Case 6

This is an HRCT study showing clustered nodules / nodular consolidations with surrounding ground glass opacification – exhibiting the \'halo sign\'; this is limited in distribution to the right lower lobe. There are a few minor patches of ground glass opacification in the right upper lobe. I note minor bronchiectasis in the lower lobes. Incidentally, the patient is post CABG as evidenced by sternotomy wires. There is also heavy atherosclerotic calcification of the coronary arteries denoting coronary artery disease.

These findings are most characteristic of invasive pulmonary aspergillosis, particularly in an immunocompromised patient. Other fungal infections are also possible, such as invasive mucormycosis.

The differential diagnosis for the halo sign includes haemorrhagic metastases and granulomatosis with polyangiitis, but the distribution and clustering makes these differentials far less likely.

In the first instance, I would investigate the patient’s immune status. I would raise this case for discussion at pulmonary MDT; fungal cultures and antigen tests would likely be warranted.