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Cardiovascular system

Cardiovascular system

Cardiovascular system

Cardiovascular system




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USMLE® Step 1 questions

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High Yield Notes

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USMLE® Step 1 style questions USMLE

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A 52-year-old man comes to the clinic due to fatigue, joint pain, and recent appearance of skin lesions on his legs. His medical history is noncontributory except for a car accident as a child which required hospitalization and multiple blood transfusions. He has not seen a physician in more than 10 years. The patient does not use tobacco, alcohol or illicit drugs. He is monogamous with one sexual partner. Temperature is 37.0°C (98.6°F), pulse is 75/min, and blood pressure is 130/85 mmHg. Physical exam shows purpuric papules covering the lower extremities that do not blanch with pressure. The rest of the physical examination is unremarkable. Laboratory tests are obtained and shown below:  

 Laboratory value  Result 
 Hemoglobin   15 g/dL 
 Leukocyte count   7,000/mm3 
 Platelets    250,000/mm3 
 ALT  110 U/L 
 AST  75 U/L 
 Rheumatoid factor   Positive   
 Antinuclear antibodies  Negative  
 Urinalysis is unremarkable. Serum protein electrophoresis and immunofixation reveals polyclonal IgG and monoclonal IgM bands. Testing for cryoglobulins shows no precipitation after 24 hours. Which of the following tests is most likely to reveal this patient's underlying condition?  

External References

First Aid








Churg-Strauss syndrome p. 322

autoantibody p. 113

as granulomatous disease p. NaN

labs/findings p. 721


With vasculitis, you have “inflammation”, of the “blood vessels”, and even though this can happen in arteries or veins, we’re going to focus on vasculitis in arteries because it’s way more common.

Vasculitides—plural for vasculitis—are categorized by the size of the blood vessels they affect, so we have small-vessel, medium-vessel, and large-vessel vasculitis.

Typically vasculitis is due to an autoimmune disease, where the immune system confuses a part of normal body as a foreign invader, and there are a couple of ways this might happen.

Sometimes the body confuses the innermost layer of the blood vessel, which is the endothelial layer, with a foreign pathogen and directly attacks it.

To be a little bit more specific, the white blood cells of the immune system mix up the normal antigens on the endothelial cells with the antigens of foreign invaders like bacteria simply because they look similar—and this is called molecular mimicry.

This autoimmune confusion is thought to be the cause several types of medium-vessel and large-vessel vasculitides.

Other times the immune system attacks healthy cells that are near the vascular endothelium, and the endothelial cells are only getting indirectly damaged.

This is the situation in many small-vessel vasculitides, where the immune system attacks white blood cell enzymes or other non-endothelial cell targets.

Once the endothelium is damaged either directly or indirectly, almost all vasculitis diseases progress in a similar way.

The damaged endothelium exposes the underlying collagen and tissue factor, and these exposed materials increase the chance of blood coagulation.

The blood vessel walls themselves get weaker as they’re more damaged, making aneurysms more likely.

And finally as the vessel wall heals, it becomes harder and stiffer because fibrin is deposited into the vessel walls as part of the healing process.

And actually, that’s vasculitis in a nutshell.


Vasculitis is a condition in which there is inflammation of the blood vessels, typically caused by immune-mediated damage to the endothelial cells. The inflammation can affect blood vessels of different sizes, ranging from small capillaries to larger arteries and veins. There are many different types of vasculitis, which can affect various parts of the body, including the skin, joints, and internal organs.

Symptoms may include fever, fatigue, weight loss, joint pain, skin rashes, and organ dysfunction, depending on the type and location of the vasculitis. Treatment for vasculitis may involve medications to suppress the immune system and reduce inflammation, such as corticosteroids.


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