Idiopathic internal jugular vein thrombosis (IJVT) is a rarity that we must quickly identify and manage, as it may have severe consequences such as cerebral venous sinus thrombosis (CVST). CVST might be fatal unless it is managed promptly. However, due to its rarity, clinicians are often unfamiliar with the presentation of this pathology.We report an unusual finding of IJVT in a 53-year-old female patient who presented with a cervical mass on the left side to our otolaryngology outpatient clinic. A cervical ultrasound and computed tomography (CT) confirmed the diagnosis of IJVT. An extensive workout ruled out thrombophilia, CVST, cardiovascular diseases, head and neck cancers, and urinogenital tract neoplasms. The symptoms resolved under treatment with anticoagulation.