Case Presentation: A 59-year-old man with no significant past medical history presented with 3-5 days of left-sided neck pain and swelling. Physical exam was notable for enlargement of the left side of his neck that was tender to palpation. He had no fever, dental carries, pharyngeal erythema, cervical nor supraclavicular lymphadenopathy. His laboratory analysis was notable for a white blood cell count of 9,400/µL. A CT of the neck showed left internal jugular vein thrombosis with surrounding inflammation suggestive of septic thrombophlebitis, also known as Lemierre’s syndrome. The patient was admitted to the hospital and started on IV antibiotics. Due to his lack of typical signs of infection, there was concern for spontaneous and, particularly malignancy-associated, thrombosis. He was also found to have a non-occlusive thrombosis in his opposite subclavian vein and an elevated CA 19-9. The patient was discharged on anticoagulation and IV antibiotics. Despite this, he returned to a different hospital 2 weeks later with a pulmonary embolism. Due to concern for occult malignancy, the patient was referred to oncology, and a PET-CT revealed multiple hypermetabolic lymph nodes without pancreatic involvement. A cervical lymph node excision was ultimately revealing for metastatic germ cell malignancy.

Discussion: Spontaneous internal jugular vein thrombosis (IJVT) is rare, occurring in less than 1 in 25,000 individuals annually. It is most commonly associated with use of central venous access devices (CVADs), but can also be caused by deep neck infections, intravenous drug abuse, trauma, or hypercoagulability associated with malignancy.  Lemierre’s syndrome is rare, with the incidence estimated to be 1 per 1,000,000, and is most commonly caused by a peritonsillar or tonsillar infection with anaerobic bacteria. 83% of cases present with fever and sore throat, and 78% have leukocytosis. On the other hand, malignancy in general has a much higher incidence than Lemierre’s syndrome, with testicular cancer alone having an incidence of 4.84 per 100,000. Malignancy increases the risk of VTE, with a 400% increase in risk of DVT or PE. In isolated spontaneous IJVT, up to 10.8% of cases will be diagnosed with a malignancy within one year.  Our decision for anticoagulation in this patient as part of treatment for a suspected septic thrombophlebitis or Lemierre’s was controversial, as was our decision to pursue further hypercoagulability work-up; however, due his atypical presentation of a rather rare disease (Lemierre’s), our concern for malignancy-associated hypercoagulability led us to place this patient on anticoagulation and ultimately down a path of the definitive diagnosis and treatment

Conclusions: In cases of IJVT without evidence of CVADs, IV drug use, trauma or infection, screening for malignancy should be considered to provide an accurate diagnosis and timely treatment.