Placental villotrophoblastic pulmonary emboli after elective abortion: immunohistochemical diagnosis and comparison with ten control cases.

Although pulmonary trophoblastic embolism is now considered a physiologic phenomenon of normal pregnancy, this phenomenon has not been demonstrated in a living asymptomatic patient. Recently we encountered a 26-year-old woman suspected of pulmonary embolism of villotrophoblastic tissues after therapeutic abortion. Although her serum beta-hCG was low, a computed tomography scan showed multiple nodules in both lungs. Histological examination of a nodule in a lung-biopsy specimen showed granulation tissue surrounding a hemorrhagic mass within which were structures resembling degenerating chorionic villi. Immunohistochemical study on the patient's lung nodule, and a second endometrial-curettage specimen, six control endometrial and tubal specimens containing degenerating chorionic villi, and four endometrial specimens containing viable chorionic villi were performed. The patterns of immunostaining for cytokeratin, human chorionic gonadotropin, human placental lactogen, placental alkaline phosphatase, and inhibin-alpha of the chorionic villus-like structures in the lung nodule were almost identical to those in the degenerating chorionic villi, but different from those of viable villi. This is a unique case of embolism of chorionic villi and trophoblast to the lung in a living patient after therapeutic abortion.