Introduction Lung cancer is the most common cause of cancer-related deaths globally. Metastatic disease is often found at the time of initial diagnosis in the majority of lung cancer patients. However, colonic metastases are rare. This report describes an uncommon case of colonic metastasis from lung adenocarcinoma. Case presentation A 64-year-old female presented to her gastroenterologist for progressively worsening abdominal pain and constipation. Exploratory colonoscopy revealed a large rectosigmoid mass resulting in near total rectal occlusion. Her specialist recommended she immediately go to her regional hospital for further workup. On admission, she complained of continued abdominal pain and constipation. Notably, she had a past medical history of non-small cell lung cancer (T1bN3M0 stage IIIB), diagnosed 1 year prior. She was thought to be in remission following radiation and immunotherapy with pembrolizumab. Upon hospital admission, she underwent an urgent colostomy, ileocecectomy and anastomosis, and rectosigmoid mass resection with tissue sampling. Pathology confirmed the diagnosis of colonic metastasis from primary lung adenocarcinoma. Treatment was with systemic chemotherapy followed by localized radiation to the pelvic region was started. She did not respond well to these therapies. Subsequent imaging showed refractory tumor growth in the pelvic region. Treatment could not be completed due to the patient experiencing a debilitating stroke, and she was transitioned to hospice care. Conclusions Clinicians should have a low threshold for intestinal investigation and considerations for colonic metastasis when patients with a history of primary lung cancer have abdominal symptoms.

A 55-year-old female presented to the emergency department with seizures, left hemiparesis, and memory loss. Her past medical history was notable for a right triple-negative breast adenocarcinoma that was diagnosed approximately two years prior. She underwent treatment with chemotherapy, right breast lumpectomy, and radiation near her rural hometown. Radiologic studies were performed in the emergency department. Brain imaging revealed a new 2-cm mass in the left breast and a 4-cm left frontal lobe brain lesion. She underwent an urgent craniotomy. Immunohistochemical staining of the brain tumor tissue suggested metastatic triple-negative breast adenocarcinoma. She was discharged with recommendations to follow up with her prior oncologist near her home for systemic chemotherapy. Three months after metastatic breast cancer to the brain was diagnosed, the patient experienced headaches, fever, and nuchal rigidity. MRI of the brain showed new leptomeningeal enhancement. A lumbar puncture with a cerebrospinal fluid analysis revealed the presence of malignant cells. Together with imaging and cerebrospinal fluid findings, leptomeningeal carcinomatosis was diagnosed. This case report presents an uncommon but well-known complication of breast cancer.

Colonic metastases are extremely rare, regardless of primary lung cancer type. A 64-year-old female was referred to the hospital by her gastroenterologist after a same-day colonoscopy revealed a large rectosigmoid mass resulting in near total rectal occlusion. On admission, she complained of abdominal pain and constipation. She had a past medical history of non-small cell lung cancer (T1bN3M0 stage IIIB), diagnosed one year prior. She was thought to be in remission following radiation and immunotherapy with pembrolizumab. She underwent urgent surgical intervention and mass resection with tissue sampling. Pathology confirmed the diagnosis of metastatic lung adenocarcinoma. Systemic chemotherapy with pemetrexed and carboplatin followed by localized radiation to the pelvic region was administered. A refractory pelvic region tumor growth was evident on subsequent imaging. Cessation of chemoradiation therapy occurred after the patient experienced a debilitating stroke and she was transferred to hospice care. Colonic metastasis should be considered when patients with a history of primary lung cancer have abdominal symptoms.