RESUMO
INTRODUCTION: Klippel-Feil syndrome is characterized by a congenital fusion of cervical vertebrae. Intracranial teratomas are nongerminomatous germ cell tumors and they account for 0.3 to 0.9% of all intracranial tumors. Teratomas with malignant transformation refer to lesions which give rise to malignant cancer of somatic type. The association between tumors of dermoid origin and Klippel-Feil malformation is extremely rare. Only 23 other cases have so far been reported, and only one case of dermoid tumor with areas of dedifferentiation on squamous cell carcinoma has been described. CASE PRESENTATION: We report the case of a 72-year-old white man with a 2-year history of gait and balance disturbances. A brain magnetic resonance imaging revealed a fourth ventricle neoplastic process with infiltrative features. He was operated through a suboccipital craniectomy with a C1 laminotomy and bilateral vertebral artery transposition. At 6-months follow-up, magnetic resonance imaging showed an early regrowth of the fourth ventricle tumor, with the same radiological features. CONCLUSIONS: Patients with Klippel-Feil malformation could develop posterior fossa dermoid tumors. The malignant potential of such tumors must be considered and surgery is recommended. Particular attention must be focused on the histopathological analysis in order to identify possible foci of malignant transformation.