Keigo Kishino, Makiko Yomota, Hideo Arai, Yukio Hosomi
Spontaneous hemothorax, defined as bleeding into the pleural cavity without trauma or coagulopathy, is rare. Especially, it is uncommon in patients with primary epithelial lung cancer. We report a rare autopsy case of lung adenocarcinoma harboring both an anaplastic lymphoma kinase (ALK) rearrangement and a tumor protein p53 (TP53) mutation, in which hemothorax led to the formation of a giant pleural hematoma.A 75-year-old man with stage IVB lung adenocarcinoma presented with mediastinal and cervical lymph node metastases and right pleural effusion at diagnosis. Molecular testing revealed an ALK rearrangement and a TP53 mutation. He was treated sequentially with alectinib, lorlatinib, and brigatinib. After disease progression and treatment-related complications, he presented to the emergency department with acute dyspnea and a rapid decrease in hemoglobin level. Contrast-enhanced computed tomography showed encapsulated fluid retention with faint high attenuation in the right pleural cavity, and magnetic resonance imaging findings were consistent with a hematoma. Given his poor performance status and the absence of active bleeding on imaging, invasive intervention was not performed. Despite supportive management, he died one week after admission from respiratory failure and hemodynamic deterioration.Autopsy revealed a giant pleural hematoma above the diaphragm, surrounded by pleural metastases. Although no definite source vessel was identified, active bleeding from a metastatic pleural lesion was observed, suggesting persistent tumor-related hemorrhage as the cause of the hemothorax.This case represents an extremely rare presentation of ALK-rearranged lung adenocarcinoma complicated by spontaneous hemothorax. Neither ALK rearrangement nor TP53 mutation has been directly linked to hemothorax, but the aggressive biological behavior associated with this molecular profile may have contributed to the catastrophic pleural bleeding. In lung cancer patients, rapid pleural fluid accumulation with hyperdense imaging findings should raise suspicion for hemothorax.