From Mouth to Knee in HHT: An Unusual Complication of Hereditary Hemorrhagic Telangiectasia

Introduction: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder affecting blood vessels that results in mucocutaneous telangiectasias and AVMs. Patients with pulmonary AVMs are at risk for extra-cerebral infections such as septic arthritis. This is a case of a 28-year-old female, with a history of nosebleeds, who presented with right thigh pain, tachycardia, and epistaxis who was found to have septic arthritis secondary to oral flora in the setting of newly diagnosed HHT.

Case Description: On initial presentation, CT angiography is obtained and returns negative for pulmonary embolus but demonstrates 3 large pulmonary arteriovenous malformations (AVMs), concerning for a new diagnosis of HHT. During admission, she becomes increasingly hypoxic, febrile, and develops a swollen right knee. Joint aspiration of the right knee returns frank pus. She is started on parental antibiotics and taken to the operating room for irrigation and debridement. In the setting of ongoing fever, knee pain, and elevated inflammatory markers, CT imaging of her right lower extremity is performed which shows recurrent large abscesses in the popliteal and thigh compartments prompting numerous repeated surgical debridements. Surgical cultures from these operations grow multiple oropharyngeal flora including Campylobacter rectus, Eubacterium brachy, Prevotella oris, Parvimonas micra, and Strep anginosus. Additional infectious workup including echocardiogram, formal dental evaluation, and CT imaging shows no evidence of infectious foci nor other AVMs. During her hospitalization, there are extensive discussions regarding timing of embolization of pulmonary AVMs, which is deferred in setting of persistent bacteremia. Unfortunately, she ultimately requires an above-the-knee amputation of her right lower extremity due to recurrent infection. Three months later, she undergoes embolization of her pulmonary AVMs.

Discussion: This patient’s polymicrobial septic arthritis of a native knee joint represents an unusual presentation of a common autosomal dominant genetic disorder presenting in adulthood. It was proposed that the presence of her pulmonary AVMs allowed paradoxical embolization of normal oropharyngeal flora from transient bacteremia to seed her knee as the bacteria bypass the normal pulmonary capillary beds that would typically filter these pathogens out. Review of the literature was significant for a handful of case reports detailing brain abscesses from oropharyngeal flora, but no cases discussing septic arthritis. Upon further questioning, it was discovered that her father also had HHT. According to the 2020 International Consensus Guidelines, her case warranted further investigation which likely would have resulted in therapeutic embolization of her pulmonary AVMs much earlier in life.

Conclusion: This case highlights the importance of appropriately assessing family history and understanding the screening and referral process in patients with known first degree relatives with HHT. It also demonstrates the importance of understanding that transient bacteremia alone without a primary source can cause remote infection in patients with mechanisms to facilitate paradoxical emboli.