What type of tumor originates from fat and features a complex echogenic pattern with thick walls?

Liposarcoma is a malignant tumor that arises from adipose (fat) tissue and is characterized by its complex echogenic patterns observed on ultrasound. The tumor typically presents as a mass with thick, irregular walls, which can be identified due to its fatty composition interspersed with fibrous tissue. This echogenic pattern is often seen due to variations in tissue densities—less dense fat areas contrasted with denser fibrous components within the tumor.

Understanding the histology of liposarcoma is essential, as it varies in its cellular differentiation and can encompass several subtypes, each with distinct ultrasound characteristics. The presence of thick walls and heterogeneous echogenicity are important indicators radiologists look for when diagnosing such tumors.

While other tumor types on the list arise from different tissues and can present with their own echogenic patterns, they would not typically originate from fat like liposarcoma does. This distinct origin and the way it appears on imaging make liposarcoma the correct answer to this question.