Metachronous multifocal placental transmogrification of the lung: a nodular subtype with microscopic emphysematous...

Placental transmogrification of the lung (PTL) is a rare benign pulmonary lesion with limited longitudinal data. It is most often associated with unilateral bullous disease, but may also present as a solitary pulmonary nodule.

A 49-year-old man underwent video-assisted thoracoscopic wedge resection of a 12-mm right upper lobe pulmonary nodule detected on screening chest computed tomography (CT). Histopathology confirmed nodular-type PTL. Seven months later, surveillance CT revealed a new 10-mm solid nodule in the right lower lobe. The lesion persisted on follow-up imaging and was resected 12 months after the initial operation. Histological examination confirmed PTL and demonstrated focal microscopic emphysematous remodeling despite the absence of bullous changes on preoperative CT. This radiologic-pathologic discordance suggests that microscopic emphysematous remodeling may precede radiologically apparent bullous transformation.

Metachronous multifocal PTL may arise in different ipsilateral lobes after complete resection of the index lesion. These findings support the need for structured postoperative surveillance, particularly during the early period after resection.