features than those previously reported for neoplasms induced in rodents with M-MSV and were designated "malignant mesenchymoma" which developed preferentially in the proximal parts of the extremities, distant from the inoculation site. Rhabdomyosarcoma and osteosarcoma which developed in a pure form at the various sites were the next most common tumor type. Osteosarcoma developing in a pure form and as a component of malignant mesenchymoma in the humerus and femur was comparable to that of juxtacortical osteosarcoma of man; The development of excessive bones were observed in the forelimb and/or hind leg, suggesting a type of skeletal malformation. The reaction to M-MSV merits attention as a model for the study of an osteosarcoma and malignant mesenchymoma as well as rhabdomyosarcoma and also for the study of viral teratogenesis in man, as "rubella syndrome".

This paper reports a sarcoma of the chest wall following postoperative radiation therapy for breast carcinoma. A total of 9346 rads was delivered at a 2-cm tissue depth from two treatment courses separated by a five-year interval. The sarcoma appeared 16 years following the initial radiation course. The existence of two mesenchymal elements in the lesion led to the final diagnosis of malignant mesenchymoma. Criteria for evaluating a possible radiation-induced malignancy are discussed.