Placental transmogrification of the lung: Clinicopathologic, immunohistochemical and molecular study of two cases, with particular emphasis on the interstitial clear cells

Two cases of placental transmogrification of the lung are reported. The lesions presented in the left lung, in one case as a giant bulla of the upper lobe and in the other as a cystic nodule of the lower lobe. A segmentectomy was performed in both cases, and the patients were alive and well 5 years and 2 months after surgery, respectively. In our opinion, pulmonary placental transmogrificafion is not a variant of emphysema, as generally considered, but rather probably represents a benign proliferation of immature interstitial clear cells with secondary cystic change. This report presents a histological, immunohistochemical, ultrastructural and molecular study of these peculiar cells, together with a review of the literature.