Our second case. Now, this is
a 12-year-old tennis player.
Past medical history, again, of dermatitis --
pretty much anything that involves
the skin from a lay audience is called
dermatitis -- presents with an
intensely pruritic rash on her arms
over the last few days.
This is sounding again like atopic
eczema. At baseline, she has
intermittent flares of pruritic,
overlying her antecubital fossa,
volar wrists, bilateral ankles,
for which she uses topical steroids.
Slam dunk case of atopic eczema.
5 days ago, however, she had to go
into the woods behind the
practice courts to retrieve a tennis ball.
Allergic to tree nuts, eczema, atopy.
Father eyes allergic rhinitis,
sister has asthma.
Review of systems, again, is negative. Boring
vitals. Moving on to the skin exam.
Scattered erythematous papules and vesicles,
and small bullae -- a little bit
unusual for eczema --
oozing some yellowish
adherent fluid with crusts.
And you can see the picture there. Looks
like a kind of moist picture rather
than a dry lichenified-type
picture. In this case,
again going to our differential diagnosis,
seb derm doesn't happen on the arms.
Irritant contact dermatitis? I think that
would be our leading guess here
because we're worried that since she
was in the woods, we're worried about
an exposure to urushiol. Again, that's the
oil resin that comes from poison ivy.
And this would be a classic
presentation of that over the
span of a few days.
And we can expect that some new crops
may appear over the next couple days,
simply because the skin may have
been absorbing that
urushiol at different rates. Allergic
screen the patient for other potential
exposures. Doesn't look like psoriasis,
none of the silvery scale, atypical
location. And again, she
clearly has atopic dermatitis, but
this is an acute problem
on a backdrop of some chronic skin disease.
Final diagnosis is clearly
an irritant contact dermatitis
Okay. Now we have a few quick
review questions. I'll ask
a question. Feel free to pause the screen,
so you can reflect on the answer.
What do you remember about irritant
and allergic contact dermatitis,
and in particular, what distinguishes
the 2 of them?
All right. By way of review, let's
take a look at this slide.
The key point here is the
etiology. An allergic
contact dermatitis is caused by a localized
T cell-mediated response to an allergen,
and it's a delayed-type
whereas irritant is a localized
to a physical or a chemical irritant.
There's a direct cytotoxic response
going on in that case.