Not all tumors in the lungs are lung cancer. Primary lung cancer is only a part of lung tumors, and there are other tumors in the lungs besides primary lung cancer. There are benign tumors as well as other malignant tumors. The most common benign tumors are inflammatory pseudotumors, sclerosing hemangiomas, and tuberculosis balls. These benign tumors generally do not require special treatment, and most of them are harmless, except when they are unusually large or when there is a risk of bleeding, when surgical removal can be considered. In addition to primary lung cancer, malignant tumors include sarcomas of the lungs originating from mesenchymal tissue and primary lymphomas of the lungs, which are, of course, very rare. Besides, malignant tumors in the lungs have metastasis from other places, i.e. metastatic lung cancer, which does not belong to the standard sense of primary lung cancer, and is not originated in the lungs but metastasized from other places, so primary lung cancer is only a part of lung tumors.