So let's go revisit polyarteritis
nodosum for a second.
So, again, this is a systemic
of medium-sized arteries in multiple organ
systems, whether it's the skin,
the intestines, the kidneys, etc.
It's idiopathic. We don't
really know what causes pretty much
any of the primary vasculidities,
though it has been often linked
with hepatitis B and
hepatitis C virus, maybe
about 30% of the time.
What we see if we were imaging
arteries, we see it's segmental,
transmural -- that means through the entire
wall of the vessel -- inflammation
that leads to either luminal narrowing,
potentially thrombosis within the vessel
with downstream ischemia, ballooning
aneurisms of the vessel, as we see
in our image here on the right,
and of course, tissue necrosis due
to downstream ischemia. The diagnosis would
be performed by checking a variety
of autoimmune tests.
It is an ANCA negative vasculitis, unlike
a variety of ANCA positive vasculidities.
You typically do require a biopsy,
whether it's a biopsy of
the skin where you might see
leukocytoclastic vasculitis, or a biopsy
of a kidney, for example. And a
slam dunk finding would
be evidence of those aneurisms, those scattered
aneurysms and irregular constrictions
when you performed a mesenteric
or a renal arteriography.
Treatment for polyarteritis nodosa and
for most other vasculidities
is steroids up front, plus or minus
cyclophosphamide. And, of course,
since our patient does have hepatitis B,
we probably would want to
take care of that as well.
Other manifestations of PAN to consider
knowing that we're talking about
arteries that go to multiple
organs in the body,
you may see palpable purpura on the skin,
tender subcutaneous nodules,
which is what we're seeing in our patient. You
may see a pattern of livedo retcularis,
particularly in the lower extremities.
Renal disease with PAN involves renal
artery aneurysms, which can, of
course, lead to downstream ischemia,
renal infarcts and acute kidney injury.
Our patient's creatinine was a
1.4, which may support that. Neurologically,
also talking about the blood supply to
nerves, you can see mononeuritis,
potentially mononeuritis multiplex if multiple
peripheral nerves are involved.
And then from a gastrointestinal standpoint,
you'd be looking for mesenteric ischemia.
So, having spoken about polyarteritis
nodosa for a moment,
I don't want to write off erythema
nodosum yet, so let's take
a little bit of a closer look at E. nodosum.
Erythema nodosum is a delayed
type hypersensitivity reaction
leading to inflammatory
panniculitis, which means
inflammation in the subcutaneous fat,
particularly, of the anterior lower legs,
though it can occur in other
locations as well. It's more common
in younger women,
and there's a variety of different causes,
as we've suggested. Medications,
most commonly sulfas, oral
contraceptive pills, penicillin.
One drug you probably won't find on this
list is the drug that she newly started,
entecavir. So, I'm thinking that
may just be a coincidence.
Infections, streptococcus, tuberculosis,
some fungal infections like
histiocytosis, coccidioidomycosis. A
number of inflammatory conditions
most classically would be sarcoidosis --
particularly with the Lofgren's
subtype of that --
inflammatory bowel disease. Some malignancies
you may see E. nodosum,
pregnancy, and then a third of cases are
actually idiopathic and we never
never find out exactly what precipitated it.
Shown here, is a picture of some tender,
non-ulcerated erythematous nodules.
It's, of course, hard to visualize
tender subcutaneous nodules
since you may not see much
on the skin because it's really palpating
the area and finding that
tender, indurated area that tells
you what's going on there.
The onset can be over several days. It, sort of,
depends on what the etiology is.
And it is often preceded by some
URI symptoms; maybe some fevers,
maybe some arthralgias,
maybe even some coughing, and sore throat.
And it may, of course, depend on what
the particular etiology of our patient's
erythema nodosum is.
A biopsy, if you were to perform it,
would not tell you what caused
the erythema nodosum, but it
would confirm the diagnosis
because you'd find a granulomatous
panniculitis in the skin.
So, we've still got E. nodosum and PAN
on our hands. Let's take a look
back at the case again, and
highlight some key points.
So, again, 52-year-old woman, this
would go more in line with
polyarteritis nodosum, in particular with
the recently acquired hepatitis
B infection, neither one of which would
be seen with erythema nodosum.
The presence of those fevers, arthralgias,
painful bumps, and sub-acute
onset of symptoms, kind of supports
both diagnoses, so it's not going to help
to tease those 2 things apart.
The prandial abdominal pain, however,
exacerbated by eating, again,
that's concerning for mesenteric ischemia,
much more likely to be seen
with polyarteritis nodosa.
But keep in mind, that patients will
have inflammatory bowel disease,
which could also be characterized
by some belly pain,
and even some hemoccult positive stool,
could also lead to erythema nodosum.
o, something to be mindful of.
And then lastly,
the weight loss, the fatigue, the malaise,
all those constitutional symptoms
really can go along with both conditions as
well, so that's not helping to tease apart
our diagnosis. What I think is most
important here is the
absence of the things that would
support E. nodosum. So,
we're not getting a story of sarcoidosis.
We're not getting a story of any of the 2
inflammatory bowel disease types. There's
no new medications or at least no
common culprits. Entecavir would not be
one of the ones we'd think of.
No recent strep infection, no
tuberculosis, etc. All those
things are going to steer us away from EN,
especially when you're looking
at a board review question. There should
be an obvious associated condition
in the history. On physical exam,
the most characteristic features here that
steer one way or the other is
the tender purpuric papules on the calves,
not on the pretibial areas, definitely suggest
more of a polyarteritis nodosum
type picture, and you can imagine that
if we were to biopsy that
area, we'd find a leukocytoclastic
vasculitis. In contrast,
the anterior or pretibial area of the legs
is where we do a biopsy and you'd find
panniculitis supporting erythema nodosum.
So, with that, I think we can safely
say that despite this being the
erythema nodosum video, this looks like
polyarteritis nodosum, instead.
If our patient, however, did have erythema
nodosum, just to round off this topic,
we would, of course, want to identify and
treat the underlying condition. Maybe
it's the beginnings of sarcoidosis, maybe
tuberculosis, a variety of other things.
We want to make sure we try and
find what could be the cause.
Treatment is pretty straightforward. You can
use some NSAIDs for pain control and
using the anti-inflammatory properties
of NSAIDs to cool it down. Steroids
would be a, something you would
use only as needed if they're
particularly painful lesions involved, but
would be reserved for only extreme
cases. And alternatively,
since it's kind of is a self-limiting
probably going to resolve either after
you treat the underlying cause,
or it'll just resolve on its own within weeks
to months. You could just wait it out.