All right. Having talked about the
non-immune mediated types,
we're going to cover some of the
immune-mediated types. In fact,
the vast majority of acute
cutaneous drug reactions are
and they can cause nearly
every type of skin manifestation you've
ever heard of including, urticaria,
papules, pustules, bullae, lichenoid lesions,
lupus-like illness, etc. We'll just go
through a few of these examples.
First up, we have to cover
These are the most common type
of the most common type
of cutaneous drug reaction. 90% of
all cutaneous drug reactions
The most classic presentation is so-called
"morbilliform" eruption, which means
that it looks like measles.
It's going to be on the trunk, the extremities,
it tends to be symmetric in
distribution, though there may be some areas
of confluence. It's going to resolve
typically spontaneously once you
get rid of the drug,
though there will be this
phase as some of the superficial
skin sloughs off.
Most importantly, these patients have
minimal systemic symptoms,
and that's a defining feature
of the reaction.
Culprit drugs, you know a lot of them.
Typically, it's antibiotics.
Sulfa drugs, beta-lactams like penicillin,
anticonvulsants can do this, and allopurinol
can cause a variety of different
skin reactions, and this is another one of
them. NSAIDs also maybe a culprit.
The typical rash that you're seeing here
is pruritic, and you'll have these
bright red macules and papules.
Exanthematous reactions are more
common in those who have
recently contracted EBV or CMV,
and in those who have HIV.
The typical onset is
1-21 days after starting the new medication,
and that's typically dependent on whether
they've seen the medication before
or if it's a brand new medication
to them. Oftentimes, it will
occur as I'm alluding to within only
2-3 days if it's a re-exposure
to something that they've already
developed antibodies to. Importantly,
I said that patients should not
experience systemic symptoms.
If you do start to see some of those
systemic features -- myalgias,
fevers, mucocutaneous involvement -- then you've
got to start thinking about SJS and TEN.
If it is just an exanthematous
reaction, you can get
by with just using anti-histamines,
perhaps glucocorticoids under