http://www.histopathology-india.net/SoftTissuePath.htm

It is as a rare soft tissue sarcoma showing two or more distinct types of malignant mesenchymal differentiation.

It is generally thought that malignant mesenchymomas are high grade sarcomas with a poor prognosis. However, low grade malignant mesenchymomas have been reported which had a better prognosis.

It is essential to study all areas of the tumour by means of immuno-histochemistry for an accurate histological diagnosis of malignant mesenchymoma.

Age:  Mainly adults.

Site:  These tumours are frequently located in the trunk (for example, the chest wall and retroperitoneum)and lower extremities (usually on the thigh).

Microscopic features: Consists of 3 most common components:  1.Liposarcoma ; 2.Rhabdomyosarcoma ; 3. Osteosarcoma

Myoblastic components in malignant mesenchymoma are not dedifferentiated and other distinct mesenchymal components such as regions of liposarcoma , chondrosarcoma, and osteosarcoma are neoplastic, regardless of their histological grades.

Differential diagnosis:

 Mesenchymal tumours with two or more phenotypes- i) Malignant Triton tumours ; ii)liposarcoma with smooth muscle, cartilaginous, or osseous differentiation;  iii) dedifferentiated liposarcoma and iv) dedifferentiated chondrosarcoma.

Visit: Soft tissue tumours of uncertain differentiation

Abstracts:

Recurrent pericarditis revealing a malignant mediastinal mesenchymoma.Presse Med. 2005;34(5):363-6

Osteosarcoma with rhabdomyosarcomatous component or so-called malignant mesenchymoma of bone.Pathologica. 2004;96(6):475-8.

Primary osteochondrorhabdomyosarcoma (malignant mesenchymoma) of the fibula: a rare tumour in an unusual site  case report and review of the literature.APMIS. 2004;112(9):617-23.

Malignant mesenchymoma arising from a uterine leiomyoma in the menopause.Gynecol Oncol. 2004 Dec;95(3):712-5

Malignant mesenchymoma of the lower leg.J Clin Pathol 2001; 54:877-879

Malignant mesenchymoma.Cancer. 1996 Feb 1;77(3):467-73.

Malignant mesenchymomas of soft tissue associated with numerous osteoclast-like giant cells mimicking the so-called giant cell variant of "malignant fibrous histiocytoma".Virchows Arch. 1994;424(5):539-45.

Malignant mesenchymoma. Clinicopathologic analysis of a series with evidence of low-grade behaviour.Am J Surg Pathol. 1991 Jul;15(7):607-14.

 

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