Atlas of breast cancer early detection

On its own, the shape of a lesion is not specific to its type, however along with other ultrasound features, its description adds to the diagnostic information. The shape of a mass can be described as round, oval, or irregular.

Round
A round mass is a circumscribed lesion of round shape. It is important to describe the echotexture of a round lesion to differentiate between probably benign or malignant and to assess where the lesion lies in the spectrum of benign round lesions. Ultrasound is the most useful modality for further assessment of the echogenicity of a round mass as solid or cystic or complex cystic and solid. The margins of a round mass further characterize the mass. A round lesion with circumscribed margins is more likely to be benign, whereas a round lesion with indistinct margins is more likely to be malignant .

Oval
An oval lesion is an elliptical lesion that is wider than tall and may have 2–3 lobulations. Evaluation is similar to that for round lesions. It is important to assess the margins and echotexture of an oval lesion to categorize the mass as probably benign or malignant .

Irregular
An irregular shape suggests a greater chance of the lesion being malignant. However, irregular shape can also be seen as a result of infection, abscess, inflammation, or breast trauma. Surgical scarring and biopsy can also lead to irregular margins .