Lung Cancer of Unknown Primary Site with EGFR Mutation as Indicated by Frozen Bone Specimen

A 75 year-old Japanese women was referred to our hospital complaining of left-sided chest pain. Her performance status (ECOG) was 1. She was a never smoker. On physical examination, there was no palpable mass on her trunk or extremities. Blood examination showed significant elevation of Carcinoembryonic Antigen (CEA) to 209.5 ng/ml. Chest-X rays and Computed Tomography (CT) did not detect the primary lesion in her lung or pleura. Positron Emission Tomography and Computed Tomography (PET-CT) detected abnormal FDG uptake of left 5th and 6th rib and subaortic (Botallo's) lymph nodes (standardized uptake value-max 5.0