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Mature teratoma of the uterine cervix with pulmonary differentiation.

Teratomas of the uterus are very rare, and a uterine teratoma with pulmonary differentiation has not, to our knowledge, been described previously. In this article, we report such a case in a 33-year-old woman, who presented with heavy vaginal bleeding and a polypoid mass of the uterine cervix. The cervical lesion was composed entirely of mature lung tissue, including bronchial, bronchiolar, and alveolar structures. The presence of well-differentiated respiratory epithelial cells, ie, Clara cells and alveolar type II cells, is confirmed by immunohistochemistry. The patient had no history of dilatation and curettage; therefore, implantation of fetal tissue could be excluded from the differential diagnoses. Since this is a newly developed mass in an adult individual, we favor a neoplastic process over heterotopia and interpret the lesion as unilateral lung development in an extragonadal mature teratoma.