Hilum convergence sign | Radiology Signs

Answer:

Hilum convergence sign indicates pulmonary artery dilatation rather than hilar mass or nodal enlargement, seen when pulmonary vessels converge toward the lateral margin of the hilar opacity. It is associated with conditions causing pulmonary hypertension such as idiopathic pulmonary arterial hypertension, chronic thromboembolic pulmonary hypertension, or left-to-right shunts.

Why is it called so?:

The sign is named for the radial convergence of normal pulmonary artery branches toward the enlarged pulmonary artery at the hilum, mimicking a focal point of vessel ingathering on chest radiograph. It was described by Benjamin Felson and originally termed the “hilus bifurcation sign.”

Pathophysiology

Pulmonary hypertension leads to dilatation of the main and proximal pulmonary arteries, enlarging the hilar shadow while preserving the normal branching pattern of pulmonary vessels that radiate outward from the central artery, distinguishing vascular etiology from mass effect where vessels converge toward the heart waist instead.

Alternative names: Hilus bifurcation sign

Other associated named signs: Hilum overlay sign (used to localize a hilar or juxtahilar opacity as anterior or posterior to the hilum)

References

1. Felson B. The mediastinum. Semin Roentgenol. 1969;4(1):41-58.