Lobular tumors of the breast are fibroepithelial tumors that can be classified as benign, junctional or malignant according to their histological characteristics.
Etiology
The etiology of this disease is still unknown. In addition to race, age and geographical factors, it may also be related to hygiene practices, childbirth and breastfeeding, and endocrine changes. Lobular tumors of the breast may occur initially or may evolve from fibroadenomas, as in a few cases the presence of a prior fibroadenoma adjacent to the lobular tumor has been demonstrated, or may even be a fibroadenoma in the first place.
Clinical features
Incidence: Lobular tumor is an uncommon tumor among breast lumps, accounting for 0.3-0.5% of female breast lumps.
Age of onset: The majority of lobular tumors are located at the age of 35 to 55 years, with an average age of 40 years, and it is diagnosed at an average age 10 years or more older than fibroadenoma.
3. Site of onset: About 2/3 of lobular tumors occur in the right breast, most of which are located in the upper outer quadrant.
Clinical manifestations: The main manifestation is a painless, single mass that can be palpated, occasionally accompanied by pain, the average size of the mass is 4-5 cm, more than 60% of patients have >10 cm. Many patients have a continuously growing mass, while some patients have a stable mass for a long time, but the mass increases rapidly within a short period of time. Adolescent women may present with bloody nipple discharge due to spontaneous infarction of the tumor. Large tumors >10 cm may cause skin tightness with superficial varicose veins, but ulcers are rare and nipple retraction is rare. The masses usually do not invade the pectoral muscle and skin and have good mobility. Lobular tumor axillary lymph node metastasis is rare, less than 5%.
5.High frequency ultrasonography of breast: non-invasive and can be used as the first choice. Its ultrasound presentation is a hyperechoic mass with envelope, which may also contain scattered cystic areas. The specific signs of ultrasonography can help in preoperative diagnosis and are important for the selection of treatment plan. However, ultrasonography cannot distinguish benign, junctional and malignant lobulated tumors.
6.High frequency X-ray of breast
It shows a round, round-like or lobulated solid high-density mass with clear edges, uniform density and increased hematopoiesis, and a few with microcalcifications. The mass is usually large, and a hypodense halo is seen due to swelling and compression of the surrounding interstitial mammary gland. When the mass is small, it is difficult to distinguish from a fibroadenoma. Some of the masses may have poorly defined borders, but there are no signs of malignancy such as disorganization of the surrounding glandular structures, distortion, or thickening of the adjacent skin, and even in lesions located behind the areola, the subcutaneous fat space is still clearly visible and does not cause nipple areola retraction or invagination. Calcifications within the mass are uncommon and are mostly coarse benign calcifications, and the axillary lymph nodes are usually not significantly enlarged. Currently, most scholars believe that there is no significant relationship between the benignity and malignancy of lobulated breast tumors and the size of the mass, the degree of lobulation and the presence or absence of calcification. In conclusion, if a middle-aged woman presents with a large lobulated mass with clear border and rapid short-term enlargement, and if the mass is round or lobulated with high-density shadow, surrounded by halo signs and increased blood corona, but without obvious malignant signs, the possibility of lobulated tumor should be considered.
7.MRI
In T1-weighted tumor, the tumor density is lower than or equal to normal tissue, while in T2-weighted tumor shadow is larger than normal tissue. The irregular cyst wall and low diffuse signal correspond to hemorrhagic infarction and necrosis in the tissue and high proliferation of stromal cells, respectively. Some physicians report that the use of contrast-enhanced MRI increases the sensitivity of differentiating between benign and malignant tumors. In the temporal signal profile, a signal enhancement within 1 min is more likely to be a malignant lobulated sarcoma. The value of MRI in the diagnosis of lobulated breast tumors remains to be studied.
8.Pathology
Fine needle aspiration is difficult to distinguish lobulated tumors from fibroadenomas due to the small amount of tissue, and has a high rate of false negatives and false positives (>30%), so multi-point needle aspiration combined with immunohistochemical analysis is recommended. Even so, many clinicians still consider the results of FNA unreliable, with a compliance rate of only 50.6% with the final clinical paraffin results.
Although the confirmation rate of frozen pathological examination is higher, reaching 77.8%, which is significantly higher than that of imaging and cytological examination, it is more difficult to distinguish lobulated tumors from fibroadenomas in intraoperative frozen sections, and malignant lobulated tumor components may be misdiagnosed as undifferentiated carcinoma, thus leading to unnecessary overtreatment, so the diagnostic significance of frozen sections is not significant.
Some scholars reported that the positive prediction rate of hollow-core needle biopsy for lobular tumor diagnosis is 83%, which is significantly higher than that of intraoperative frozen pathological examination and helps to improve the preoperative diagnosis rate. Therefore, for clinical suspicion of lobulated tumors, hollow-core needle aspiration biopsy should be preferred, and surgery should be decided according to the diagnosis, and there is no need to perform resection surgery for frozen pathology examination, which can effectively reduce the chance of reoperation and overtreatment.
Diagnosis
Preoperative diagnosis is difficult and often misdiagnosed as fibroadenoma, and pathological examination is required to confirm the diagnosis. The biological behavior is difficult to guess, such as a large lump, or a sudden growth of an existing lump, or recurrence after mastectomy for fibroadenoma, especially multiple recurrences should be considered; effective methods for breast cancer diagnosis are also used for lobulated breast tumors, including fine needle aspiration (FNA), hollow needle biopsy (CNB), ultrasound, mammography and breast MRI. Among them, clinical physical examination, imaging examination and fine needle aspiration cytology examination have no definite significance, while hollow needle aspiration is the most valuable examination method for preoperative diagnosis of lobular breast tumor.
Treatment
Lobular tumors of the breast are potentially malignant tumors and are treated differently from fibroadenomas. Surgical margins are the best prognostic indicator for local recurrence of lobulated tumors.
1.Surgical treatment: Breast lobular tumor is mainly treated by surgery. There is no correlation between the recurrence and metastasis of tumor and the choice of surgical methods such as enlarged mastectomy or mastectomy to preserve the breast, while the main reason of tumor recurrence is that the cut margin is not negative at the first surgical resection.
If the tumor is relatively small and can have enough cutting edge, extended excision of the tumor is the preferred surgical method for lobulated breast tumor, and the scope of surgical excision should include normal breast tissue beyond 1~2cm from the breast tumor; if intraoperative freezing indicates positive cutting edge, it can be excised again. Due to the different treatment methods and clinical prognosis, it is required to make a clear diagnosis before surgery so that appropriate surgical treatment can be carried out, which can effectively avoid incomplete excision or over-treatment.
2. Simple mass excision: If the mass is excised immediately (no margin) or the margin is only a few millimeters, nearly 1/5 will recur, and this proportion is higher in junctional and malignant lobular tumors and lower in benign lobular tumors. If the benign lobular tumor is difficult to be removed or deformed, the strategy of “wait and see” can be considered.
If benign lesions recur after local excision or repeatedly recur, they should be treated as malignant.
4.After the recurrence of lobular tumor, a wide range of re-excision must be performed, and sometimes total mastectomy is needed.
2.Other treatments
Radiation therapy and systemic therapy have not been proven but must be considered. Initial treatment of primary lobulated tumors does not require radiotherapy, but adjuvant chest wall radiotherapy should also be performed after secondary surgical resection for patients with local recurrence after lumpectomy or mastectomy, because secondary or tertiary local recurrence of more invasive lesions may be devastating.
The efficacy of the use of systemic adjuvant therapy is unknown. When systemic adjuvant therapy is used for metastatic lobulated tumors, the principles of treatment for sarcoma should be followed rather than those for breast tumors.
Follow-up
Breast examination and imaging should be performed twice a year for 5 years after lobectomy and once a year after 5 years. The imaging examination is usually done by ultrasound, which can easily detect the recurrence of tumor in the location of tumor remnants. If the breast gland is dense and rich, and the mass may not be found by ultrasound, breast MR examination is needed. MR examination should be performed within 1 year after surgery, and if the mass grows faster or is suspected to be malignant, the interval between MR examination and surgery should be shortened even more.