A mass on the lung is simply a predominant lesion that is detected by imaging, such as the use of a double lung x-ray, CT or CT-enhanced imaging, or even an MRI. It can be seen most often in benign lesions, such as inflammatory pseudotumor masses. This is mainly an inflammatory mass that forms as a fibrotic, calcified nodule when the inflammatory response reaches its final stage. This mass contains a large amount of inflammatory metabolites, metabolic calcifications, such as those left after complete healing of Mycobacterium tuberculosis infection. It is also seen in relatively rare benign tumors, such as malignant tumors, teratomas, and stones in the lungs. It is also seen in malignant tumors, including bronchopulmonary carcinoma and alveolar cell carcinoma presenting with cancerous masses. The nature of the mass can be clarified by taking a biopsy of the mass for pathological examination.