dedifferentiated liposarcoma

dedifferentiated liposarcoma

A poorly-differentiated pleomorphic sarcoma which accounts for 10% of liposarcomas. It is a mixture of well-differentiated liposarcoma and a high-grade non-lipogenic sarcoma, an aggressive component. About 50% of retroperitoneal liposarcomas are dedifferentiated. 75% occur in the retroperitoneum; other sites include the extremities and paratesticular region. Dedifferentiated areas can be that of:
(1) High-grade pleomorphic sarcoma, which mimics what was once called pleomorphic malignant fibrous histiocytoma or fibrosarcoma, or
(2) Low-grade sarcoma, mimicking well-differentiated fibrosarcoma, low-grade myxofibrosarcoma or fibromatosis. Divergent differentiation occurs in 1/4 of cases and includes rhabdomyosarcomatous, leiomyosarcomatous, osteo-chondrosarcomatous or angiosarcomatous areas.

Clinical findings
Legs (e.g., popliteal fossa and medial thigh), retroperitoneal, perirenal, mesenteric region, shoulder.

Prognosis
Despite their high-grade appearance, DDLs tend to be less aggressive than other types of high-grade pleomorphic sarcomas: local recurrence in 40%, metastases in 10%. Location is the single most important prognostic factor; retroperitoneal DDLs fare far worse than those located on the extremities.

DiffDx
Any high-grade or pleomorphic sarcoma should be considered, as well as metastatic poorly-differentiated carcinoma, melanoma, or lymphoma.

Genetics
Ring or giant-marker chromosomes due to an amplification of chromosome 12q13-15, which results in the amplification of one or more genes in the region, including HMGA2, MDM2, SAS, GLI, CHOP, CDK4.
References in periodicals archive ?
MDM2 and CDK4 immuno-stainings are useful adjuncts in diagnosing well-differentiated and dedifferentiated liposarcoma subtypes: a comparative analysis of 559 soft tissue neoplasms with genetic data.
Pathological and radiological differential diagnosis Small round blue cell tumour Radiological Non-Hodgkin's lymphoma Rhabdomyosarcoma Rhabdomyosarcoma Myosarcoma Small cell lung cancer Malignant fibrous Merkel cell cancer histiocytoma (MFH) Haemangiopericytoma Dedifferentiated liposarcoma Neuroblastoma Ewing's sarcoma Ewing's sarcoma Primitive neuro-ectodermal tumour (PNET)
Histological examination revealed a dedifferentiated liposarcoma of the cord with tumour-free margins of resection and no lymphovascular invasion.
MDM2 and CDK4 immunostainings are useful adjuncts in diagnosing well-differentiated and dedifferentiated liposarcoma subtypes: a comparative analysis of 559 soft tissue neoplasms with genetic data.
Histopathology of the resected mass revealed a dedifferentiated liposarcoma.
Histopathologic examination revealed a dedifferentiated liposarcoma.
Final histology confirmed that the patient had a dedifferentiated liposarcoma.
Dedifferentiated liposarcomas have the appearance of well-differentiated liposarcomas except for areas of dedifferentiation with a nonlipoblastic sarcomatous component.
Dedifferentiated liposarcoma is a bimorphic sarcoma with both well-differentiated liposarcoma components and a second nonadipose sarcoma.
Although less specific in this setting, MDM2 FISH was also used to provide support for the diagnosis of dedifferentiated liposarcoma when the well-differentiated component was not easily identifiable; this was possible because dedifferentiated liposarcomas maintain the molecular signature of MDM2 amplification found in the well-differentiated liposarcomas from which they arise.
Liposarcoma with meningothelial-like whorls: a study of 17 cases of a distinctive histological pattern associated with dedifferentiated liposarcoma.
The high-grade tumors, which contain very minimal or no gross fat, but rather a very cellular appearance, are the pleomorphic, round cell, and dedifferentiated liposarcomas.