Kerley A,B and C Signs Chest X-ray

In patients with INTERSTITIAL LUNGS Disease, fluid or cellular infiltration of inflammatory (edematous) fluids into the interstitium of lungs causes thin pulmonary opacity; this presents a radiographic opacity along the alveoli, known as Kerley Sign.

Behind the Scene:

[A] Cardiac
a. Congestive Heart Failure( Left Sided Heart Failure)

[B] Extracardiac
a. pulmonary fibrosis
b. interstitial deposition of heavy metal particles (Pneumoconiosis)
c. carcinomatosis of the lung

TYPES OF KERLEY SIGNS

Kerley A lines
These signs present as a diagonal lines with its course from the hilum of the lungs and extends out to the periphery of the lungs which is caused because of the anastomotic channel distention between the central lymphatics of the lungs and the peripheral draining lymph vessels. Kerley A sign is a must when Kerley B and/or C lines are seen. However, this sign itself is quite rare.

Kerley B lines
Kerley B sign present as a short parallel lines across the outward pheripheral zone of the lungs along the pleura. Those interlobar septated area are right angle to the pleura but are absent along the fissure and are most commonly reported from the zone III of lungs along Costophrenic angle(PA View) and in substernal region on lateral view.
Causes:
i. pulmonary edema
ii. lymphangitis carcinomatosa
iii. malignant lymphoma
iv. viral and mycoplasmal pneumonia
v. interstitial pulmonary fibrosis
vi. pneumoconiosis
vii. sarcoidosis
 They can be an evanescent sign on the chest x-ray of a patient in and out of heart failure.

Kerley C lines
Kerley C lines are most rare. These lines present as short and fine lines with reticular appearance along the lungs parenchyma.