BI-RADS breast density
The BI-RADS classification identifies 4 types of breast tissue density: from type 1 (predominantly fatty tissue) to type 4 (extremely dense glandular tissue). These parameters have direct prognostic significance.
Women with type 4 density require special attention, as their risk of developing cancer is 4–6 times higher compared to patients with type 1 density. Future screening programs are planned to transition to individual risk stratification. Such a system will combine mammographic density, family and reproductive history, and blood tests for single nucleotide polymorphisms.
For high-risk patients, the use of additional imaging modalities is discussed. These include whole-breast ultrasound, magnetic resonance imaging (MRI), tomosynthesis, and contrast-enhanced mammography. However, to date, the question of their mandatory routine utility remains debatable.
Simple cysts (Cysts)
A cyst is the most common cause of an isolated mass in the breast. They most frequently occur in women aged 20–50 (with a pronounced peak at 40–50), and are often multiple and bilateral. It is important to remember that cysts are not associated with an increased risk of malignancy.
- Mammography: visualized as sharply circumscribed round or oval structures. Sometimes a radiolucent rim (lucent halo) is defined along the contour.
- Ultrasound criteria: the diagnosis is established when three features are present. These are well-defined margins (round/oval shape), complete anechogenicity (confirming fluid content), and posterior acoustic enhancement (posterior enhancement) — a bright zone behind the cyst resulting from good sound wave transmission through fluid.
Fine-needle aspiration of the contents is performed only if the cyst causes symptoms or if there are diagnostic doubts. Routine submission of fluid for cytology is unnecessary — it is done only when bloody aspirate is obtained or if the ultrasound picture is atypical.
Fibroadenomas (Fibroadenomas)
This is the most common cause of benign solid (tissue) masses in the breast. The peak incidence occurs in the third decade of life. On palpation, a fibroadenoma feels like a smooth, mobile, and well-circumscribed nodule.
- Mammography: the shadow has a round or oval shape with clear borders. In elderly patients, coarse calcifications may develop within the lesion.
- Ultrasound criteria: oval or lobulated shape, presence of a thin echogenic pseudocapsule. Regarding echogenicity, they are most often isoechoic or moderately hypoechoic, less frequently hyperechoic compared to surrounding fat.
If the patient is under 30 years old and the presentation is classic, percutaneous biopsy can be avoided (cancer risk approaches zero). At an older age, a biopsy is mandatory for differential diagnosis with well-circumscribed carcinomas.
Phyllodes tumor (Phyllodes tumour) This lesion visually mimics a fibroadenoma. The danger is that up to 25% of such tumors are locally aggressive and can metastasize. Treatment consists of surgical excision with clear resection margins. To avoid missing a phyllodes tumor, large (>3 cm) and rapidly growing fibroadenomas are also always surgically removed.
Intraductal papilloma (Papilloma)
Papillomas are benign proliferations developing within the ducts. They can be located both in the center of the breast and on its periphery.
Clinically, papillomas often present with nipple discharge. The tissue of this lesion is very fragile (friable), so it is easily traumatized and bleeds, secreting watery or bloody fluid.
Briefly: answers to topical questions
What types of breast density are identified by the BI-RADS classification?
The BI-RADS classification identifies 4 types of breast density.
- Type 1 — predominantly fatty tissue.
- Type 4 — extremely dense tissue.
About 10% of women have type 1 density, and 10% have type 4. Patients with extremely dense tissue have a 4–6 times higher risk of developing breast cancer compared to women with predominantly fatty tissue. Characteristics of intermediate types are not described in available data.
Which ultrasound features indicate malignancy of a solid breast mass?
Specific ultrasound features indicate malignancy of a breast neoplasm.
- Indistinct margins (ill-defined masses) — the boundaries of the lesion are poorly differentiated.
- Marked hypoechogenicity (markedly hypoechoic) — decreased echogenicity compared to the surrounding adipose tissue.
- Vertical orientation (taller than wide) — the anteroposterior dimension of the lesion exceeds its transverse diameter.
- Echogenic halo (echogenic halo) — presence of an ill-defined border around the lesion, especially along the lateral margins.
An additional criterion for a malignant process is the deformation of adjacent tissues.
To remember the three classic ultrasound criteria for a simple cyst, use the rule: Well-defined margin, Anechogenicity, Posterior enhancement.
Class and exam questions
Is it always necessary to perform puncture and cytology of a breast cyst?
No. Fine-needle aspiration is indicated only for pain relief or in case of diagnostic doubts. Cytological examination is not performed routinely, with the exception of blood admixture in the aspirate or atypical ultrasound features.
How to distinguish a phyllodes tumor from a fibroadenoma?
Clinically and instrumentally, they look almost identical. Suspicion of a phyllodes tumor arises with rapid growth of the nodule or its size exceeding 3 cm — in such cases, prophylactic surgical excision is indicated.
Is a biopsy mandatory when a fibroadenoma is detected?
For young women (under 30) with a typical ultrasound picture, a biopsy is not mandatory. In patients older than this age, percutaneous biopsy is necessary to rule out a well-circumscribed carcinoma.
What else to study on this topic
- Contrast-enhanced mammography: pros and cons
- Genetic markers in risk stratification (single nucleotide polymorphisms)
- Morphology and histology of phyllodes tumors
- Differential diagnosis algorithm for nipple discharge
- Atypical ultrasound features of cystic lesions
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