Lymphangitic carcinomatosis (cancer spreading through the lymphatic system). Pulmonary veno-occlusive disease. Sarcoidosis or silicosis (due to fibrosis and scarring). Viral or mycoplasma pneumonia.
| Feature | Kerley A Lines | Kerley B Lines | |--------|---------------|----------------| | | 1951 (Kerley added them later) | 1933 | | Anatomy | Peribronchovascular interstitium | Interlobular septa | | Location | Central, upper/mid zones | Peripheral, lower zones | | Length | 2–6 cm | 1–2 cm | | Orientation | Radiating from hilum | Perpendicular to pleura | | Touch pleura? | No | Yes | | Common in heart failure | Less common | Very common | | Visibility | Requires good technique | Easily seen | | Differential | Vessels, scars, lymphangitic spread | Septal lines (any cause) |
Kerley lines represent fluid accumulation in the lung's interstitial space. The lung interstitium is divided into three compartments:
Kerley A lines are less common than B lines but indicate a similar underlying pathology. These lines are longer (2 cm to 6 cm) and radiate from the hila (the central part of the lung) toward the periphery. They do not reach the edge of the lung like B lines do.
Kerley A and B lines are thin, linear opacities seen on chest X-rays that indicate the presence of pulmonary edema or other forms of interstitial lung disease. These lines represent the abnormal thickening of the interlobular septa within the lungs, typically due to the accumulation of fluid, cellular infiltration, or connective tissue changes.
Understanding these radiographic signs is essential for diagnosing congestive heart failure and various restrictive lung conditions.
In summary, Kerley A and B lines are vital clues in thoracic imaging. Kerley B lines, in particular, serve as a reliable "red flag" for interstitial pulmonary edema, guiding clinicians toward a prompt diagnosis of cardiac or lymphatic distress.
| Finding | Distinction | |--------|-------------| | | Plate-like, often horizontal, not septal, resolve differently | | Scarring (old TB/fibrosis) | Upper zone, retracted hilum, chronic | | Lymphangitic carcinomatosis | Nodular or irregular septal thickening, unilateral or asymmetric | | Pneumonia | Focal airspace disease, no rapid diuresis response | | Normal vessels | Taper, branch, continuous with hilum |
When you spot Kerley lines on a chest X-ray:
