Four corners sign (CT chest)

The four corners sign describes an axial CT feature seen in some forms interstitial lung disease where affected regions disproportionately involve the bilateral anterolateral upper lobes and posterosuperior lower lobes. Reticular opacities, ground-glass attenuation and/or honeycombing appear distributed in all four corners of the thorax on the same axial image. It is thought be characteristic of interstitial lung disease associated with systemic sclerosis ¹.

See also

• scleroderma (pulmonary manifestations)

• propeller blade distribution