Most commonly caused by blunt or surgical trauma, although hematomas may develop in patients who are anticoagulated or have clotting abnormalities. The combination of hemorrhage and edema more commonly results in an ill-defined mass or a diffuse area of increased density. Although the mammographic findings simulate carcinoma, a history of trauma suggests a conservative approach. Follow-up examinations show gradual decrease in size or even disappearance of the lesion. An organized hematoma may occasionally persist as a more sharply defined mass.
Imaging Findings:Medium to high-density mass, often having slightly irregular margins. Overlying skin edema is usually present in the acute stage if the hematoma is secondary to trauma.
Hematoma. (A) Mammogram of a firm, palpable mass that arose at a recent biopsy site shows a dense lesion associated with skin thickening (arrows). (B) Three months later, there has been almost complete resolution of the hematoma with only minimal residual architectural distortion (arrows).
ILL-DEFINED HEMATOMAOverlying skin thickening from edema and bruising may simulate carcinoma. Hematomas tend to resolve within 3 to 4 weeks.
Imaging Findings:May appear as an ill-defined lesion (more commonly a relatively well-defined mass or a diffuse increase in density).
Hematoma. Ill-defined area of increased density (arrows) in the area of a lumpectomy performed 2 weeks previously.