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all right we're gonna cover a big topic
today virally mediated skin lesions
let's get started as we always do with a
case an 11 year old healthy girl
presents with a rash
her mother states that she's noticed a
crop of round bumps appearing on her
trunk and her thighs over the past
several days and particularly in the
groin and inner armpits the mother
appears more distressed about them than
the daughter who reports that they
aren't bothering her at all the patient
denies any fevers chills myalgias
arthralgias URI symptoms or GI symptoms
the only thing is that some of the
lesions are very mildly itchy social and
family history non-contributory review
of systems as we've discussed is totally
negative and her vital signs are
completely normal what we see on exam is
numerous subsets Dimitar skin colored
dome-shaped papules scattered on her
torso we can see some here in the
picture on the right they're also in the
axilla the crural folds the proximal
thighs the lesions are very shiny in
appearance umbilical and their firm
sparing the palms and the soles
importantly there's no evidence of any
mucosal lesions so let's look at a few
key points here highlighting some
prominent variables number one they
sound acute they've just been coming on
over the past couple days secondly the
pattern of skin involvement they're
located on her trunk and her thighs and
rather asymmetrically distributed skin
inflammation the fact that they're non
tender they're not any pustules it
doesn't sound like there's any skin
inflammation and there really is no
evidence of any skin involvement or
systemic involvement based on a
comprehensive review of systems all
right so let's take a look at our
differential diagnosis for this case
first up Corrado ache and filmer now
right away can thelma's are indeed often
described as dome-shaped firm papules
well there's one right there and it does
kind of look like what she has and they
are asymptomatic which is also similar
to what she has but they don't appear in
crops as they did in our patient they
are isolated
lesions with a central character you'd
hope us never see one in an 11-year old
girl
it's a disease of folks over the age of
50 it represents a type of very
low-grade malignancy sometimes called a
pseudo cancer now in defense of its
appearance in this section on viral
diseases of the skin I would be remiss
if I did not also mention that it is
strongly associated with HPV so it's a
reasonable thing to have in this topic
but it's definitely not what she has
so let's exit out next up varicella also
known as chickenpox well it's one of the
many viruses that can cause a so called
viral eggs anthem dozens of viruses can
do this now the lesions of chickenpox
can come on fairly quickly just like our
patient did over several days and they
might indeed look like round dome shaped
lesions but the lesions of chickenpox
are actually fluid filled vesicles
rather than these firm papules and
varicella like most viral exams is
accompanied by symptoms fevers malaise
myalgias headaches perhaps even a sore
throat I had it when I was 19 it was
terrible
now less commonly viral exam things
could have diarrhea lymph adenopathy
maybe even splenomegaly or hepatomegaly
either way it doesn't sound like what
she's got varicella lesions often
transition from vesicles to pustules
after a few days and ultimately will
crust over and resolve spontaneously in
less than 10 days just rounding out the
discussion about varicella so I think we
can safely take it off of our list for
now molluscum contagiosum now this rash
which is also caused by a virus the
molluscum contagiosum virus is
relatively common in children the
lesions of molluscum contagiosum are
described as dome-shaped papules
randomly distributed on the torso and
extremities in an asymptomatic host it
looks like we'll need to keep this one
on the list for now those lesions do
look familiar
next up measles okay this is yet another
virus that causes a viral exam demand
like varicella it's typically
accompanied by a viral pro
with fevers malaise cough conjunctivitis
is common and sinus congestion now the
lesions themselves are typically diffuse
erythema TISS maculopapular often
referred to as more billa form because
many other viruses look the same as
measles they're only a few millimeters
in size shown here in the top right
picture and they typically start on the
face spreading caudally with areas of
confluence often on the chest and the
neck shown here on the bottom right is a
reminder that measles is also associated
with classic mucosal lesions called Kop
lick spots and you'll definitely see
these referenced on the boards they are
grayish white flat macules on an
erythema de space seen on the buccal
mucosa adjacent to the molars as shown
here now
our patient had firm dome-shaped papules
no mucosal lesions not to mention she
was completely asymptomatic so I think
we can definitely take this one off of
our list lastly let's talk about
erythema multiforme remember while we
often think of erythema multiforme along
with stevens-johnson syndrome and toxic
epidermal necrolysis associated with
drug reactions keep in mind that 90% of
erythema multiforme eruptions are
actually due to infections most notably
HSV and then michael plasma would be
second in place let's take a look at the
next slide to review erythema multiforme
in some more detail so here's some
pictures shown in the right of classic
erythema multiforme manifestations it is
an acute immune mediated eruption with
targeted shaped lesions depicted here
it's really going to afflict young
adults predominantly under age 30
oftentimes under age 10 90% of them as I
mentioned are caused by infections like
HSV and mycoplasma less than 10 percent
of the time it's caused by drugs as
we'll see in some other lecture talking
about SJS and toxic epidermal necrolysis
that ratio is flipped with a small
number causing caused by infections and
a much larger number caused by
medications what you'll see here on the
right are these target I'd erythema
dispatch Buell's that are symmetrically
distributed on the hands and the face
with a centripetal spread towards the
tor
so and you can note here the central
clearing on some of those lesions as a
quick aside sometimes I have trouble
remembering what centripetal versus
centrifugal means always remember
centrifugal has F ug and that makes me
think of a fugitive what are fugitives
doing they're running away
so centrifugal means spreading away from
the body as opposed to centripetal is
running towards the body or coming
towards the body for us to remember that
there are two subtypes of erythema
multiforme the minor and the major
subtype the minor subtype is basically
characterized by just the rash alone
whereas the major subtype is more like a
stevens-johnson syndrome type of picture
with mucosal involvement malaise
myalgias fevers other constitutional
symptoms and it's much more significant
of course our patient clearly if
anything would be looking like a minor
variant here the way that it's managed
if it's mediated or caused by herpes
simplex virus you're going to want to
treat that with draw whatever color
medications could be playing a role and
you may need to add on systemic
glucocorticoids generally just for the
major subtype of erythema multiforme so
having reviewed erythema multiforme I
think we can safely take it off our list
as the lesions are wholly inconsistent
with our patients dome-shaped skin
colored papules alright so it looks like
we're left with molluscum contagiosum so
let's revisit the case and highlight
some key points all right so molluscum
contagiosum is very common in children
and the immunocompromised and our 11
year old healthy girl would be a perfect
case of somebody getting lost
competizione
the lesions here the round bumps
appearing on her trunk and thighs over
the past several days particularly the
groin and the armpits this is a classic
presentation as well molluscum
contagiosum lesions are asymmetric
they've a predilection for flexural
creases and they spare the palms the
soles and there should not be any
mucosal involvement next up as we've
highlighted countless times over the
past few minutes patients should be
asymptomatic they shouldn't be
manifesting with a classic viral
syndrome of myalgias and fevers that
sort of thing
next up the lesions as we've said are
dome-shaped papules with this
characterized central umbilical it'll
bit of a hollowing out in the center of
the lesion and there non-tender
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