BackgroundThe classic Lemierre’s syndrome refers to a septic thrombosis of the internal jugular vein, usually caused by a Fusobacterium necrophorum infection starting in the oral cavity, and typically complicated by pulmonary emboli. However, unusual forms of the disorder have been rarely reported.Case presentationWe describe an unusual case of a previously healthy 58-year-old male with Lemierre’s syndrome, manifesting with lumbar pain and fever. A thrombosis of the iliac veins and abscesses in the right iliac and the left psoas muscles was diagnosed by a computed tomography scan, together with a right lung pneumonia complicated by pleural effusion and an L4-L5 spondylodiscitis. Blood culture and pus drainage were positive for Fusobacterium nucleatum and an atypical Lemierre’s syndrome was suspected. The patient was treated with anticoagulant therapy for 12 weeks and intravenous antibiotic therapy for 6 weeks with a good evolution and resolution of the thrombosis.ConclusionsThis case illustrates the thrombogenic and thromboembolic tendency of Fusobacterium nucleatum and its potential invasiveness, regardless of the site of primary infection. The concept of an atypical Lemierre’s syndrome is redefined here to take into consideration non-cervical sites.