Primary pulmonary squamous cell carcinoma with colonic metastasis.

Lung cancer continues to have the highest mortality rate among cancers worldwide. At the time of diagnosis, 50% of lung cancer patients present with locally advanced or distant metastasis, commonly to the brain, bone, liver, and adrenal glands. Lung metastasis to the small bowel and colon is rare. Few cases of symptomatic colon metastasis have been reported, and it is rarely recognised clinically before severe complications occur. Our patient was a 64-year-old previously healthy male, an ex-smoker with a 20 pack-year history of smoking, who quit 4 years prior to his diagnosis of primary bronchogenic squamous cell carcinoma with local lymphatic invasion in January 2021. After two months, the patient started his scheduled treatment with multiple lines of immunochemotherapy. Follow-up in November 2022 showed disease progression, for which mediastinoscopy was performed for diagnostic evaluation, followed by palliative radiotherapy for local disease control. The patient was doing well, but after seven months, he presented to the hospital seeking medical advice due to abdominal pain and constipation for a duration of 2 weeks. A workup including a CT scan, colonoscopy, and biopsy was performed. The patient was diagnosed with poorly differentiated squamous cell carcinoma metastasis to the colon, and a right hemicolectomy was performed for palliation. In general, colonic metastasis of lung cancer is associated with a poor prognosis, with a survival range of 5 weeks to 1 year.