We report a case in which EUS-FNA was performed and pathological diagnosis was obtained for a lung mass that was difficult to diagnose by endobronchial ultrasonography using a guide sheath (EBUS-GS). A patient in his 50s with chronic pancreatitis was diagnosed with a nodule detected in the left pulmonary apex on computed tomography (CT). Three years later, the patient was referred to our hospital for EBUS-GS because the nodule showed an increasing trend on CT, but no pathological diagnosis was obtained. EUS-FNA was performed because the pulmonary mass was suspected to have invaded the mediastinum; it was possible to puncture the pulmonary mass without involving the lung parenchyma. The EUS finding from the cervical esophagus revealed a 20 mm-sized hypoechoic mass with irregular margins, which was punctured twice using a 22-gauge biopsy needle. A pathological diagnosis of lung adenocarcinoma was obtained. There was no adverse event related to EUS-FNA. Surgical resection was performed later. In conclusion, pathological diagnosis of primary lung cancer by EUS-FNA can be safely performed only in cases of mediastinal invasion adjacent to the esophagus.
