According to Northwestern Health Sciences University, apical pleural thickening is a condition of the lungs where the pleural membrane (the area around the lungs) of the apical region (the rounded top of the lungs) becomes thicker, making normal respiration difficult. With this condition, it is very common to see scarring or calcification of the pleural membrane.
Many times pleural thickening is associated with exposure to asbestos. When it is localized to a single area, in this case the apical region, it is usually the result of infection and it can be cleared up by a round of prescribed antibiotics. When caused by non-infective variables, such as asbestos or drug abuse, the damage is irreversible.