Hello, Upper lobe emphysema is usually seen in people who have smoked. It is a dilatation of the air sacs in the lungs. Lymphoid tissue is just the immune tissue becoming prominent in the lungs. Atelectasis means collapse or flattening of the air sacs so that the part of the lung with atelectasis is not helping with oxygen exchange. If it is a small portion, it is not of much concern. But it is watched to make sure it is not getting worse or no mass is growing around it that may have been the cause of the atelectasis. All the best.