Angiosarcoma of skin, light micrograph. Angiosarcoma is a rare, highly aggressive tumour that makes up less than 1% of all sarcomas. They show variable degrees of blood vessel formation and range from well-differentiated tumours resembling haemangiomas to highly anaplastic solid tumour that may be mistaken for poorly-differentiated carcinomas or sarcomas. The most common location is skin (scalp, face, forehead, and neck), followed by parenchymal organs (breast, heart, liver, spleen, and bone) and deep soft tissues. The peak incidence is seen in the 7th decade. The image shows angiosarcoma that arose in the scalp of an elderly male. It is moderately-differentiated and consists of anastomosing network of vascular channels.