BRAF V600Q-mutated lung adenocarcinoma with duodenal metastasis and extreme leukocytosis

Driver mutations in patients with non-small cell lung cancer (NSCLC) can lead to distinct behaviors and patterns of metastasis. Mutations in the proto-oncogene B-raf (BRAF) occur in approximately 3% of NSCLC cases. In the literature, reports of patients with lung adenocarcinomas metastasizing to the duodenum are rare, and most of the only 21 cases reported were from before the advent of next-generation sequencing. We present here a case involving a 57-year-old female who had a lytic lesion in her lesser trochanter. Biopsy showed metastatic adenocarcinoma of lung origin. Chest X-ray showed a large left upper lobe mass. Next-generation sequencing analysis confirmed the presence of BRAF V600Q mutation. The patient presented with persistent anemia and melena. Esophagogastroduodenoscopy confirmed the presence of duodenal metastasis. She also had suspected paraneoplastic leukemoid reaction. To our knowledge, this is only the second well-documented case of gastrointestinal metastasis from BRAF-mutated lung cancer.