For Physicians. By Physicians.™

ObGFirst: Get guideline notifications, fast. First month free!Click here

BI-RADS: Standardizing Breast Imaging and Reporting 


BI-RADS: Breast Imaging Reporting and Data System, was developed by the American College of Radiology (ACR) to standardize mammogram reporting, as well as breast ultrasound and MRI reporting.

The standard mammogram report includes the following

  • Indication and type of mammogram (screening/diagnostic)
  • Statement regarding breast density
  • Description of pertinent findings including size and location, oriented by quadrant and clock position
  • Summary of important findings and BI-RADS category


BI-RADS Classification Standardizes Findings and Recommendations for Further Management

BI-RADS 0 : Incomplete

  • Recall for additional imaging/comparison with prior examinations, or both

BI-RADS 1: Negative  (Essentially 0% chance of malignancy)

  • Routine screening

BI-RADS 2: Benign (Essentially 0% likelihood of malignancy)

  • Routine screening

BI-RADS 3: Probably benign (> 0% but ≤ 2% likelihood of malignancy)

  • 6 month follow-up or continued surveillance

BI-RADS 4: Suspicious (> 2% but < 95% likelihood of malignancy)

  • 4A: Low suspicion for malignancy (> 2% to ≤ 10% likelihood)
  • 4B: Moderate suspicion for malignancy (> 10% to ≤ 50% likelihood)
  • 4C: High suspicion for malignancy (> 50% to < 95% likelihood)
  • Tissue diagnosis needed for all BI-RADS 4  categories

BI-RADS 5: Highly suggestive of malignancy (95% likelihood of malignancy)

  • Tissue diagnosis needed

BI-RADS 6: Known, biopsy proven malignancy

  • Surgical excision when appropriate

Density Categories

  • Category a: Breasts are almost entirely fatty
    • Prevalence: 10% of the population
    • Mammography considered highly sensitive in this setting (88%)
  • Category b: There are scattered areas of fibroglandular density
    • Prevalence: 43% of the population
    • Still sensitive but decreased from category a (82%)
  • Category c: Breasts are heterogeneously dense
    • Prevalence: 39%
    • Small masses may be obscured
    • Sensitivity drops to 69%
    • Note: Breast cancer risk is 1.2 relative risk compared to average breast density
  • Category d: Breasts are extremely dense
    • Breasts are extremely dense
    • Significantly lowers sensitivity of mammography (62%)
    • Note: Breast cancer risk is 2.1 relative risk compared to average breast density

Learn More – Primary Sources:

ACOG Practice Bulletin No 164. Diagnosis and Management of Benign Breast Disorders 

ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System

ACOG Committee Opinion 625: Management of with Dense Breasts Diagnosed with Mammography


Atypical Hyperplasia of the Breast: Follow-up and Management


Atypical hyperplasia of the breast is a benign but high-risk condition that can be either ductal (ADH) or lobular (ALH); these occur with equal frequency and together are found in about 10% of breast biopsies. Either entity confers a long-term risk of breast cancer that approaches 30% at 25 years of follow-up.

  • Surgically excise atypical hyperplasia when found on a core-needle biopsy
    • Necessary to avoid missing invasive cancer due to sampling error
    • DCIS or invasive cancer found in 10 to 20% of cases
  • Exception: Clinical and radiologic follow-up appropriate when atypical hyperplasia is an incidental finding at the site of a targeted biopsy
  • Current breast cancer risk assessment models perform poorly among women with atypical hyperplasia
    • Atypical hyperplasia associated with a relative risk of approximately 4 for future breast cancer
  • Follow-up screening recommendations include annual mammography, breast awareness, and  clinical encounter every 6 to 12 months
    • Also consider
      • Tomosynthesis
      • Annual MRI to begin at diagnosis
    • Based on emerging evidence, ACOG also recommends consideration of yearly breast MRI for atypical hyperplasia
  • Encourage pharmacologic risk reduction with either a selective estrogen-receptor modulator (SERM) or an aromatase inhibitor (AI) for prevention of breast cancer
  • Counsel about healthy lifestyle including ideal body weight and alcohol reduction
  • Atypical hyperplasia is generally not an indication for surgical risk-reduction / mastectomy


Atypical hyperplasia of the breast reflects proliferation of dysplastic epithelial cell populations.  It is felt to be a transitional zone between benign and malignant breast disease, containing some but not all features of a cancer. Although statistically the long-term risk of breast cancer equals or exceeds that conferred by family history and other risk factors, current guidelines in screening do not reflect this.  Similarly, pharmacologic risk reduction strategies have been adopted by <1% of women who could potentially benefit from them.


  • Atypical lobular hyperplasia is histologically similar to lobular carcinoma in situ, but less extensive
  • Atypical ductal hyperplasia and ductal carcinoma in situ share histologic features
  • Both types of hyperplasia share molecular characteristics and gene expression, indicating possibly a continuum of abnormalities

Learn More – Primary Sources:

Atypical Hyperplasia of the Breast—Risk Assessment and Management Options

Understanding the premalignant potential of atypical hyperplasia through its natural history: a longitudinal cohort study

National Comprehensive Cancer Network. Breast cancer screening and diagnosis.

ACOG: Diagnosis and Management of Benign Breast Disorders

Office Evaluation of Breast Disorders


While multiple disciplines are required to diagnose and manage both benign breast disorders and breast cancer, the most important interaction with a patient remains the initial office visit

  • Obtain careful history of all breast related symptoms including duration, changes in symptoms over time, presence and color of nipple discharge
  • Identify risk factors for breast cancer, including
    • Advanced age (over 65)
    • Positive family history
    • Age >30 at first birth
    • Nulliparity
    • Never breastfed
    • Menopausal hormone therapy
    • Alcohol use (not clear what the threshold is)
  • Visually inspect and manually palpate the breasts, axillae and supraclavicular nodal regions
  • Clinical documentation of any mass should include size, consistency, distance from areola and clock position in the breast
  • Diagnostic imaging includes ultrasonography, mammogram or digital tomosynthesis
    • Manage breast lesion based on age, clinical suspicion, Breast Imaging Reporting and Data System (BI-RADS) and other imaging findings
    • Ultrasound can differentiate solid from cystic lesions
  • Histology can be obtained from fine needle aspiration (FNA), core needle biopsy or excisional biopsy, procedures that are usually performed by radiologists or surgeons
  • Women ≥30 years and older with palpable mass
    • Mammogram followed by ultrasound, if necessary
  • Women under 30 years with a palpable mass: Ultrasound is the primary imaging modality
    • If ultrasound imaging is suspicious for cancer, follow up with tissue biopsy
    • If ultrasound does not suggest malignancy but clinical suspicion remains, perform a diagnostic mammogram
    • If ultrasound imaging suggests a benign cyst or a benign appearing solid mass options are to follow-up with physical exam +/- ultrasound/diagnostic mammogram every 6-12 months for 1-2 years to assess stability
  • Women presenting due to a mass that cannot be palpated by patient or clinician should not be dismissed and must be followed up with imaging


Benign breast lesions can be categorized as nonproliferative (breast cysts), proliferative without atypia (fibroadenoma, intraductal papilloma, fibrocystic change) which may carry a small risk (1.5 to 2 times above general population) for breast cancer and atypical hyperplasia (ductal or lobular). The latter category carries a substantially increased risk of subsequent invasive cancer in either breast (see ‘Related ObG Topics’, below). Nipple discharge is common, and usually benign. Unilateral, uniductal and spontaneous discharge carries a higher risk of malignancy and should be further evaluated with ultrasound.


  • Women ≥30 years with palpable breast masses shown to be solid on imaging should be biopsied if BI-RADS 4-5, or if BI-RADS 1-3 with high clinical suspicion
    • Observation an option if BI-RADS 1-3 and low clinical suspicion (see ‘Related ObG Topics’ below)
  • Women with simple cysts can undergo routine follow-up
    • Consideration for biopsy should be given to complicated cysts with BI-RADS 1-3
    • Complex cysts with BI-RADS 4-5 on imaging require biopsy
  • When common skin problems are identified in the breast such as psoriasis, eczema, contact dermatitis, Candida infections, standard treatment should be used
  • Skin edema, warmth and erythema as well as ulceration, nipple retraction/crusting/scaling should raise concerns for malignancy and require tissue diagnosis

Learn More – Primary Sources:

ACOG Practice Bulletin No 164: Diagnosis and Management of Benign Breast Disorders

ACS: Breast Cancer Prevention and Early Detection