In this lecture, we’re going to discuss lupus, more formally known as systemic lupus erythematosus or SLE.
Lupus has a unique pathology. Basically, this is a multisystem inflammatory autoimmune disease
that’s caused by immune-complex mediated damage. It affects multiple organs in different ways
in different people and the cause is unknown. There are genetic factors, environmental factors,
and hormonal factors which mitigate the disease. It is more common in girls than boys. The peak
pediatric age of diagnosis is 9 to 15 years of age. We don’t usually see it in the very young children.
The pathophysiology of lupus is as we stated both genetic and environmental. In a susceptible
individual who has susceptibility genes, they’re going to have an event that results in apoptosis,
for example, they might get a sunburn on their skin, a UV radiation, a period during which cells
are breaking down on a larger scale. These patients, because of their genetic susceptibility, will have
a defective clearance of these apoptotic bodies resulting in an increased burden of nuclear antigens
throughout the body. In this susceptible person, the B cells and T cells will mount an immune response
against these nuclear antigens. This will create anti-nuclear antibody antigen complexes which will
then go through the body going to stimulate both dendritic cells which then stimulate B cells
and create antibodies vastly against nuclear antigens. These nuclear antigens with antibody complexes
are causing the mainstay of the disease in organs throughout the body. Let’s go through some
of the basic symptoms of SLE or lupus. Constitutionally, these patients get frequent fevers.
They may have fatigue and they’ll develop weight loss as well. Their skin has a few key findings.
This girl has one of them, a malar rash. They may also have a discoid rash which are little round circles
around the skin. Discoid rashes are also common in babies with lupus and we’ll talk about that separately.
Also, patients may get photosensitivity which is an increased susceptibility to burn when exposed
to the sun. Patients do get lung involvement. They can get pleuritis, pleural effusions,
pulmonary hemorrhage, or even pulmonary hypertension. They have cardiac findings.
Additionally, they will have pericarditis, myocarditis, and endocarditis. Any part of the heart
can be involved. They can get cardiovascular or vascular problems such as Raynaud’s phenomenon
which you can see in this patient here where there’s decreased blood flow to the distal end of a digit.
In patients with lupus, they can get an endocarditis that is unique called Libman-Sacks endocarditis.
It looks grossly like bacterial endocarditis but does not grow any organisms on blood culture.
This can appear as single or multiple 1 mm to 3 mm warty deposits on those valves
and you can see a picture of one here. These patients may have involvement of their renal pathways.
They may develop proteinuria or hematuria depending on if they’re having more nephritic
or nephrotic syndrome. They may develop a pyuria from just white blood cells that are inflamed
in the kidney but they will not grow anything on the urine culture. They may develop hypertension
as a result of their end stage renal disease and they may proceed to renal failure. The GI system
can get involved as well and in particular these patients may develop oral ulcers, pancreatitis,
hepatitis, intestinal vasculitis, or even a protein-losing enteropathy. Essentially any part of the GI tract
can be involved. They may have muscle disorders. They may develop arthritis or myositis or
avascular necrosis of a joint. Importantly, they may develop brain problems. Roughly, 10% of patients
with lupus will present with a brain problem. Examples include stroke, psychosis, seizure, chorea
or a tremor. They may develop a transverse myelitis of the spine. Additionally, patients can get
problems with their blood and any bloodline can be affected. They may get lymphopenia, anemia,
or thrombocytopenia. Any cell line on the CBC can go down. This is a lot of stuff. These are a lot
of symptoms to remember. Unfortunately, there’s no gene test for lupus. It’s a clinical diagnosis.
For a diagnosis, you need four or more of the eleven major criteria of lupus. Who can remember
eleven criteria of lupus? Well, you can with a little mnemonic. Here it goes. “M.D., please offer
all RNs a holiday immediately.” Again, “M.D., please offer all RNs a holiday immediately.” You have to do
the S after the RNs. Let’s look at it this way. “M.D., please offer all RNs a holiday immediately.”
What’s clever about this is the last three are lab criteria and the first eight are body, physical
exam criteria. Let’s go through them again so we can remember them. M is the malar rash.
D is the discoid rash. P is the photosensitivity. Those are the skin findings in lupus. O is oral ulcers.
A is arthritis. The R is renal involvement. The N is neurologic involvement. The S is tricky, it’s serositis.
Remember, your serosa are superficial coverings of your organs. The area around the heart is
the pericardium. That is a serosa. So, pericarditis is a serositis. Peritonitis is a serositis.
Pleuritis or a pleural effusion is a serositis. Next, the labs. The ANA test is its own criteria.
The interesting thing about the ANA test is that virtually every patient with lupus will have
a positive ANA. This is the one that almost all of them have that is positive. A positive ANA is necessary
almost for a diagnosis of lupus. If they’re not ANA positive, they will be very soon. The challenge
is that one in three people walking down the street will have a positive ANA. Heck, they’re even
a little bit infectious. By that, I mean if you were ANA negative and you move into the home
of someone who is ANA positive, you’re more likely to become ANA positive. That doesn’t mean
you’re getting lupus. So, the ANA positivity is necessary but not sufficient for the diagnosis.
H is heme labs. Again, back to any of those elements of the CBC. They may have an abnormal
white count, abnormal hemoglobin, or abnormal platelets and all of them are usually low.
I is immune labs and I’ll walk you through what those are in a bit.