Malignant breast tumors

The most common malignant tumor of the mammary gland is breast cancer - this is the disease with which all benign processes in the mammary gland are differentiated.

If a malignant process is suspected, ultrasound of the mammary glands allows one to evaluate the location, quantity, size, shape, echostructure, contours, additional acoustic effects, the condition of the ducts and surrounding tissues, including skin changes, as well as the presence and nature of vascularization. Most often, lesions of the mammary gland are detected in the upper outer quadrant. Up to 50% of all breast cancers are located in this quadrant. Such a frequency of lesions in this area is apparently associated with a high concentration of terminal milk ducts.

The localization of malignant tumors in other quadrants is as follows:

• lower inner quadrant - 5%;
• lower outer and upper inner quadrant - 15%;
• lower outer quadrant - 10%;
• central location behind the areola - 17%.

Breast cancer can be in the form of a diffuse form (edematous-infiltrative cancer) and a nodular form.

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Nodular form of breast cancer

It can be in the form of one or more nodes. The size of the tumor is related to the growth rate and time of their detection. Correct determination of the tumor size is important for choosing the treatment tactics. Everyone knows about the weak correlation between the clinically determined, X-ray mammographic and true, histological sizes of formations in the mammary gland. Ultrasound of the mammary glands gives a better ratio of the sizes of malignant tumors of the mammary gland compared to the data of X-ray mammography and their clinical determination. When comparing the size of the tumor with pathomorphological data, the correlation coefficient according to some data is 0.77 for palpation, 0.79 for X-ray mammography and 0.91 for ultrasound of the mammary glands. According to other data - 0.79 for clinical determination of sizes, 0.72 for X-ray mammography and 0.84 for ultrasound of the mammary glands.

During echography, the tumor is measured in three projections. In most cases, nodular forms of breast cancer are hypoechoic formations. The echo structure can be varied and depends on the presence of areas of necrosis, fibrosis, calcifications, tumor vessels. An acoustic shadow can be determined behind malignant tumors.

There is a specificity of echographic images of two morphological variants of the nodular form of breast cancer - well-demarcated tumors with an expansive growth pattern and poorly demarcated cancers (scirrhous or stellate) with an infiltrative growth pattern.

The shape and contours of these tumors are assessed according to their growth pattern.

With infiltrative growth, the tumor often has an irregular shape, unevenness of its contours is noted due to the involvement of many structures of the mammary gland in the pathological process. The contours of the tumor become even more uneven when combined with desmoplasia (secondary fibrosis) of the surrounding tissues. Desmoplasia is a response to the processes of tumor infiltration of the surrounding tissues and is characterized by an increase in the echogenicity of the surrounding fatty tissue in the form of an uneven hyperechoic rim around the tumor and other changes caused by the contraction of fibrous fibers and stroma.

With expansive (sliding) growth, tumors have a regular round or oval shape, well-defined or slightly blurred contours. The tumor pushes the surrounding tissues apart, causing their compression and deformation, but not destruction.

When pressing the sensor on a tumor with an expansive growth pattern, a slight change in its shape and a symptom of "slippage" or displacement of the formation among the surrounding tissues are observed. This is never observed when compressing solid infiltrating masses.

With echography, it is possible to differentiate the tumor's own border from fibrous reactions (desmoplasia) of surrounding tissues. With palpation and X-ray mammography, it is impossible to differentiate desmoplasia from a tumor. On X-ray images, desmoplasias look like part of a malignant tumor.

Microcalcifications are associated with breast cancers in 42% and are easily detected by X-ray mammography. The literature has widely discussed the possibilities of echography in detecting microcalcifications of the mammary glands. Using high-resolution ultrasound equipment with properly focused sensors, it is possible to detect tiny echogenic dots inside the formation, which correspond to the mammographic image of calcifications. Almost always, small calcifications do not produce an acoustic shadow. Echographically, microcalcifications are difficult to differentiate against the background of echogenic glandular tissue or tissues with a large number of reflective surfaces. X-ray mammography detects calcifications much better, therefore, the possibilities of the ultrasound method in this matter are not given much clinical significance. At the moment, the role of echography is reduced to detecting structures that include calcifications, for example, milk calcium in microcysts, intraductal calcification, calcifications inside formations.

Sensors equipped with a water nozzle allow visualization of changes in the skin of the mammary gland. Superficially located malignant tumors of the mammary gland can cause not only changes in the subcutaneous tissue, but also involve the skin structure in the process. Involvement of the skin in the tumor process can manifest itself in the form of thickening, deformation and change in the echogenicity of the skin. Less superficially located cancers can cause skin changes in the form of disruption of its normal orientation and contraction of Cooper's ligaments.

For a long time, distal weakening was considered the most constant sign of tumor malignancy. However, in the works of Kabayashi et al. (1987) it was proven that the occurrence of acoustic effects behind tumors is caused by the presence and amount of connective tissue. Acoustic shadow is determined in 30-65% of cases.

Behind a malignant breast tumor, there may be no additional acoustic effects, or there may be distal enhancement, as in medullary and mucinous cancers. Distal enhancement may also be seen behind malignant tumors growing in cystic cavities, as well as behind some infiltrative ductal carcinomas.

Ultrasound criteria do not allow differentiation of histological types of breast cancer.

Nodular forms of infiltrative breast cancer

Cancers that produce a stellate pattern, regardless of their form (infiltrative, ductal, lobular) have a scirrhous structure. Most often, in the center of such tumors, areas of fibrous, sometimes hyalinized stroma predominate. Complexes of epithelial tumor cells are located along the periphery of the tumor. Less often, a uniform distribution of parenchyma and stroma in the tumor node is noted.

The tumor borders are always unclear on echography due to the pronounced infiltration of surrounding tissues. The star-shaped form is caused by the compression of Cooper's ligaments by the tumor. One of the most common echographic signs in scirrhous forms of cancer is acoustic shadows.

It has been established that the predominance of the connective tissue component in the tumor contributes to greater attenuation of ultrasound waves, as a result of which the visualization of tissues located behind the tumor worsens. The scirrhous form of cancer is characterized by a high content of connective tissue (up to 75%).

One of the variants of invasive or infiltrating malignant process in mammary glands is infiltrative ductal carcinoma. Infiltrative ductal carcinoma can have extensive intraductal spread, which cannot always be determined during surgery and can subsequently give local relapses. From this point of view, it is very important that the border of surgical intervention passes outside the tumor infiltration. Morphological conclusion is decisive in determining tumor infiltration of ducts. X-ray mammography has good prognostic capabilities in determining the prevalence of intraductal tumors. Microcalcifications of displaceable structure, well differentiated during X-ray mammography, this process is classified as suspicious for malignancy.

Color Doppler mapping can be used to differentiate vessels from ducts, since both have the appearance of tubular hypoechoic structures.

Nodular forms of cancer with expansive growth pattern (well-demarcated)

Nodular forms of well-circumscribed cancers include medullary, mucinous, papillary, and some ductal carcinomas and sarcomas (which constitute a small percentage of breast cancers). Although these tumors compress surrounding tissue as they grow, they cause little or no fibrotic changes in surrounding tissue. Some tumors exhibit distal enhancement. Sonography cannot differentiate these well-circumscribed cancers from benign solid lesions.

Medullary and mucinous (colloid) cancers may resemble a complex of cysts with hypoechoic contents. Medullary cancers have a round or lobular shape of a cystic-solid structure, are well delimited from the surrounding tissues, and do not have a capsule. As medullary cancer grows, anechoic zones of necrosis with areas of organized and fresh hemorrhages are formed. An anechoic rim is often detected, which, according to morphological assessment, corresponds to the zone of active tumor growth. Distal enhancement is due to the predominance of the solid component of the tumor with a lower content (less than 25%) of connective tissue structures. As the tumor increases in size, a wide rim of increased echogenicity may appear anterior to the formation. With large sizes, the tumor is fixed to the anterior chest wall and may ulcerate. A small tumor clinically resembles fibroadenoma. Medullary cancers are extremely rare after menopause.

Colloid cancers are rare, slowly growing tumors, the cells of which produce mucous secretion. These tumors occur at the age of 50-60 years. In echography, their shape can be round or oval, the borders - from good differentiation to blurred. It is possible to determine calcifications. Secondary changes are not typical. Hemorrhagic changes in the internal structure are atypical.

Cavitary or intracavitary carcinoma is a rare form of malignant breast tumor. Histologically, it is a papillary cancer arising from the cyst wall. Ultrasound imaging may show a complex of cysts with thickened walls or with solid growths protruding into the cyst cavity. The second variant of the cavitary form of cancer is an image of a cyst whose wall is deformed from the outside due to infiltration from the side of the tumor growing nearby. In both cases, cysts may have echogenic contents. Cytological examination of the aspirate provides more information when it is obtained from an area containing a solid component, since the number of tumor cells in the liquid contents may be very small. The cavitary form, like solid papillary carcinoma, is more often observed in elderly women. With echography, these tumors cannot be well differentiated from their benign counterparts.

Although cancer is typically characterized by the appearance of hypoechoic lesions, ultrasound findings may be limited to simply heterogeneous architectural disturbances without an obvious mass.

Diffuse form of breast cancer (edematous-infiltrative)

The edematous-infiltrative form of cancer is a consequence of tumor cell infiltration of the lymphatic vessels of the mammary gland. Clinically, the edematous-infiltrative form is manifested by reddening and thickening of the skin, which becomes similar to a lemon peel. Echography reveals thickening of the skin, increased echogenicity of the underlying adipose tissue, and a network of hypoechoic tubular structures parallel and perpendicular to the skin (dilated and infiltrated lymphatic vessels). Other echographic changes are characterized by increased echogenicity of the parenchyma of the mammary gland with the inability to differentiate its components. Distal acoustic shadows can mask underlying formations. The edematous-infiltrative form of breast cancer does not have specific echographic or mammographic features, which does not allow differentiating it from its benign analogue - the diffuse form of mastitis.

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Other malignant processes of the mammary glands

Metastases to the mammary gland account for 1 to 6% of all malignant processes in the mammary glands. The primary tumor focus may be localized in the lungs, gastrointestinal tract, pelvic organs, urinary bladder, or contralateral mammary gland. Metastatic tumors in the mammary gland may be single, but more often multiple. They may or may not be palpable. The lesion may be unilateral or bilateral, with or without involvement of the lymph nodes. Ultrasound of the mammary glands reveals a formation of a heterogeneous structure, hypoechoic, rounded in shape with fairly smooth and clear contours. The appearance of a hyperechoic capsule (areas of desmoplasia) is atypical.

Unlike primary tumors, metastases are usually located in the subcutaneous area. Metastases may be the first manifestation of an oncological disease in a patient without a primary lesion or are found in the mammary gland at late stages of the disease. In both cases, an aspiration biopsy is necessary to establish a diagnosis, since mammographic and echographic findings are not specific. X-ray mammography reveals well-defined multiple rounded darkenings that are poorly differentiated from cysts.

Melanomas, sarcomas, lymphomas, leukemias, leukemias, myeloma disease can also cause damage to the mammary gland. There are descriptions of plasmacytoma of the mammary gland in the literature.

Sarcoma is an extremely rare lesion of the mammary glands. It most often arises from the mesenchymal elements of a benign tumor, such as phyllodes fibroadenoma, or from the stroma of the mammary gland. According to the literature, liposarcoma accounts for 0.001 to 0.03% of malignant tumors of the mammary gland. A single case of osteogenic sarcoma of the mammary gland has been described. The mammographic and echographic picture is not specific.

Dopplerography of breast diseases

Echography combined with the Doppler method can detect newly formed tumor vessels. Color Doppler mapping and power Dopplerography are considered as a promising addition to echography for differentiation of breast tissue. Color Doppler mapping around and inside many malignant tumors makes it possible to detect a much larger number of vessels compared to benign processes. According to Morishima, vascularization was detected in 90% of 50 cancers using color Doppler mapping, color signals were located on the periphery in 33.3% of cases, centrally in 17.8%, and chaotically in 48.9%. The ratio between the vascularization area and the size of the formation was less than 10% in 44.4% of cases, less than 30% in 40% of cases, and more than 30% in 11.6% of cases. The average tumor size in which color signals were detected was 1.6 cm, while no vessels were detected at tumor sizes of 1.1 cm. In the analysis of 24 breast cancers, the number of vascularization poles was taken into account, which averaged 2.1 for malignant tumors and 1.5 for benign tumors.

When attempting to differentiate between benign and malignant processes using pulsed Doppler ultrasound, the following factors must be taken into account:

• large proliferating fibroadenomas in young women are well vascularized in 40% of cases;
• small cancers, as well as some specific types of cancers of any size (such as mucoid carcinoma) may be nonvascularized;
• The detection of tumor vessels depends on the technical capabilities of the ultrasound machine to record low speeds.

The ultrasound method can detect changes in the lymph nodes in various pathological processes in the mammary glands, determine their size, shape, structure, and the presence of a hypoechoic rim. The detected round hypoechoic formations of 5 mm in diameter can be the result of inflammation, reactive hyperplasia, and metastasis. The round shape, loss of the hypoechoic rim, and decreased echogenicity of the lymph node gate image suggest its infiltration by tumor cells.

Breast ultrasound has a higher sensitivity in detecting axillary lymph nodes compared to palpation, clinical assessment, and X-ray mammography. According to Madjar, palpation yields up to 30% false negative results and the same number of false positives for lymph node involvement. Echography detected 73% of breast cancer metastases to the axillary lymph nodes, while palpation detected only 32%.

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