A pictorial review of the imaging findings of BI-RADS 3 category are described. The main mammographic and sonographic features as well as some specifc conditions in which the category may be used are specified. 

There are three suitable findings for BIRADS 3 category in mammography:

• Non calcified, round or oval mass with at least 75% circumscribed margins (Fig. 01a). This lesion was not identified as benign or suspect in complementary studies, it has a stability less than 3 years and can be palpable. 
• Grouped round or punctate calcifications (Fig. 01b). Grouped calcifications are defined as at least 5 calcifications in 2 cm and are characterized as round or punctate after magnification. 
• Focal asymmetry without associated calcifications or architectural distortion (Fig. 02). It should be identified in two views, present with convex margins and maintain the same morphology besides occupying less than one quadrant. Futhermore, it should not be identified as benign or suspect in complementary studies. 

   

Sonographic findings categorized as BI-RADS 3:

• Hypoechoic, circumscribed, oval and parallel mass (Fig. 03). It can be palpable and mostly are fibroadenoma. In case of multiple bilateral circumscribed nodules, category BI-RADS 2 can be used.
• Isolated complicated cyst (Fig. 04). Thin-walled cystic lesion which contains debris (manifested as homogeneous echoes) and does not have a solid component.
• Clustered microcysts (Fig. 05). This imaging finding is defined as a group of anechoic cysts, each one smaller than 2 or 3 millimeters, interspersed with thin septa (less than 0,5 millimeters) without solid components. 

The BIRADS 3 can also be used in findings different from those above based on the radiologist experience.

Mammography

• Asymmetry or distortion that may result from surgery.
• Calcifications suggestive of onset of steatonecrosis (Fig. 06).
• Calcifications that may be vascular (Fig. 07).
• Emergence of calcifications potentially from the same process as other benign (Fig. 8).

Ultrasound:

• Refraction shadowing without an associated mass (Fig 09a).
• Hyperechoic mass with central hypoechoic components or other lesion suggestive of steatonecrosis. (Fig. 09b and 10).
• Architectural distortion possibly due to postsurgical scar.

In some cases, the imaging findings may be misclassified or present with size or morphology changes (Fig. 11). Futher, a complementary study can help elucidating the nature of the imaging finding (Fig. 12).