Metachronous Multifocal Placental Transmogrification of the Lung: A Nodular Subtype with Microscopic Emphysematous Changes

Placental transmogrification of the lung (PTL) is a rare benign pulmonary lesion with limited longitudinal data. We report the case of a 49-year-old man who underwent video-assisted thoracoscopic surgery wedge resection of a 12-mm right-upper-lobe pulmonary nodule subsequently diagnosed as PTL on histopathology. Seven months after surgery, surveillance chest computed tomography (CT) revealed a newly developed 10-mm solid nodule in the right lower lobe, which was resected 12 months after the initial operation and was confirmed as PTL. This case demonstrates metachronous multifocal disease arising in different ipsilateral lobes after complete resection. Histologic examination of the second lesion was consistent with PTL and showed microscopic emphysematous remodeling, despite the absence of bullous changes on preoperative CT. This finding indicates radiologic–pathologic discordance, suggesting that microscopic emphysematous remodeling precedes radiologically apparent bullous changes. The observed temporal course supports the need for structured postoperative surveillance, particularly during the early postoperative period.