In this case, the primary infection was controlled on hospital day 5, as proven by CT evaluation and decreased WBC and PCT levels. The sudden increase in WBC count and decrease in SpO on hospital day 6 were considered to be caused by newly formed septic pulmonary emboli. Pulmonary emboli above the subsegmental level are a possible, but rare complication of LS, and three days were required for diagnosis of LS. As a result, anticoagulation therapy was not initiated until hospital day 8. The WBC count maintained its peak value on hospital days 6–8 before anticoagulation therapy was initiated, but rapidly decreased after initiation. This quick response suggests that anticoagulation therapy may have contributed to the infection resolution achieved by antimicrobials.
In a review of 137 cases of LS, the authors found that 4–6 weeks of carbapenem or piperacillin/tazobactam combined with metronidazole were effective in terms of infection control, but the reason for the choice of such a duration was not explained in any of the included papers . Our antimicrobial treatment was maintained until the WBC counts remained normal for one week and clinical symptoms improved. The duration was 24 days in total and 16 days after anticoagulation therapy proceeded, which is much shorter than the average. However, it is still unknown whether anticoagulation therapy is essential, which is an important issue especially in cases, such as the one we described, that are complicated by large intraluminal emboli.
In the past few decades, evidence remained poor regarding the management of LS, particularly regarding its potentially life-threatening thromboembolic complications. Consequently, physicians must make their decisions based on small case series or anecdotal cases when facing uncommon thromboembolic conditions, such as LS. Physicians who are opposed to anticoagulant treatment confirm that the thrombus is caused by an infection process and will be resolved at the same time when the infection is resolved. In contrast, some authors confirm that anticoagulant therapy may reduce the morbidity and mortality of serious complications, such as cavernous sinus thrombosis or pulmonary embolism. Theoretically, a septic thrombus sequesters bacteria and creates a barrier to antibiotic penetration. When the thrombus is dissolved by anticoagulants, the bacteria are exposed to a higher concentration of antibiotics, increasing accessibility . Our case supports this hypothesis precisely. Unfortunately, randomized controlled trials are impractical to investigate the use of anticoagulation therapy in the treatment of LS due to the rarity of this illness. Based on small case series, the proposal has been advanced to reserve this approach to bilateral disease only; a single-center retrospective series has found no association with thrombus recanalization, although it is unclear whether recanalization is clinically relevant . The improvement seen in our case despite the absence of bilateral disease and the finding of recanalization following anticoagulation could be explained by the likelihood that the thrombus had developed recently, as suggested by the sudden increase in infection parameters, and may have been more vulnerable to anticoagulation than an older, organized thrombus. This possibility is consistent with the known biology of venous thrombi  and should be explored by future research.
A recent European collaborative study performed an individual patient-level analysis of 712 cases published globally from 2000 to 2017 . The authors could not find disease-specific elements against the safety of anticoagulation and drew the conclusion that therapeutic anticoagulation is indicated for LS if there are no contraindications. Nevertheless, the authors did not provide definitive guidelines for the duration of anticoagulation. According to the American College of Chest Physicians guidelines for provoked thrombotic events, anticoagulation therapy is recommended for a duration of at least 3 months , which may be available for reference to Lemierre syndrome presented pulmonary embolism. Our patient received a treatment duration of 20 weeks because his follow-up visit was delayed by the outbreak of COVID-19. A limitation of our case is the lack of microbial isolation. However, the diagnosis of LS is currently accepted even without microbial isolation in the presence of a clinical diagnosis of sepsis from an oropharyngeal focus and thrombi or emboli consistent with the primary infection location .
In conclusion, therapeutic anticoagulation may be considered in the management of LS, while further research is needed to evaluate whether the use of anticoagulant and antibiotics leads to better clinical outcomes than the use of antibiotics alone.
I’m the daughter of the patient. We are grateful to the doctors’ help in Changzhou First People’s Hospital and happy to share the treatment experience of my father.