Generally, cavities have walls that are at least 5 mm thick, while cysts have walls that are 4 mm or less, and often less than 2 mm.The distinction between cysts and cavities is important because the thicker the wall is, the more likely it is to be cancer. Thus, cystic lesions are unlikely to be cancer, while cavitary lesions are often caused by cancer. In a study from 1980 that used chest X-rays to evaluate 65 cases of solitary lung cavities, 0% percent of cavities with walls 1 mm or less were malignant (that is, cancerous), versus 8% of cavities with walls 4 mm or less, 49% of cavities with walls 5 to 15 mm, and 95% of cavities with walls 15 mm or greater. However, a 2007 study that used CT to evaluate lung cavities showed no relationship between wall thickness and the likelihood of malignancy. It did show that malignant cavities are more likely than benign cavities to have an irregular internal wall (49% vs 26%) and have an indentation of the outer wall of the cavity (54% vs 29%).Areas of emphysema are abnormal, air-filled spaces that usually do not have visible walls, and bullae are very thin walled (<1 mm). Cystic bronchiectasis is irreversible bronchial dilation, which is permanent widening of the bronchioles (small airways) in the lung. It can be distinguished on imaging by a lack of bronchial tapering, meaning that the bronchioles do not get narrower as they travel further into the lung.
Fluorosis may refer to:

Dental fluorosis, a disturbance of dental enamel caused by excessive exposure to high concentrations of fluoride during tooth development. Skeletal fluorosis, a bone disease caused by excessive accumulation of fluoride in the bones
Fluoride toxicity, elevated levels of the fluoride ion in the body