A 34-year-old man on induction chemotherapy for acute myeloid leukaemia develops fever and a neutrophil count of 200/mm3. CT chest shows a 2.5 cm nodule in the right upper lobe surrounded by a rim of ground-glass opacity. What is the most likely diagnosis?

• A Kaposi sarcoma
• B Pulmonary infarct from septic embolus
• C Cryptococcal granuloma
• D Angioinvasive aspergillosis ✓

Explanation

The halo sign, a macronodule surrounded by ground-glass attenuation, in a profoundly neutropenic patient is highly suggestive of angioinvasive aspergillosis. The halo represents haemorrhage around an infarcted focus caused by fungal invasion of small pulmonary vessels. Kaposi sarcoma produces flame-shaped peribronchovascular nodules in AIDS patients, cryptococcus does not typically produce the halo sign, and septic emboli are usually multiple peripheral wedge-shaped or cavitating lesions without a surrounding ground-glass rim.

Reference: Webb, Muller and Naidich: High-Resolution CT of the Lung, 5th ed.

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Written and medically reviewed by the StethoPrep medical team.