Symptomatic colon
metastasis from primary
lung cancer is rare in clinical practice. We report the case of a 58-year-old patient with advanced
lung adenocarcinoma who developed abdominal symptoms, including abdominal distention and difficulty defecating, after
immunotherapy and
chemotherapy. The patient was diagnosed with
lung adenocarcinoma, and systemic positron emission tomography-computed tomography confirmed multiple lymph node, pleural, and adrenal
metastases. Molecular detection indicated BRAF V600E mutation and high
programmed death-ligand 1 (PD-L1) expression. After first-line anti-
programmed cell death protein 1 immunotherapy combined with
chemotherapy, the nodes in the chest remarkably diminished. However, it was followed by colon obstruction, incomplete
ileus, and bone
metastasis. Endoscopic histological examination confirmed
adenocarcinoma but could not identify primary or secondary
tumors due to insufficient tissue. We performed colon resection to remove the obstruction, and postoperative tissue pathological microscopy confirmed
metastasis from the
lung adenocarcinoma. We corroborated the BRAF V600E mutation and high PD-L1 expression and supported the molecular features of
lung adenocarcinoma. During hospitalization, the patient presented with unbearable
pain in the bone
metastases, and palliative
radiotherapy was administered. Then, the patient received
dabrafenib plus
trametinib as the second-line
therapy. This report discusses the clinical characteristics, pathology, imaging, molecular profile assessments, and treatment of primary
lung adenocarcinoma with colon
metastasis.