Adenoidcysticcarcinoma, which used to be called “cylindroma”, is one of the most common malignant tumors of the salivary gland. Adenoid cystic carcinoma can be divided into adenoid/tubular type, which is better differentiated, and solid type, which is less differentiated, according to its histological pattern. Adenoid cystic carcinoma is most commonly found in the minor salivary glands of the palate and parotid gland, followed by the submandibular gland, and tumors occurring in the sublingual gland are mostly adenoid cystic carcinoma. Adenoid cystic carcinoma should be treated accordingly according to its clinicopathological characteristics: 1. Tumors tend to spread along the nerves, so they often have neurological symptoms, such as pain, facial paralysis, tongue numbness or paralysis of the sublingual nerve. The palatal tumor may spread to the skull base along the palatal nerve, therefore, the pterygopalatine duct should be removed together with the tumor during surgery. Submandibular gland tumor may spread along the lingual nerve, and the lingual nerve should also be retrospectively removed during surgery. After maxillary tumor resection, if there is obvious pain in the maxillofacial area, it often indicates tumor recurrence. 2. The tumor is extremely infiltrative and has no boundary with the surrounding tissues. Tissues that appear normal to the naked eye are commonly infiltrated by tumor cells under the microscope, and sometimes it can even be jumpy. It is difficult to determine the normal perimeter during surgery. In addition to expanding the normal perimeter during surgery design, it is advisable to make frozensection during surgery to determine whether the perimeter is normal. 3. The tumor is easy to invade blood vessels and cause hematogenous metastasis, and the metastasis rate is as high as 40%, which is one of the highest metastasis rates among oral and maxillofacial malignant tumors. The most common site of metastasis is lung. Metastasis can occur when the patient is seen, but mostly after surgical resection of the primary site. Metastasis can occur in the presence of recurrence of the primary site or in the absence of recurrence of the primary site. Metastases may appear early or late, and the latest may be 3 to 5 years after treatment of the primary site, or even longer. In cases of pulmonarymetastasis, unless the pleura is invaded and pleural fluid appears, there are usually no obvious conscious symptoms. Therefore, chest radiographs should be routinely and regularly performed to determine the presence of lung metastasis. Chemotherapy can be used after surgery to prevent hematogenous metastasis. 4. The rate of cervical lymph node metastasis is very low, or the tumor directly invades the surrounding lymph nodes instead of the tumor embolus entering the lymphatic vessels causing the real metastasis. Therefore, selective cervical lymph node dissection is generally not necessary. However, adenoid cystic carcinoma located at the root of tongue has a high rate of metastasis, so selective cervical lymph node dissection can be considered. 5.Tumor cells infiltrate along the bone marrow cavity, often as scattered tumor cell clusters, and when decalcification is not obvious, there is often no obvious bone destruction on the X-ray. Therefore, it is not possible to judge whether the jaw bone is invaded by tumor or not based on the presence or absence of bone destruction. 6. Radiation therapy alone cannot achieve radical cure, but together with postoperative radiation therapy can significantly reduce the recurrence rate after surgery and improve the survival rate of patients (survialrate). Adenoid cystic carcinoma is often not easy to be cleaned by surgery, and there are often residual tumor cells. Therefore, postoperative radiotherapy is often required. 7. Except for solid type, adenoid cystic carcinoma generally grows slowly and the metastases in the lung also progress slowly, so the patient can live with tumor for a long time. Therefore, even if pulmonary metastases appear, if the primary foci can be eradicated, surgical treatment of the primary foci can still be considered.