Vasculitis: Pathology review

At the clinic, two very different people with very different symptoms showed up. Novakova is a 60 year old woman from Czech Republic who’s been having a headache by the right temple, progressive jaw pain during chewing, and shoulder and hip stiffness, particularly in the morning. Her ESR levels are elevated, and she is beginning to develop vision loss in the right eye. The other person is Hikaru, a cute 3-year-old Japanese boy brought by his mother. He has a red, swollen tongue, unilateral neck swelling, a desquamating rash, and a fever for the past 6 days. An ECG reveals elevation of the ST segment, and an echocardiogram shows evidence of a coronary artery aneurysm.

At first glance, you’d think Novakova and Hikaru symptoms have nothing in common. But the fact is, they both have different forms of vasculitis. The majority of vasculitides are caused by some form of immune-mediated damage. Some are type III hypersensitivities caused by immune complexes that deposit in vessels and cause damage. They could also be triggered by autoantibodies, like anti-neutrophil cytoplasmic antibodies, or ANCA. Lastly, they might be caused by cell-mediated immunity due to monocytes, macrophages or lymphocytes.

Whatever the cause, immune cells cause inflammation, which damages the endothelial wall, exposing the underlying collagen. This results in thrombosis and could lead to ischemia of the organs supplied by the affected vessels. Also, inflammation weakens the structural integrity of the blood vessel wall, leading to aneurysms. In addition, inflammation can spread to the supplied organ itself, causing tissue damage.

Since vasculitides are systemic inflammatory disorders, non-specific symptoms like fever, arthritis, myalgia, weight loss, and night sweats might be present. The symptoms specific to each disease depends on which blood vessels are affected, and we can classify vasculitides into large, medium, and small-vessel vasculitis.

For large vessel vasculitis, let’s start big, with temporal, or giant cell arteritis. Age is the greatest risk factor, and it typically affects people older than 50 years. It's also more common in females of Northern European descent. Giant cell arteritis affects the branches of the carotid artery like the temporal artery. For your exams, remember the person with this disorder often complains of having an unilateral headache located in the temporal area. They might also have fatigue or pain during chewing, or jaw claudication, which is caused by ischemia of the masseter muscle.