Question: What is the ‘sign’ demonstrated below on the CT chest and name one condition that you might see this sign in.

Response: This is “halo sign.” In this image the “halo sign” is what is demonstrated by the ground-glass attenuation that surrounds the spiculated mass on the right. This can be seen in the setting of infectious diseases such as fungal infections (pulmonary Aspergillosis), neoplastic processes, as well as inflammatory conditions (such as Granulomatosis with polyangiitis).

Other references:

“Lee YR, Choi YW, Lee KJ, Jeon SC, Park CK, and Heo J. CT halo sign: the spectrum of pulmonary diseases. BJR 2005; 78: 933″ https://www.birpublications.org/doi/epub/10.1259/bjr/77712845