Occipital dermal sinus associated with infectious teratoma in an adult patient affected by Klippel-Feil syndrome: Rare case report and literature review.

Background: The Klippel-Feil syndrome (KFS) is a rare congenital anomaly characterized by the fusion of cervical vertebrae, which may be associated with other malformations, such as dermoid tumors and teratoma. Some theories explain the embryology of these associations. Another condition that may be present is the dermal sinus (DS), communication between intracranial tumors and the subcutaneous tissue, and predisposing infections. This case report aims to describe an association between these three pathologies as well as correlate them from the literature. This report was based on medical records retrospectively reviewed associated with the systematic bibliographical consultation using indexed databases based on inclusion and exclusion methods. Case Description: An adult male patient, 24 years old, was admitted to our service, presenting fever and meningeal irritation as initial symptoms. In the patient's clinical history, he was diagnosed with an occipital DS in his childhood, which was previously instructed to be operated on by another neurosurgical team, but the patient chose not to perform the procedure. The magnetic resonance imaging investigation showed a DS associated with a cerebellar infected mass with 2 cm on its main diameter. The patient was treated with preoperative antibiotic therapy and underwent gross total surgical resection of the tumor as well as DS correction, confirmed in the histopathological examination as a teratoma. After surgery, further computed tomography scan analysis showed the presence of cervical vertebrae fusion, compatible with KFS diagnosis. Conclusion: The association between KFS, cerebellar teratoma, and DS has not yet been described in the literature, with only the association of the first two being extremely rare.