Pneumonic-type lung metastasis from rectal cancer mimicking refractory pneumonia

An 83-year-old man with a history of heavy smoking and chronic obstructive pulmonary disease (COPD) was referred for non-resolving pneumonia. Despite 6 weeks of antibiotic therapy, his respiratory status deteriorated. Chest computed tomography (CT) revealed dense consolidations with prominent air bronchograms in the right lower and left upper lobes, mimicking lobar pneumonia (Fig. 1). No nodular shadows suggestive of hematogenous metastasis were observed. Transbronchial cryobiopsy from segment 8 (S8) of the right lower lobe demonstrated tall columnar cells with abundant intracellular mucin replacing the alveolar lining (Fig. 2A). Immunohistochemical staining was negative for TTF-1 (Fig. 2B) but positive for CK20, CDX2, and SATB2 (Fig. 2C). This immunoprofile, particularly SATB2 positivity, strongly supports a lower gastrointestinal origin [1]. Subsequent colonoscopy identified a rectal tumor pathologically identical to the lung lesion. Following diagnosis, the patient’s respiratory status deteriorated rapidly, precluding initiation of systemic chemotherapy, and he died 4 weeks after the initial presentation.