8811/3 Fibromyxosarcoma


Connective, subcutaneous and other soft tissues
ICD-O-3 topography code: C49
ICD10: C49

Myxofibrosarcoma comprises a spectrum of slow-growing malignant fibroblastic neoplasms. Most tumours arise in the limbs/limb girdles. Approximately two-thirds of cases develop in dermal/subcutaneous tissues, the remainder in the underlying fascia and skeletal muscle. Superficial lesions typically consist of multiple nodules, whereas deep seated lesions often form a single mass with an infiltrative margin. The tumours are histologically characterized by a prominent myxoid matrix composed of hyaluronic acid, curvilinear, thin-walled blood vessels, and incomplete fibrous septa. Low grade tumours are hypocellular and contain only few, non-cohesive, plump spindled or stellate tumour cells. In contrast, high grade tumours contain sheets and fascicles of spindled and pleomorphic tumour cells and areas of haemorrhage and necrosis.
Myxofibrosarcoma is one of the most common sarcomas in the elderly (most patients are in the 6th-8th decades of life) and shows a slight male predominance. Irrespective of tumour grade, local recurrence occurs in up to 50-60% of cases. In contrast, metastases and tumour associated mortality are closely related to histological grade. Metastases develop mainly in lungs and bones, but also in lymph nodes. The overall 5-year survival rate is 60-70% 1
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