Atypical Lipomatous Tumor/Well-Diff Liposarcoma : Differential

Comments:
The differential diagnosis of atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) includes benign lipomatous tumors/lesions as well as non-lipomatous malignant neoplasms. These entities are discussed in this and next several images.

Lipoma: The adipocytes are generally uniform in size and shape. There is little to no stroma and there are no atypical stromal cells. In contrast to ordinary lipomas, ALT/WDL show variation in the size of adipocytes and atypical stromal cells in fibrous septa.

Intramuscular Lipoma: Intramuscular lipomas frequently contain atrophic skeletal muscle fibers with hyperchromatic nuclei which may be mistaken for atypical stromal cells of ALT/WDL.