BI-RADS Version 2025 Mammography Updates Part 2
Part 2 review of BI-RADS Version 2025 updates for mammography for radiology board exams. Check out the study guide for this episode by clicking here.
What are key differences between nipple retraction and nipple inversion?
According to BI-RADS version 2025 nipple retraction is constant, persists on mammography even when the nipple is appropriately positioned in profile, and is suspicious for malignancy if new, unilateral, or irreversible. In contrast, nipple inversion is reversable, more often bilateral, and often shows long-term stability. Nipple retraction, as with skin retraction, can be a normal part of post-surgical scarring, so surgical history is necessary when evaluating both nipple and skin retraction.
What is the cutoff for skin thickening on mammography per BI-RADS version 2025?
Skin thickening greater than 2 mm is abnormal, unless it is in the nipple areolar complex and is symmetric bilaterally.
What type of skin thickening is most concerning for potential malignancy?
New skin thickening that is unilateral and focal is potentially concerning for malignancy in the absence of a known infectious or inflammatory process. If you see new skin thickening with underlying mass or trabecular thickening or other suspicious mammographic findings one needs to consider the possibility of inflammatory breast cancer. Mastitis can present with new unilateral focal skin thickening with underlying trabecular thickening, like inflammatory breast cancer. If mastitis does not completely resolve on appropriate treatment, one needs to consider the possibility of inflammatory breast cancer and skin punch biopsy plus biopsy of any suspicious finding(s) in the breast would be indicated.
Name other key causes of trabecular thickening.
Beyond mastitis and inflammatory breast cancer, trabecular thickening which BI-RADS version 2025 describes as thickening of the fibrous septa of the breasts can results from causes of breast edema which can include congestive heart failure and renal failure or due to impaired lymphatic drainage in the setting of axillary dissection or extensive axillary lymph node metastatic disease.
True or false? There are no well-established or validated descriptors of the extent of gynecomastia.
True, according to BI-RADS version 2025. Many describe extent as minimal, mild, moderate, or marked (or severe). But these are technically not validated or well-established at present. One can describe gynecomastia by pattern, such as nodular, dendritic, or diffuse, but BI-RADS version 2025 also states these are not currently correlated by robust data to patient outcomes.
True or false? Hormone-induced breast tissue in transfeminine patients is characterized as gynecomastia per BI-RADS version 2025.
False. According to BI-RADS version 2025 hormone-induced breast tissue in transfeminine patients should not be characterized as gynecomastia. According to BI-RADS version 2025 gynecomastia is typically the result of alterations in hormone levels due to physiologic status in adolescents or older patients.
Name common causes of gynecomastia listed in BI-RADS version 2025.
According to BI-RADS version 2025, gynecomastia can be caused by various medications including antidepressants, anti-hormonal prostate cancer medications, steroids, antibiotics, chemotherapy, certain types of cardiovascular medicines. Use of substances such as marijuana, methamphetamines, alcohol and heroin can cause gynecomastia. Systemic diseases to include hepatic dysfunction, renal impairment, lung, thyroid, adrenal, pituitary and testicular tumors or cancer, other thyroid dysfunction other than thyroid tumors, can cause gynecomastia.
True or false? Male patients with gynecomastia could potentially be reported as having dense breast tissue.
True. BI-RADS version 2025 states that breast density in a male should be determined using the same rules as for females, assigned based on the densest portion of the breast tissue, indicating the potential to obscure malignancy.
What should be included in a report of a mammogram in a patient with breast implants per BI-RADS version 2025?
The type (saline, silicone, dual lumen), location (retropectoral or prepectoral, noting retroglandular is now a historical term), description of views obtained in the technique section (often routine and implant displaced views). For silicone implants, commenting on evidence of extracapsular rupture is recommended and, if present, describing where in the breast the extracapsular silicone is located. If there has been free injection of silicone or other substances this should also be described.
True or false? If one is imaging a breast which has undergone mastectomy to evaluate a symptom on that side, standard views must still be obtained?
False. Per BI-RADS version 2025 only limited views of the area of concern need to be obtained as it can be difficult to obtain standard views in all cases, especially if the breast has not been reconstructed. A common scenario would be obtaining a mammographic view to evaluate possible but not definitive fat necrosis seen on ultrasound, as mammography can sometimes confirm the benign nature of fat necrosis therefore obviating biopsy in certain cases.
True or false? When viewing a mammogram of a breast status post mastectomy breast density should still be assigned.
True. Standard categories should be reported, which, if the breast tissue has all been removed would be almost entirely fatty, category A. If mastectomy is subtotal, the appropriate density descriptor for the residual tissue should be used.
When describing the location of a finding on a mammogram, what are required reporting elements per BI-RADS version 2025?
Laterality, followed by clock face and/or quadrant, followed by depth in the breast or distance from the nipple. If a finding is seen predominantly on tomosynthesis, the slice number should be provided for all views the finding is seen on. Bonus points if additional descriptors are included, such as the location of a finding at the fat fibroglandular junction.
True or false? When reporting distance from the nipple, the distance should be reported to precision of tenths of a centimeter (for example 2.1 cm) and the measurement is made to the posterior edge of the mass.
False for both. BI-RADS version 2025 states that centimeters from the nipple should only be reported in whole centimeters (2 cm, 3 cm, etc.) and not smaller increments as this implies a level of precision that is unrealistic. The distance measured is from the base of the nipple to the center of the mass, not the posterior margin, unless the mass is particularly large and measuring to the anterior or posterior aspect of the mass would be more helpful (if so this should be clearly described that it is measured to the anterior or posterior aspect, if not stated one would assume measurement was made to the center of the mass. Depth is reported as anterior, middle, or posterior.
True or false? More than one type of BI-RADS category 0 assessment categories exist in the new 2025 BIRADS atlas?
True.
What are the different BI-RADS category 0 assessment categories specified in the current BI-RADS atlas?
Two Category 0 assessment categories exist.
The first is Category 0: Need Additional Imaging evaluation which is used to recall a patient for additional imaging, to further evaluate a potential abnormality detected on a screening mammogram.
The second is Category 0: Incomplete: Need Prior Mammograms for Comparison.
Previously, these were combined into a single Category 0 Assessment which read “Category 0: Incomplete: need additional imaging evaluation and/or prior imaging for comparison”. To align with MQSA updates made in 2024, these are now divided into distinct categories to make it abundantly clear whether additional imaging is required or comparison with prior imaging is required.
True or False? If a highly suspicious finding is present on a screening mammogram, a BI-RADS Category 4C or 5 assessment should be assigned.
False. A Category 0 assessment should be assigned for any screening finding that needs further imaging, even if highly suspicious and almost certainly a cancer. Don’t fall into the trap on board exams of assigning a Category 4 or 5 assessment on a screening mammogram! For screening mammography, you should assign a category 0 assessment for any exam that is not Category 1 or 2. One reason why, is that even if you see the finding highly suspicious for malignancy perfectly well on the screening mammogram, you still need diagnostic imaging to determine extent of disease on mammography and ultrasound, as appropriate, prior to performing a biopsy. Thus, additional imaging is still required, and Category 0: Incomplete: Need Additional Imaging Evaluation is the appropriate assessment category. Category 3, 4, and 5 assessments are assigned after diagnostic imaging is completed, and a Category 6 assessment is assigned when malignancy is biopsy-proven and has not yet been surgically removed with definitive surgery.
Does every screening mammogram where priors from an outside facility could conceivably be retrieved but are currently not available for review at time of screening mammography interpretation require a Category 0: Incomplete: Need prior mammograms for comparison assessment?
No, per my reading of BI-RADS. The text states priors should be obtained if an examination cannot be assigned a Category 1 or 2 assessment without prior imaging, and the prior imaging can be feasibly obtained. This Category 0 category should only be used for previous imaging comparison only when such comparison is required to make a final assessment, and most typically would occur if stability of imaging findings would allow confirmation that imaging findings are benign by demonstrating long-term imaging stability.
If a Category 0: Incomplete: Need prior mammograms for comparison assessment is assigned, how long does the facility have to obtain prior imaging before the case should be signed with, or without, those prior studies?
Such an assessment should be assigned within 30 days and preferably sooner, even if prior studies never become available for comparison. This requires a reliable tracking mechanism to ensure that studies assigned this category are tracked and signed within a 30-day window. Either way, the initial report will need to be addended, and a final assessment category will need to be assigned within 30 days.
If diagnostic mammogram and/or ultrasound findings warrant further evaluation with MRI, should a Category 0: Incomplete: Need Additional Imaging Evaluation assessment be assigned?
No, typically not. The BI-RADS atlas states that rather than assigning a Category 0 assessment, the interpreting physician should issue a final assessment in a report (Category 1-5) but MRI may still be recommended for further evaluation. Additionally, Category 0 should not be assigned for mammogram or ultrasound studies that have negative imaging, when additional screening with MRI is still desired, such as in cases of increased breast density for supplemental screening or for individuals known to be at high lifetime risk of breast cancer for additional high-risk screening, or to further assess symptoms such as pathologic nipple discharge. Additionally, a category 0 assessment recommending MRI should not be given for further evaluation of findings that are already suspicious on mammography or ultrasound “as a way to potentially defer biopsy.” I’m honestly not sure why you would ever want to do that, but this is included in the new BI-RADS atlas, so this could potentially be tested on a board exam.
What is the likelihood of malignancy for a Category 1 or Category 2 assessment?
Per the BI-RADS atlas, these assessment categories have “Essentially 0% likelihood of malignancy”. Early in the new BI-RADS atlas there is a single statement that is bolded that specifies that no single or combination of imaging tests can completely exclude presence of breast cancer. The confidence in the final mammographic assessment is also to consider a patient’s breast density, meaning if there is dense breast tissue the ability of a mammogram to exclude presence of breast cancer is reduced.
What is the likelihood of malignancy for a Category 3: Probably Benign assessment?
A Category 3 assessment means the likelihood of malignancy is greater than 0 % but no higher than 2%.
What is the likelihood of malignancy for Category 4: Suspicious, overall, and then for each subcategory of Category 4 (4A, 4B, and 4C)?
Overall, a Category 4: Suspicious assessment has a greater than 2% but less than 95% likelihood of malignancy. For sub-categorization, which only exists for Category 4 versus other assessment categories, 4A: Low suspicion for malignancy has a greater than 2% but no higher than 10% likelihood of malignancy, Category 4B: Intermediate suspicion for malignancy has a greater than 10% but no greater than 50% likelihood of malignancy, and Category 4C: High suspicion for malignancy has a greater than 50% but less than 95% likelihood of malignancy.
I’ll spare a specific question on this, but Category 5: Highly Suggestive of Malignancy has a 95% or greater likelihood of malignancy. There is, of course, a Category 6 which has a 100% likelihood of malignancy as this is the assessment category used for known biopsy-proven malignancy prior to definitive surgical removal.