Squamous cell carcinoma of lung is mostly central lung cancer, which is easy to grow into the lumen and often leads to bronchial stenosis or obstructive pneumonia in the early stage. And because of the degeneration and necrosis of cancer tissue, a cavity or cancerous lung abscess is formed. Lung squamous cell carcinoma grows slowly and spreads and metastasizes later. Squamous cell carcinoma of lung is usually white or gray, with hard texture and local carbon-like pigmentation, depending on the degree of fibrosis. In the center of the lesion, it extends backwards in a star shape.
Central lung squamous cell carcinoma is often accompanied by the formation of huge cavities. The central tumor can form a polypoid mass in the cavity and infiltrate the surrounding tissues through the bronchial wall. It can also block the bronchial cavity, leading to the accumulation of bronchial secretions, atelectasis, bronchiectasis, obstructive lipomatosis pneumonia and infectious bronchopneumonia. A few cases may originate from peripheral small airways. It is reported that 53% squamous cell carcinoma occurs in the surrounding lungs.
Central squamous cell carcinoma is characterized by two diffusion modes: intraepithelial diffusion and bronchial polypoid growth. Intraepithelial diffusion is common in the main bronchus. Bronchial glands or duct epithelium are often invaded. Two growth modes of early invasive lung squamous cell carcinoma have been described: one is along the mucosa of one side of bronchus instead of superficial epithelium, accompanied by submucosal micro-infiltration and glandular duct infiltration; The other is a small polypoid mucosal lesion with deep infiltration. Direct invasion of hilar mediastinal tissue including lymph nodes can be seen in advanced cases.
Peripheral squamous cell carcinoma is characterized by the formation of solid nodules, usually accompanied by nodular growth in bronchi, intraepithelial diffusion or both. In advanced cases, peripheral squamous cell carcinoma can directly invade the chest wall or diaphragm through the pleura.
Etiology of lung squamous cell carcinoma
The etiology of lung squamous cell carcinoma is closely related to smoking. Clinical data show that more than 90% of lung squamous cell carcinoma occurs in smokers. In addition, the study found that arsenic is also closely related to the occurrence of squamous cell carcinoma.
Staging of lung squamous cell carcinoma
The staging of lung squamous cell carcinoma is usually carried out according to TNM method. Generally speaking, lung squamous cell carcinoma tends to invade local adjacent tissues through direct diffusion. Compared with adenocarcinoma or other primary lung cancer tissue types, lung squamous cell carcinoma has less distant organ metastasis. Peripheral lung squamous cell carcinoma with a diameter less than 2cm rarely has local lymph node metastasis. Low-differentiated lung squamous cell carcinoma can metastasize to brain, liver, adrenal gland, lower digestive tract and lymph nodes in the early stage. Local recurrence of lung squamous cell carcinoma after surgical resection is more common than other types of lung cancer.