Mesenchymomas, malignant
Malignant mesenchymomas are a rare type of soft-tissue sarcoma characterized by the presence of two or more unrelated mesenchymal components. These tumors are high-grade neoplasms that can arise in various connective tissues, commonly appearing as painless swellings, particularly in the arms, legs, and retroperitoneum. The exact cause of malignant mesenchymomas is not well understood, and while there are no specific risk factors, factors related to soft-tissue sarcomas, such as exposure to certain chemicals and radiation, may play a role. Diagnosis relies on histological examination of the tumor tissue, as there are no standardized screening tests available.
Treatment primarily involves surgical removal of the tumor, potentially followed by radiation or chemotherapy, although the effectiveness of these additional treatments is still uncertain. Prognosis varies, with small tumors generally having a better outlook, while recurrence after excision is common due to the non-encapsulated nature of these tumors. Literature on outcomes is limited and sometimes conflicting, with reported survival rates showing considerable variability. Overall, malignant mesenchymomas are recognized as high-grade sarcomas with a challenging prognosis, emphasizing the need for further research in this area.
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Mesenchymomas, malignant
ALSO KNOWN AS: Mixed-cell sarcomas
RELATED CONDITIONS: Soft-tissue sarcomas
DEFINITION: Malignant mesenchymomas are a type of soft-tissue sarcoma composed of two or more unrelated mesenchymal components. These rare tumors contain at least two nonepithelial mesenchymal tissues that are high-grade neoplasms with differing histologies and are not normally associated with the same tumor. For example, one malignant mesenchymoma found in a fifty-four-year-old man's salivary gland contained undifferentiated spindle cell sarcoma, chondrosarcoma, leiomyosarcoma, osteosarcoma, and rhabdoid differentiation.
Risk factors: There are no readily identifiable risk factors particular to malignant mesenchymoma, although several risk factors associated with soft-tissue sarcomas, in general, have been identified. These include exposure to chlorophenols in wood preservatives and phenoxyacetic acid in herbicides, exposure to ionizing radiation, and very rare genetic predispositions in some families. Sporadic cases of malignant mesenchymoma in patients previously treated with radiation for breast cancer have been reported.
Etiology and the disease process: Etiology is not well understood, and connections with diet, smoking, alcohol, or preexisting conditions have not been established.
Incidence: Only about 1 percent of newly diagnosed cancers are soft-tissue sarcomas, and malignant mesenchymomas represent only a small fraction of these. These tumors can develop at any age. Reports from the literature indicate that the onset is from one and a half years to eighty-four, with a median age of forty-six years and a slight preponderance of men.
Symptoms: These tumors can arise in any of the body's connective tissues, although they are most frequently encountered in the arms, legs, hands, feet, and retroperitoneum. Unusual locations such as the neck, fibula, and uterus have also been reported. They are usually first detected as a painless swelling of the soft tissue. Retroperitoneal tumors may become quite massive before detection and may be diagnosed only after the functions of adjacent organs, such as the liver or kidneys, have been compromised.
Screening and diagnosis: No screening tests exist, although a few mesenchymomas are known to produce excessive amounts of insulin-like growth factor 2 precursor. Diagnosis is always based on direct histological examination of tumor tissue because other sarcomas of a single somatic origin can develop in the same location.
Treatment and therapy: Surgical removal of the tumor, whenever possible, is the treatment of choice. This can be followed by radiation therapy or chemotherapy (with doxorubicin), although the benefits of these postsurgical treatments are questionable.
Prognosis, prevention, and outcomes: Because this type of cancer is extremely rare, literature describing the prognosis and outcome of patients is limited and sometimes conflicting. Malignant mesenchymomas are usually described as high-grade sarcomas with a poor prognosis, although small tumors 5 centimeters or less in diameter have a much better prognosis. None of these tumors are encapsulated, so recurrence following excision is relatively common. However, in one case of a malignant salivary gland neoplasm, the cancer did not reoccur after twenty months of monitoring. Tumors positive for a rhabdomyosarcomatous are associated with poor prognosis, but the literature is limited. Some research suggests that the two-year survival rate is 75 percent, and the three-year survival rate is 37 percent. Other studies reported that zero patients remained alive two years after diagnosis.
Bibliography
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