Angiomatoid fibrous histiocytoma, abbreviated AFH, is a rarely metastasizing tumour that affects children and young adults.
Angiomatoid fibrous histiocytoma Wikipedia
It is characterized cystic blood-filled spaces and composed of histiocyte-like cells. A lymphocytic cuff is common. It often simulates a vascular lesion, and was initially described as doing this.
AFH typically has a chromosomal translocation involving the ATF1 gene -- t(12;16) FUS/ATF1 or t(12;22) EWS/ATF1.