The objective was to analyse the potential of CT to distinguish pneumonic-type bronchioloalveolar cell carcinoma (BAC) from infectious pneumonia. The study consisted of 21 patients with pathologically proven BAC and 30 patients with infectious pneumonia. Both groups of patients had patchy or diffuse consolidation of more than half the area of a lobe or lobes on CT. CT findings in these two groups were compared with regard to morphological appearance, including CT angiogram, air bronchogram, mucous bronchogram, contrast enhancement pattern, pseudocavitation, cavity with air-fluid level, location, satellite lesion, ground-glass opacity and bulging of the interlobar fissure. Air-filled bronchi were morphologically analysed as dilatation, stretching, sweeping, widening of the branching angle, squeezing and crowding. Lymphadenopathy and pleural effusion were also analysed. CT findings favouring the diagnosis of BAC included an air-filled bronchus within the consolidation with stretching, squeezing, sweeping, widening of the branching angle and bulging of the interlobar fissure (p<0.05). It is concluded that CT may be helpful in differentiating pneumonic-type BAC from infectious pneumonia if the air-filled bronchus within the consolidation shows stretching, squeezing, widening of the branching angle or bulging of the interlobar fissure.

A 63-year-old woman presented with obstructive jaundice. Patient was diagnosed as stage III lung adenocarcinoma 3 years ago, and underwent surgery and concurrent chemoradiotherapy. Immunostaining revealed positivity for thyroid transcription factor-1 (TTF-1) and cytokeratin (CK) 7, and negativity for CK20. Fluorescent in situ hybridization test revealed tyrosine kinase inhibitor (ALK) gene rearrangement. However, right buccal metastasis with no other metastasis was found, and she had been followed up with palliative radiotherapy. Laboratory tests showed elevated total bilirubin (9.9 mg/dL [reference value, 0.2-1.2 mg/dL]). Abdominal computed tomography (CT) showed 2.4 cm ill-defined mass with abrupt narrowing at distal common bile duct (CBD) (Fig. 1A,