A case of benign, cystic intrapulmonary teratoma occurring in the right lob
e of a 22-year old female is described with grossly and microscopically fin
dings. The connection between the tumor and the segmental bronchus, togethe
r with the absence of germ cell neoplasms in other locations, clearly estab
lished the true intrapulmonary nature of the lesion. The unusual finding of
thymic tissue within the wall supports the possible origin from the third
pharyngeal pouch.