RESUMO
Mature fetiform teratoma, or homunculus, is a term coined for a rare variant of teratoma with a prevalence of 0.01% of teratomas. There have been very few cases reported in the world, and its thoracic presentation is extremely unusual. We present the case of a 31-year-old female patient with a history of progressive chest pain in the left hemithorax, associated with dyspnea on moderate exertion and cough. Imaging studies revealed a large intrathoracic tumor visually compatible with a teratoma. Surgical resection by a clamshell approach was successful, and subsequent anatomopathological studies of the operative specimen concluded that the mass was a mature fetiform thoracic teratoma. The treatment of this entity is generally surgical and includes wide resection due to its large adhesive component to surrounding tissues. Thus, the cardiothoracic surgeon must know approaches that allow wide resection, making these cases true surgical challenges.