A Rare Presentation of Poorly Differentiated Lung Carcinoma with Duodenal Metastasis and Literature Review

Lung cancer is a common malignancy which is frequently found to metastasize to distant sites including bone, liver, and adrenal glands. There are rare reports of metastases to the gastrointestinal (GI) tract, with the duodenum being the most uncommon. We present a rare case of a poorly differentiated lung carcinoma metastasizing to the duodenum. This case enhances the medical literature as it provides additional distinct features to the clinical and histological presentation of metastatic lung carcinoma to the GI tract. A 61-year-old male with a history of poorly differentiated lung carcinoma presented with worsening dizziness, fatigue, and early satiety. He had extensive workup done in the past for hemoptysis including a computerized tomography scan of the chest which showed a new lobulated, apical lesion and hilar lymphadenopathy. He ultimately had a transthoracic fine-needle aspiration (FNA) of the mass and was later diagnosed with poorly differentiated lung carcinoma. On examination, the patient was noted to be pale, tachycardic, and hypotensive. The patient was noted to have an acute drop in his hemoglobin requiring fluid resuscitation, multiple blood transfusions, and evaluation with an esophagogastroduodenoscopy. He was found to have an oozing ulcer in the third portion of the duodenum whose biopsies showed poorly differentiated carcinoma with areas of neuroendocrine differentiation, similar to his lung biopsy results, which was consistent with metastatic lung carcinoma.