A 33 year old female presents to the clinic for evaluation
of yellowish discoloration of her skin and eyes.
She has had this problem for the past 6 months but
states that it is getting worse over the past few weeks.
She also complains of repeated bouts of bloody diarrhea and
abdominal pain that had been very embarassing for her.
On examination, her blood pressure is 110/60 mmHg, pulse
is 90, respirations are 19 and her temperature is 36.6
Her abdomen is soft with no
tenderness or rebound tenderness
but the rectal examination shows
blood and mucus in the rectal vault.
Her sclera appear yellow along
with the face and upper body.
Laboratory results are
obtained and below:
AST - 170 (U/L), ALT - 250 (U/L), ALP - 120 (U/L),
sodium -140 (mEq/L), and potassium - 3.8 (mEq/L)
Which of the following antibodies would
you expect to find in this patient?
Answer choice (A) -
Answer choice (B)
Answer choice (C) - p-ANCA
Answer choice (D) - anti-CCP
and answer choice (E) -
anti-double stranded DNA
Now take a moment to come your
own answer for this question.
Okay let's tackle this
Now this question is going to be a pathology question.
and given the fact that we're looking at liver enzymes,
AlkPhosph, jaundice - this is going to be a GI question.
Now this is a 2-step question.
First we need to determine
the diagnosis and second,
we need to determine the antibodies
associated with the diagnosis.
Now, the stem is very much required in this case to provide a
clinical history to aid us in the diagnosis in this patient.
So let's start with step 1-
let's determine the diagnosis.
Now this patient's clinical presentation of bloody
diarrhea, abdominal pain, combined with jaundice
is suggestive of a generalized
Now the differential diagnosis here
includes inflammatory bowel disease
of which we are considering Crohn's and
ulcerative colitis, malignancy and GI infection.
Now for this patient, malignancy seems unlikely given the
absence of B symptoms such as weight loss or nights sweats
and also the patient's young
age of being 33 years old.
Patients with rectal and colon
cancer tend to be older in age.
Now infection also seems to be unlikely
given the absence of a mention of fever
and the patient's long duration
of symptoms of 6 months.
Now that leaves inflammatory bowel disease, Crohns and
all sorts of colitis at the top of our differential.
Now if you refer to our image, we can see
that each disease has distinctive features.
Now on our left we see a condition
depicted as Crohn's disease
and on our right we have the
condition for ulcerative colitis.
Now Crohn's disease as we can see here affects
the entire GI tract and commonly has skip segments.
Now with Crohns, we often have extraintestinal
symptoms such as lesions of the skin and to the mouth
but easy to remember that as ulcerative
colitis has the word 'colitis' in it,
and this tells you that it
is limited to the colon.
So in comparison, Crohn's disease can have
skip lesions affecting extraintestinal sites
but our next condition that we see on the right,
ulcerative colitis has the word 'colitis' in it
really telling you it's limited to the colon.
So then, ulcerative colitis affects the large bowel
or the colon and does not produce skip segments
and does not have
Now, given this patient's presentation, it sounds
most likely the patient has ulcerative colitis
and this is supported by the jaundice as well.
And this patient is likely suffering from ulcerative
colitis with associated primary sclerosing cholangitis.
Now that we know the diagnosis for this patient, let us
go back to the image to review some of more distinctions,
to really reinforce them as it is extremely
high-yield to understand the distinction
between Crohn's disease and ulcerative colitis.
Now looking at the left, we see that we have ASCA IgG
and IgA, antibodies associated with Crohn's disease
and now we can see the whole GI tract is
affected, it is discontinuous with skip segments
and you have what is called transmural inflammation meaning the
inflammation goes all the way down through the actual GI system
not just in a mucosal level or superficially but we're
gonna go all the way down to our basement membrane.
And of course, we have extraintestinal manifestations of
we can have skin, eyes and also colorectal malignancy.
Now looking at the right, we have ulcerative colitis,
with associated p-ANCA as the diagnostic marker
and this, with the word colitis affects only the large bowel,
and it is continuous in the large bowel and it is superficial
- not transmural like Crohn's disease,
only superficial mucosal inflammation
with some extraintestinal manifestation and
also a risk for colorectal malignancy.
Now let's look at step 2.
Now that we know the diagnosis in this case as
most likely ulcerative colitis with associated
primary sclerosing cholangitis,we need to know
what antibody is associated with this condition.
Now for these patients, most of them will test
positive for p-ANCA - very important to know.
Now in this case thus the
answer is answer choice (C)
- perinuclear anti-neutrophil cytoplasmic
antibodies or most commonly known as p-ANCA.
Now let's discuss some high-yield
facts for inflammatory bowel disease.
Now inflammatory bowel disease really is just a description
of a group of inflammatory disorders that affect the GI tract.
The most important and notable for students taking USMLE
step 1 are ulcerative colitis and Crohn's disease.
Now ulcerative colitis affects
continuous segments of the GI system
but it is most common in the rectum and
descending colon - very high yield.
Now Crohn's disease generally affects
intermittent or skip segments of the GI system
and is often diagnosed based
on findings in the mouth.
Now common symptoms include: bloody
diarrhea, abdominal bloating and pain
which you may see in the clinical
vignette on the question on real exam day.
Now the treatment here can be surgical, as you can have
a proctocolectomy in the case of ulcerative colitis
or medical with immunosuppression although full care
and full cure with medical therapy is uncommmon.