Re-discussion of unexplained metastatic carcinoma of the neck (I) Recently, five cases of metastatic carcinoma of the neck were admitted consecutively, and the primary foci were not detected by all examinations (whole-body examination, including PETCT). Onset of disease: 1~9 months. Early stage was asymptomatic and presented as painless lumps; there was local pressure after growth and local pain in 2 cases over 8 cm. Two cases were referred to our hospital after a period of ineffective treatment for cervical lymphatic tuberculosis in local hospitals and accelerated growth of the masses. Characteristics of the swelling (metastatic lymph node characteristics): irregular, often larger than 1.5 cm, the largest 8 cm; hard texture, no pressure pain; often several fused, indistinct margins; poor mobility, adhesion with the surrounding. In late stages, they may break down and form skin ulcers. The characteristics of general inflammatory lymph nodes are: mostly oval, often less than 2 cm, soft, no pressure pain, good mobility, and clear borders. Examination: head (including sinus, orbit), thyroid, nasopharynx, oropharynx, larynx, hypopharynx, esophagus, chest (lung, mediastinum), stomach, abdomen (liver, spleen, kidney, gallbladder, pancreas), etc. No primary site was seen including PetCT examination. Diagnosis : (1). Fine needle aspiration biopsy confirmed the diagnosis in 2 cases; (2) Partial or complete lymph nodes were excised for pathology to confirm the diagnosis in 3 cases. Pathological diagnosis: metastatic squamous cell carcinoma. Treatment: 3 cases underwent neck debulking, and the other 2 cases could not be resected because the tumor involved the common carotid artery. Chemotherapy was done in all cases. Comprehensive treatment: continued radiotherapy + herbal medicine according to the situation. Significance of metastatic cancer in the neck: Regional lymph nodes play a certain filtering and barrier role for cancer cell dissemination or metastasis, but some experiments have shown that this role is minimal. Once metastasis is indicated, the primary cancer is more malignant and can metastasize through lymph and blood. (To be continued)