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 ?
Dedifferentiated liposarcoma with rhabdomyoblastic differentiation in an 8-year-old girl.
Dedifferentiated liposarcoma of the lower extremity with low-grade dedifferentiation and low-grade osteosarcomatous component.
We describe an unusual case of rapidly growing foot dedifferentiated liposarcoma of foot which is rare.
Classification of liposarcoma has been described according to histological features, which establishes four subtypes: lipoma-like, myxoid differentiation, pleomorphic, and dedifferentiated liposarcoma.
Furthermore, as part of an additional analysis, patients with liposarcoma in Study 309 were categorized by three subtypes, dedifferentiated liposarcoma, myxoid/round liposarcoma and pleomorphic liposarcoma, and additional analyses were carried out on each subtype.
In Study 309 patients with liposarcoma were categorized into three subtypes, dedifferentiated liposarcoma, myxoid/round liposarcoma and pleomorphic liposarcoma, and additional analyses were carried out on each subtype.
Dedifferentiated liposarcoma of the small bowel mesentery presenting as a submucosal mass.
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)
6) Furthermore, dedifferentiated liposarcoma may exhibit heterologous differentiation in about 5-10% of cases, which apparently does not affect the clinical outcome.
Dedifferentiated liposarcoma of retroperitoneum and mesentery: varied growth patterns and histological grades-a clinicopathologic study of 32 cases.