V. Special types of breast cancer 1. Paget’s disease Paget’s disease of the breast is characterized by the appearance of tumor cells in the epidermis of the nipple-areola complex. The most common clinical manifestations are nipple eczema, bleeding, ulceration and nipple pruritus. Approximately 80% of patients have an associated tumor elsewhere in the breast, and the associated tumor does not necessarily occur near the nipple-areola complex and may be either a ductal carcinoma in situ or an invasive carcinoma. For Paget’s disease without concomitant tumors, breast-conserving surgery with total NAC excision and negative margins on the underlying breast tissue is recommended, followed by whole-breast radiotherapy. Total mastectomy + surgical axillary staging may also be considered. After completion of local treatment, tamoxifen should be considered to reduce the risk of recurrence. For patients presenting with concomitant tumors elsewhere in the breast, surgery includes NAC resection ensuring negative margins, standard breast-conserving surgery to remove the peripheral tumor and obtain negative margins. It is not necessary to include NAC and peripheral tumor in the same specimen for resection or to remove them in a single incision. Total mastectomy remains the appropriate treatment option. Axillary lymph node staging is not necessary for breast-conserving surgery in patients with Paget’s disease accompanied by intraductal carcinoma and no invasive carcinoma found. For patients with invasive breast cancer found, surgical axillary staging should be performed whether they undergo total mastectomy or breast-conserving surgery. Postoperatively, systemic adjuvant therapy is administered according to the clinical stage of invasive breast cancer and estrogen and progesterone receptor status. Patients with Paget’s disease who undergo breast-conserving surgery should all undergo whole-breast radiotherapy. If lymph node metastasis of invasive breast cancer is present, the irradiation field should be expanded to regional lymph nodes. 2.Lobular breast tumors Lobular breast tumors are rare and consist of both stromal and epithelial components. Lobular tumors include benign, borderline and malignant subtypes and are rarely diagnosed correctly before excisional biopsy or mass excision. On ultrasonography and mammography, lobulated tumors often appear as fibroadenomas and cannot be reliably differentiated from fibroadenomas even by needle aspiration cytology. Therefore, clinically large, rapidly growing fibroadenomas should be considered for excisional biopsy. Lobular tumors of the breast are rapidly growing, usually painless, and the most common site of distant metastasis is the lung, either as a solid nodule or a thin-walled cavity. Local recurrence is the most common mode of recurrence of lobular tumors. Treatment of lobulated tumors is local surgical excision with negative margins ≥ 1 cm. mass excision or partial mastectomy is the preferred surgical treatment. Total mastectomy is necessary only if a negative margin cannot be obtained by mass excision or partial mastectomy. Axillary lymph node metastasis rarely occurs in lobulated tumors; therefore, surgical axillary staging or axillary lymph node dissection is not necessary unless physical examination reveals enlarged lymph nodes. For patients with local recurrence, resection of the recurrent lesion should be performed (wide negative margins are required), and then radiotherapy of the residual breast and chest wall may be considered. The role of chemotherapy and endocrine therapy in the treatment of lobulated breast tumors has not been proven. 3. Inflammatory breast cancer Inflammatory breast cancer is a rare, invasive progressive breast cancer characterized by skin engorgement and edema (orange peel-like) over more than 1/3 of the breast, with distinct palpable borders in the engorged area. In the past, inflammatory breast cancer was often classified as locally advanced breast cancer, but there is growing evidence that inflammatory breast cancer is more likely to be HER-2 overexpressed and hormone receptor negative than locally advanced breast cancer, and has a worse prognosis. Inflammatory breast cancer is treated with a combination of treatment modalities. Preoperative neoadjuvant chemotherapy is administered first, using the “anthracycline±paclitaxel” regimen. For patients with HER-2 overexpression, trastuzumab can be added to the chemotherapy regimen if economic conditions permit. After completion of neoadjuvant chemotherapy, “total mastectomy + axillary lymph node dissection” should be performed, and breast-conserving surgery is not recommended for patients with inflammatory breast cancer. Adjuvant chemotherapy should be given after surgery. For hormone receptor positive patients, postoperative chemotherapy should be followed by endocrine therapy. For patients with high HER-2 expression, it is recommended to complete 1 year of trastuzumab treatment if economic conditions permit. Finally, after completing all the above treatments, radiotherapy of chest wall and local lymph nodes is recommended. 4.Medullary carcinoma Medullary carcinoma is an uncommon variant of invasive ductal carcinoma, characterized by a highly malignant karyotype with lymphocytic infiltration and swollen tumor borders. In the past, medullary carcinoma was thought to be less likely to metastasize and to have a better prognosis than typical invasive ductal carcinoma. However, current evidence suggests that the risk of metastasis in medullary carcinoma is comparable to that of other highly malignant invasive breast cancers. Therefore, patients diagnosed with medullary carcinoma should be treated according to the treatment strategy of invasive ductal carcinoma, with comprehensive treatment according to the size, grading and lymph node status of the tumor. 5.Male breast cancer The clinical characteristics of male breast cancer are long course and late diagnosis. As there are no special symptoms in the early stage of male breast cancer, most patients fail to consult the doctor in time, and rarely associate it with breast cancer when they find a swelling in the nipple areola area, or even consult the doctor only when the lesion becomes ulcerated. Due to the small size of male breast and shorter lymphatic ducts, lymph node metastasis occurs in about 54-80% of patients at an early stage. This is one of the reasons why the prognosis of male breast cancer is worse than that of women. The principles of treatment for male breast cancer are basically the same as those for female breast cancer. Radical resection is recommended for those who are suitable for resection, and comprehensive treatment is used according to the situation; for advanced stage patients, chemotherapy, radiotherapy and endocrine therapy are the main treatments. Tamoxifen, as the conventional drug of choice for endocrine therapy in estrogen receptor-positive patients, is suitable for patients of any age. Bilateral orchiectomy is a simple, less invasive and age-independent method, and the efficiency of treatment for advanced male breast cancer can reach 50% to 60%, so it is often the treatment of choice for advanced patients.