摘要Rationale: Thrombosis of the internal jugular vein is an infrequent and underdiagnosed pathology due to the absence of symptoms. If present, the symptoms are frequently manifested as a sensation of pain and cervical tension. Its etiology is variable, including trauma, central catheterization, and hypercoagulable states, among others. Patient's Concern: A 41-year-old female, previously healthy, was admitted to the emergency room for worsening pain in the left cervical area of 5 d. Previously, she was treated for suspected acute pharyngotonsillitis yet without improvement.Diagnosis: Physical examination revealed a 2 cm in length cervical mass of hard consistency that was painful on palpation and non-fluctuating. Ultrasound study showed thrombosis of the left internal jugular vein. A computed tomography scan revealed that the thrombosis occurred at the cervical portion of the left internal jugular vein as well as the left transverse sinus. Interventions: Hospital admission and treatment with low molecular weight heparin at a dose of 1.5 mg/kg every 24 h. Outcomes: The patient was discharged after 3 d of treatment with vitamin K antagonists. Lessons: Venous thrombosis at the level of the internal jugular vein is an infrequent entity. Clinical suspicion is necessary for the diagnosis given the possibility of absence of symptoms.