A lobulated mass in the left lower lobe: not what it seems

A 43-year-old asymptomatic woman with no history of smoking was referred to our hospital because of decreased radiolucency in the left lower lung field (figure 1A), which was found by chest X-ray performed as part of a routine investigation during a medical check-up. No abnormal shadow was recognised by chest X-ray performed two years previously (figure 1B). Initial laboratory data included a white blood cell count of 4710/μl (neutrophils, 48.6%) and a C-reactive protein level of 0.03 mg/dL. Chest enhanced CT revealed a solitary lobulated low attenuation mass with septal enhancement, approximately 6 cm in diameter, across the left lateral and posterior basal segments (figure 1C-D). The internal structure appeared multilocular and was filled with fluid. A small part of the margin of the mass was accompanied by stippled calcification (figure 1D-E). Bronchoscopic examination was performed on suspicion of pulmonary mucinous cystadenocarcinoma (PMCAC). However, the forceps could not reach the mass. Bronchial lavage bacterial culture, acid-fast bacillus smear (Ziehl-Neelsen stain) and PCR tests for …