Squamous cell carcinoma of the breast is a primary squamous cell carcinoma of the breast, a rare clinical type of metaplastic carcinoma of the breast. Squamous cell carcinoma of the breast is relatively rare and occurs in middle-aged women, accounting for 0.5%-2% of all breast cancers, and is mainly seen between the ages of 35-80 years, with an average age of 50-58 years. It mostly takes breast lump as the first symptom, and the lump is usually large, fast-growing, solid, and may have cystic changes, and generally has no characteristic difference with ordinary breast cancer, and some patients may be accompanied by inflammation of the breast such as skin redness, swelling, ulceration, and pain. Microscopically, squamous cell carcinoma of the breast has the general histologic features of squamous carcinoma, which is irregular and nest-like. According to the different differentiation degree of tumor cells, they can be divided into highly differentiated type and undifferentiated type. In highly differentiated type, intercellular bridges and keratinized beads are obvious. Undifferentiated type may have prismatic cells, obvious heterogeneous cells, easy to see nuclear schizophrenia and pathological nuclear schizophrenia. The rate of axillary lymph node metastasis is lower than that of invasive ductal carcinoma of the breast, which is only 10-30%, but the rate of distant metastasis is higher, which is about 30%. Squamous carcinoma of the breast is a rare disease in clinic, with an incidence of about 5 per 1000.