Hemangiomas of the breast with atypical histological features. Further analysis of histological subtypes confirming their benign character.

Eighteen patients with vascular tumors of the breast that exhibited characteristics raising the question of but not qualifying for a diagnosis of low-grade angiosarcoma were reviewed. We had previously referred to these lesions as "atypical" hemangiomas because of concern regarding the diagnosis and the risk of the later development of angiosarcoma. Significant features, variably present, included small size (less than 2.0 cm), relative circumscription, broadly anastomosing vascular channels, and endothelial hyperplasia. Destructive invasion, solid areas, and hemorrhage or necrosis unrelated to a needle localization procedure were absent. Four distinct histological patterns were observed: cavernous, compact capillary, capillary budding, and a combined cavernous and compact capillary type. The age of the patients varied from 19 to 82 years (mean 60 years). Eleven tumors were detected mammographically. The size of the lesion ranged from 0.4 to 2.0 (mean 0.9) cm. The diagnostic biopsy was the only treatment in nine (50%) cases. Reexcision was performed in seven and mastectomy was done in two cases. Follow-up ranged from 1 to 140 (mean 44) months. There have been no local or systemic recurrences. Hemangiomas with diverse histological patterns have been detected clinically with the increasingly widespread use of mammography. Further follow-up indicates that the lesions originally referred to as "atypical" are benign and not associated with an appreciable risk of the development of angiosarcoma. Complete excision alone is recommended to treat these tumors, which may be diagnosed as hemangiomas and subclassified according to growth pattern.