Any manifestation of the acquired form of syphilis of the lung is a comparatively rare pathologic entity. The case herein reported, however, seems to justify the diagnosis. In reviewing the literature of recent years, we found no case in which the roentgen examination disclosed the well circumscribed appearance without associated inflammatory changes that this case presented. This was probably due to the fact that their films of the chest were made later in the course of the disease than were ours, and, therefore, at a time when secondary inflammatory changes had altered the x-ray appearance. We were unfortunate in not being able to repeat the roentgen examination during the last three months of life. The extensive secondary inflammatory changes which can accompany such a lesion were evidenced by the postmortem report of this case. Figures 1 and 2 show the x-ray appearance of the lesion three months before death. Some pathologists hold that a lesion of tertiary syphilis manifesting itself in the lung usua...