Possible malignant transformation of arteriovenous malformation to angiosarcoma: case report and literature review

Angiosarcoma is a rare malignant tumour, which accounts for 1–2% of all malignant soft-tissue tumours. Most cases of angiosarcoma arise spontaneously, and malignant transformation of vascular malformation to angiosarcoma is extremely rare. We describe the case of a 70-year-old woman with a massive arteriovenous malformation in her shoulder, which gradually enlarged, despite repeated surgeries and radiation therapy over 53 years. She also presented with rapidly growing haemorrhagic masses in her oral cavity. Excision biopsy was performed, and the pathohistological diagnosis was angiosarcoma. Positron emission tomography–computed tomography revealed high fluorodeoxyglucose accumulation in the oral cavity and right shoulder, the latter of which was consistent with the location of the arteriovenous malformation. The masses in the oral cavity were diagnosed as metastatic angiosarcoma from the right shoulder, where the massive arteriovenous malformation was suspected to have malignantly transformed. This report describes a possible case of malignant transformation of arteriovenous malformation to angiosarcoma.