Primary angiosarcoma of the breast is an extremely rare tumour with a difficult diagnosis and poor prognosis. We report a case of primary breast angiosarcoma diagnosed in the pathology department of the University Hospital of Oujda. An analysis of the epidemiological, diagnostic and therapeutic aspects of this type of tumour is made in this manuscript. Mastectomy is the standard treatment; the place of radiotherapy and chemotherapy is not well established. We report a case of a 18- year-old woman having an infectious symptomatology of the right breast for which she received an anti-infectious therapy inducing regression of inflammatory symptoms presented with a quick growing mass. Initial core needle biopsy showed a malignant vascular proliferation. The patient underwent a mastectomy. The tumor histology showed papillary formations and vascular structures lined by atypical cells with hyperchromatic nucleus and eosinophilic cytoplasm. The tumor cells expressed CD34 and CD31 but were negative for cytokeratin. The diagnosis of angiosarcoma grade I was made. The patient is now receiving chemotherapy. She is still alive.