Lemierre Syndrome: A Rare Complication of Infectious Mononucleosis.

Lemierre syndrome is a rare condition that arises from septic thrombophlebitis most commonly in the internal jugular vein. Common precipitating factors include recent oropharyngeal, tonsillar, or dental infection or chronic bacteremia. While modern antibiotic usage has decreased mortality rates, challenges persist in accurately diagnosing the condition at the time of patient presentation due to a lack of awareness of this rare disorder. Here, we present the case of a previously healthy 20-year-old female patient who was diagnosed with infectious mononucleosis approximately two weeks before her hospital admission. She presented with a five-day history of shortness of breath and cough. Diagnostic workup/evaluation revealed pneumonia with bilateral pleural effusions as well as the need for intravenous antibiotics and oxygen via nasal cannula, prompting her admission to the hospital. During her hospitalization, blood cultures showed growth in two out of four test tubes with Streptococcus intermedius, a bacterium commonly associated with abscess formation. This finding led her medical team to conduct a computed tomography scan of her cervical region, revealing significant septic thrombophlebitis within her internal jugular vein.