Pleomorphic Lipoma

Comments:
Vascularity is not prominent in most cases of spindle cell/pleomorphic lipomas and consists of a few thick-walled vessels; however, some cases show plexiform vasculature or hemangiopericytoma-like staghorn vessels.

Another unusual pattern noted in some spindle cell/pleomorphic lipomas is the so-called pseudoangiomatous pattern (shown here). It consists of irregular branching spaces with villiform connective tissue projections lined by endothelial-like cells. Subsequent immunohistochemical studies have shown them to be positive for endothelial markers (hence true angiomatous pattern).