What are the different types of liposarcomas, and how do they differ?
Liposarcoma is one of the more common subsets of soft tissues sarcomas and tends to be a heterogeneous group of tumors. Starting off again from a spectrum perspective of fatty tumors, lipomas are typically the benign tumors. These don’t transform or degenerate into a malignancy a lipoma tends remains a lipoma. But, within the malignant spectrum of these fatty tumors are the lipomatous tumors. You have a low grade or grade 1 variant called atypical lipomatous tumor, which used to be called a differentiated liposarcoma. This by itself does not have any metastatic potential, but over a period of time can undergo dedifferentiation or transformation into a higher grade tumor.
The intermediate grade tumor would be a mixoid liposarcoma. These can be more aggressive with a higher proportion of what is called "round cell component." Then there are the high-grade liposarcomas, which would include pleomorphic liposarcomas and the dedifferentiated liposarcomas, where the well differentiated liposarcoma transformed into a higher grade spindle cell sarcoma, thus rendering the clinical diagnosis of a dedifferentiated liposarcoma.
It's not unusual that when we get questions about a patient with a liposarcoma, we would have to first start off by asking if they can please clarify what type of liposarcoma we are talking about, because the biology and clinical behavior are different and metastatic patterns can be different. Certainly, there may also be some therapeutic significance in each one of these subsets that would be quite relevant for a given patient.
CASE: Soft-Tissue Sarcoma Case 2
Michael C is a 59-year-old social worker from Los Angeles California; his medical history is notable for obesity, COPD, and mild hypertension.
In September of 2014, Michael returns for follow up and his CT scan shows a 4 cm posterior mediastinal mass, and a 6 cm perinephric mass suspicious for metastatic disease. He initiates treatment with anthracycline and ifosfamide chemotherapy (6 cycles) for recurrent disease and shows a partial response.