Ominous lung cavity “Tambourine sign”

Table 2 Learning points

IMAC is more common in non-smokers and females and has poor prognosis

It has lower lobe predominance and is frequently multifocal

IMAC may be missed on repeated cytology and biopsies due to relative paucity of malignant cells and large amount of mucin

“Tambourine” sign in appropriate clinical setting identifies lung cavity suspicious for malignancy, especially IMAC

IMAC may show unusual slow growth and only mild uptake on PET

IMAC: Invasive mucinous adenocarcinoma; PET: Positron emission tomography.