Small calcification foci in the outer basal segment of the lower lobe of the left lung are localized foci formed by abnormal hyperplasia and necrosis of part of the lung tissue in the outer basal segment of the lower lobe of the left lung caused by diseases such as tuberculosis, pneumonia, or lung tumors, which releases calcium salts for deposition. Most of the calcifications are benign and usually do not require treatment, while a few are calcifications of lung cancer and may require surgical resection. 1. Benign calcification: most common in tuberculosis, the calcification foci are diffusely distributed or almost completely calcified, layered or central nest-like distribution of calcification, or contain fat and “popcorn” like calcification. 2. Calcification of lung cancer: speckled or irregular calcification, often combined with features such as “vacuoles” or “burrs”. Small calcification foci in the extra-basal segment of the lower lobe of the left lung, it is recommended to go to the hospital for further consultation and diagnosis.