Mature Teratoma of the Cerebellum with Formed Extracranial Component

<b>Background:</b> Intracranial teratomas are very rare in adults, representing only 0.3-0.5% of all primary brain tumors. They originate from all three germ layers, and are classified as mature, immature, or malignant. Mature teratomas constitute the most prevalent type in the adult population, commonly originating from midline structures such as the pineal and suprasellar regions. However, the localization of these tumors within the cerebellum is exceedingly rare, with only a limited number of cases reported globally. In this manuscript, we describe, to the best of our knowledge, the first documented case of a young adult patient presenting with a mature teratoma situated between the cerebellar hemispheres. Notably, this tumor was accompanied by occipital bone loss, through which a tumor pedicle extended, forming an extracranial component. <b>Methods</b>: After analyzing the clinical picture and additional examinations, the patient was classified for surgery. The intracranial part of the tumor contained numerous cysts with yellow fluid, a tooth, and fat tissue. The tumor was removed radically, with its extracranial part. <b>Results</b>: On the fourth day after surgery, the patient was discharged from the clinic in a good general condition, walking, with marked cerebellar symptoms. In a follow-up at 6 months postoperatively, the neurological examination was normal, with no headaches. MRI at the 6 months follow-up did not show any residual or recurrent tumor. <b>Conclusions:</b> Histopathological examination confirmed the diagnosis of mature teratoma.