Intravascular angiomatosis.

For 55 years much has been written about a peculiar benign intravascular process which can be misdiagnosed as angiosarcoma unless careful attention is paid by the pathologist to its benign cellular morphology and growth pattern. The cases reported in the literature demonstrate an increased incidence in the extremities and the head and neck, with a propensity for the subcutaneous tissues of the perioral region. Four cases are presented to further point out the perioral incidence and emphasize the differential diagnostic criteria for benignancy, including intravascular proliferation without atypical mitotic activity and necrosis in areas devoid of vascular differentiation.