Primary intrapulmonary thymoma (PIT), which is an intrapulmonary tumor without an associated mediastinal component, is rare. We herein report a resected case of PIT in a 55-year-old female who presented with a 2.5 × 2.4 cm mass in the left upper lobe. We also summarize the clinicopathological features and discuss the diagnosis, pathogenesis, and treatment of PIT.