case_images: PMC8203063_01
case_images: Chest X-ray image showing complete opacification of the left lung.
case_images: AJTCCM-27-1-048-fig1.jpg
case_images: PMC8203063_01_AJTCCM-27-1-048-fig1.jpg
case_images: F1
case_images: A chest X-ray image at the time of initial assessment revealed complete opacification of the left lung with associated air bronchogrammes noted in the left perihilar region (Fig. 1).
case_images: Chest computed tomography image confirming consolidation of the left lung
case_images: AJTCCM-27-1-048-fig2.jpg
case_images: PMC8203063_01_AJTCCM-27-1-048-fig2.jpg
case_images: F2
case_images: Chest computed tomography analysis confirmed dense consolidation of the left lung with no evidence of atelectasis or pleural effusion (Fig. 2).   In view of the clinical problem of a non-resolving pneumonia, the differential diagnoses included atypical pneumonia, non-tuberculous mycobacterial disease, primary lymphoma of the lung and slow-growing primary lung neoplasms.
case_images: Intermediate magnification micrograph of lung biopsy histology revealing lepidic growth pattern of neoplastic cells after haematoxylin and eosin staining
case_images: AJTCCM-27-1-048-fig3.jpg
case_images: PMC8203063_01_AJTCCM-27-1-048-fig3.jpg
case_images: F3
case_images: T-cell response. Transbronchial lung biopsies, however, revealed tumour tissue with the appearance of a well-differentiated mucus-secreting adenocarcinoma with lepidic features (Fig. 3).  Immunohistochemical staining for cytokeratin 7 (CK7), thyroid transcription factor-1 (TTF-1) and napsin