Slightly dense nodular foci are seen under the pleura of the right apical lung, which may be caused by pneumonia, tuberculosis, lung malignant tumors, and so on. 1. Pneumonia: Mostly caused by bacteria, viruses, anaerobic bacteria and other pathogens causing lung infection. It can produce a large amount of inflammatory exudate, which collects in the right apical part of the lung, and the CT examination can see high-density nodular foci, which is often accompanied by symptoms such as cough, shortness of breath, fever, and so on. 2. Tuberculosis: mostly caused by Mycobacterium tuberculosis, the lesion involves the right apical part of the lung, and can be seen as high-density nodular foci, often accompanied by symptoms such as low-grade fever, chest pain, and fatigue. 3. Malignant tumor of lungs: when the tumor occurs in the lungs, the tumor cells infiltrate the normal lung tissues in large quantities, leading to tissue necrosis, which can be seen as high-density nodular foci in the right apical part of the lungs, mostly accompanied by irritating dry cough, sputum, dyspnea and other symptoms. The presence of subpleural high-density nodular foci in the right lung apical region should seek medical treatment in time to prevent delay of the disease.