ALK-rearranged primary mixed mucinous and non-mucinous lung adenocarcinoma: A case report.

Lung cancer exhibits a diverse array of morphological manifestations and molecular changes, significantly influencing patient diagnosis, prognosis, and treatment strategies. We present the case of a 47-year-old man with a history of smoking, who presented to the emergency room with a 12-month history of haemoptysis. A chest computed tomography (CT) scan revealed a mass in the right upper lobe of the lung and bilateral lung nodules. He underwent a diagnostic wedge resection, which confirmed mixed mucinous and non-mucinous lung adenocarcinoma exhibiting acinar, papillary and micropapillary growth patterns. Molecular studies identified rearrangements in the ALK gene, and staging images revealed central nervous system and bone metastases. This case presents an unusual morphology of mixed mucinous and non-mucinous lung adenocarcinoma and highlights the importance of using immunohistochemical and molecular markers to determine tumour biology.