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WHO Classification of Tumours
Leiomyosarcoma, NOS
Connective, subcutaneous and other soft tissues


Definition

Leiomyosarcoma is an uncommon, aggressive malignant smooth muscle neoplasm, histologically characterized by a proliferation of neoplastic spindle cells. Morphologic variants include epithelioid leiomyosarcoma , myxoid leiomyosarcoma , granular cell and inflammatory leiomyosarcoma
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Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
3rd Edition
IARC Press: Lyon 2002



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Soft tissue leiomyosarcoma arises in intramuscular and subcutaneous locations. The most commonly affected site is the retroperitoneum, including the pelvis. Another distinctive subset of leiomyosarcomas arise in large blood vessels. Nonretroperitoneal leiomyosarcomas most frequently develop in the lower extremities. The tumours typically form fleshy masses. Larger lesions may contain areas of haemorrhage, necrosis, or cystic change. Tumour size depends on the location; retroperitoneal leiomyosarcomas are usually large (>10 cm) and may extend into adjacent organs, while nonretroperitoneal lesions tend to be smaller

Click for details
Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
3rd Edition
IARC Press: Lyon 2002



.
Soft-tissue leiomyosarcoma most commonly affects middle-aged or older persons. Retroperitoneal and inferior vena cava leiomyosarcomas show a distinct predilection for women, while tumours in other soft tissue sites affect both men and women in approximately equal proportion. The prognosis depends chiefly on tumour location and size; additional reliable prognostic factors are histological grading and osseous/vascular involvement. Retroperitoneal leiomyosarcomas are fatal in the great majority of cases. Leiomyosarcomas of large vessels also tend to have a poor prognosis, while nonretroperitoneal soft tissue leiomyosarcomas are generally more favourable in outlook

Click for details
Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
3rd Edition
IARC Press: Lyon 2002



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