<unk>  A<unk>  :These are longer (at least 2cm and up to 6cm) unbranching<unk>  coursing diagonally from the hila out to the periphery of the lungs. They are caused by distension of anastomotic channels between peripheral and central lymphatics of the lungs.<unk>  A<unk>  are less commonly seen than<unk>  B<unk> .<unk>  A<unk>  are never seen without<unk>  B or C<unk> .<unk>  B<unk>  in a patient with congestive heart failure.<unk>  B<unk>  :These are short parallel<unk>  at the lung periphery. These<unk>  represent interlobular septa, which are usually less than 1 cm in length and parallel to one another at right angles to the pleura. They are located peripherally in contact with the pleura, but are generally absent along fissural surfaces. They may be seen in any zone but are most frequently observed at the lung bases at the costophrenic angles on the PA radiograph, and in the substernal region on lateral radiographs. Causes of<unk>  B<unk>  include pulmonary edema, lymphangitis carcinomatosa and malignant lymphoma, viral and mycoplasmal pneumonia, interstitial pulmonary fibrosis, pneumoconiosis, and sarcoidosis. They can be an evanescent sign on the chest x-ray of a patient in and out of heart failure.<unk>  C<unk>  :These are the least commonly seen of the<unk> . They are short, fine<unk>  throughout the lungs, with a reticular appearance. They may represent thickening of anastomotic lymphatics or superimposition of many<unk>  B<unk> .
Kerley lines
Mees' lines
Stenvers projection
Loop mark
Cramp-ring
Gilula's lines
Surfer's knots
Beau's lines