This is a radiograph of a young lady. There is a 1cm rounded opacity in the right lower zone. At first look, it is consistent with a solitary pulmonary nodule (SPN).
But look at it again closely. There is a faint larger shadow without any margin around it. This is her right breast shadow and the smaller nodule is her right nipple.
On the contra-lateral side, there is a similar shadow in the left lower zone. However, the breast shadow is not very obvious. This is her left nipple.
Always be careful of nipple shadow as it can mimics pulmonary nodule. Nipple shadow is usually in the 5th intercoastal space. If you are still unsure, repeat the radiograph with a nipple marker on it. Nipple marker can be any metallic object such as a paper clip plastered lightly on the nipple. If the shadow falls exactly on the marker, then the nodule is just a nipple shadow.