Abstract
A 39-year-old Japanese man presented to our hospital complaining of left chest pain and rash on the hands and feet. Plain thoracic computed tomography (CT) revealed multiple nodular shadows in the left lower lobe of the lung. A diagnosis of secondary syphilis was made based on the appearance of the rash and positive serologic tests for syphilis. The patient was started on amoxicillin but was switched to minocycline due to amoxicillin-induced rash on both forearms. Thoracic CT after five months of treatment revealed that the multiple lung nodular shadows had contracted, and secondary syphilis with pulmonary involvement was diagnosed.