Placental transmogrification (PT) is an unusual condition in which the alveoli develop a peculiar villous configuration that resembles the placental villi. We report a rare case of pulmonary PT in a 46-year-old man who presented with multiple cystic lesions and nodules on radiography. The patient was treated with a surgical excision. The cut surface of the lung lesion had a villous spongiform manifestation with a partly yellow granular appearance.
Microscopically, multiple papillary cores mimicking the villous structures of the placenta were observed within the bullous airspaces. These papillary cores contained many vascular structures, lymphoid aggregates, interstitial clear cells, mature fat and dystrophic calcification. This case was solitary and not associated with other pulmonary or systemic diseases. The etiology is unknown, and further studies will be needed to understand the pathogenesis of the lesion.