A number of benign and malignant tumors occurring in the lungs but the primary lung cancer, commonly termed bronchogenic carcinoma, is the most common. The lung is also the commonest site for metastasis from carcinomas and sarcomas. A histological classification of various benign and malignant tumors of lungs as recommended by the World Health Organization
It is the most common primary malignant tumor in men industrialized nations and accounts for nearly one-third of all cancer deaths in both sexes. Currently, the incidence in females in the United States has already exceeded breast cancer as a cause of death in women. Cancer of the lung is a disease of middle and late life with peak incidence in 5th to 7th decades, after which there is a periodic fall in its incidence.
2. Atmospheric pollution
3. Occupational causes
4. Dietary factors
5. Genetic factors
6. Chronic Scarring
Tissue response in tuberculosis representations classic example of chronic granulomatous inflammation in humans.the causative agent is tubercle bacillus or Kochys bacillus called Mycobacterium tuberculosis causes tuberculosis in the lung and other tissues of the human body. The organism is a strict aerobe and thrives best in tissues with oxygen tension like in the apex of the lung.
Mode Of Transmission
1. Inhalation of organisms present in fresh cough droplets or in discharged sputum form an open case of pulmonary tuberculosis.
2. Ingestion of the organisms leads to development of tonsillar or intestinal tuberculosis. This mode of infection of human tuberculosis bacilli is from self-swallowing of infected sputum of an open case of pulmonary tuberculosis, or ingestion of bovine tubercle bacilli from milk of diseased cows.
3. Inoculation of the organisms into the skin may rarely occur from infected postmortem tissue.