A Case of Thoracolithiasis Extracted with a Thoracoscope.

We report on an 81-year-old male patient in whom chest computed tomography during follow-up for extramammary Paget's disease revealed a nodule in the right thoracic cavity. Because he had been taking methotrexate for rheumatoid arthritis, the possibility of methotrexate-associated lymphoproliferative lung disease was considered and methotrexate was discontinued as a precaution. No calcification was found inside the nodule, and there was no change in its size or position for 6 months. The patient had a history of malignant tumor, so thoracoscopic surgery was performed for diagnostic purposes. A free white nodule was found in the right thoracic cavity and was subsequently removed. The pathological diagnosis was thoracolithiasis; although the nodule had not moved since its discovery, movement was suspected to have occurred 3 years prior. Although thoracolithiasis is rare, it should be considered as a differential diagnosis for nodules at the end of the lung field and on the diaphragm.