Adenocarcinoma accounts for about 20% of all lung cancer patients and about 50% of female patients, some with neuroendocrine differentiation. Adenocarcinoma often presents as a peripheral type lung parenchymal mass. Microscopically, adenocarcinoma can be seen to consist of neoplastic cuboidal and columnar cells that tend to form adenoid structures supported by a fibrous stroma. The nuclei may be large or irregular and contain distinct nucleoli, and mucin is seen in the cytoplasm. Adenocarcinoma tends to grow outside the trachea, but can also spread through the alveolar wall, often forming a mass of 2-4 cm in diameter at the lung margin. Adenocarcinoma can invade blood vessels and lymphatic vessels at an early stage, and often metastasizes before the primary cancer causes symptoms, and can easily metastasize to the liver, brain and bone, and more easily involve the pleura and cause pleural effusion. Fine bronchoalveolar carcinoma is an important subtype of lung adenocarcinoma and is receiving more and more attention due to the increasing incidence of fine bronchoalveolar carcinoma. Microscopically it is usually a single, well-differentiated, columnar cell with a basal nucleus covering the fine bronchi and alveoli. This type of lung cancer can occur in the periphery of the lung, remain in situ for a long time, or be diffuse, invading most of the lung lobes or even spreading to one or both lungs. Some scholars believe that alveolar cell carcinoma should be classified into a separate type. Fine bronchoalveolar carcinoma includes those tumors in which the tumor cells spread along the alveolar structures (squamous spread). Solitary fine bronchoalveolar carcinoma has no invasion of the stroma, pleura, or lymphatic areas. There are 3 subtypes of fine bronchoalveolar carcinoma: mucinous, non-mucinous, and mixed mucinous and non-mucinous. Adenocarcinoma includes: 1, bronchogenic alveolar carcinoma and bronchogenic papillary carcinoma; 2, fine bronchoalveolar carcinoma 3.Solid carcinoma with mucus formation.