PIK3CA and cancer: Activating mutations of PIK3CA and inactivating mutations in PTEN are frequently found in human cancers.[17,18] Metabolic and epigenetic aberrations of the MAPK pathway are also prominently associated with carcinogenesis.[19] TP53, a crucial tumor suppressor, is the most frequently mutated gene (>50%) in human cancers.[20] However, the expression of these key cancer-related genes in the scalp and facial angiosarcoma is not clear.