00:01
So then,
how do we distinguish
between melanoma
and a benign melanocytic nevus?
Of course, a benign melanocytic nevus,
commonly known as a mole
is something that almost everybody has,
some number of moles.
00:14
How do we tell the difference
between that and a very severe
aggressive skin cancer
like melanoma?
Well, there's this commonly used
very simple acronym ABCD
which is one way to think about
the differences that we should look for
in the particular features
that would lead us towards melanoma.
00:32
In the top row here are pictures
of melanoma of different types
and the bottom row are
benign melanocytic nevi.
00:40
They're called compound melanocytic nevi
if they are exophytic
again, growing off of the skin
as opposed to a flat macule.
00:47
Looking at the
first column there
on the top,
we have evidence of asymmetry.
00:52
This is a lesion which has
a lot of asymmetry.
00:54
It's not the same on one side
as it is on the other.
00:57
If you look at the lesion underneath it,
that's a benign lesion
and you can see it's pretty much symmetric
from one side to the other.
01:04
The second one would be
irregular borders
and that second column certainly has
dramatically irregular borders
compared with
the one underneath it
which is almost
a perfect circle.
01:16
The third one would be
color variation
and you can see
in that third column
you've got some reddish,
then violaceous
then brownish black
kind of discoloration in that lesion
compared with a homogenous uniform color
in the mole underneath it
Lastly, diameter,
the size of a lesion
and it's not just the size of the lesion
at one point in time
it's how much is that lesion
growing over time.
01:38
If it's expanding rapidly
over a matter of a few months
you're going to be much more concerned
about an aggressive melanoma.
01:48
There are actually four different
subtypes of melanoma.
01:51
The most common of which,
about 70% of cases
is called superficial
spreading melanoma
and that's depicted here
on the top left.
01:59
Importantly,
superficial spreading melanoma
as melanoma goes,
it's the best one you could get.
02:04
Since it is fairly superficial,
it can be readily removed.
02:08
It's the most treatable of all
the different types of melanoma.
02:12
The second most common
is called the nodular type.
02:15
The bad news of a
nodular subtype of melanoma
is that it is penetrating
and growing deep
or vertically
rather than horizontally
and so it tends to penetrate from
the epidermis into the dermis more readily
and you're more likely to have either
local or distant metastasis.
02:32
The third type, less common,
is lentigo maligna.
02:40
It starts off as a brownish
discoloration of the skin
and then can gradually evolve
into more aggressive lesions.
02:46
It's common in the elderly,
most commonly seen on the face
and it is one of the lesser known
subtypes of melanoma.
02:54
Lastly,
acral lentiginous melanoma.
02:57
These ones are atypical
because all the other ones
are going to occur
in sun-exposed areas
but acral lentiginous melanoma tends
to occur on the palms of the hands
or the soles of the feet
or even underneath the nail plates.
03:14
Looking at our patient’s image,
again, very irregular borders
we have the
asymmetric features
we have color that is very
heterogenous in appearance.
03:23
This is very concerning
for a malignant melanoma
and she's definitely going
to need a biopsy.
03:30
Let's look back at our case again
and reflect on some of the features
that may guide us towards melanoma
or towards some other lesion.
03:37
We know that her age,
as she gets older
makes it more likely
to have a malignant lesion.
03:43
That being said,
superficial spreading melanoma
is relatively common
in younger men and women
especially those who had
significant sun exposure.
03:54
Sometimes,
there's a preceding mole
and the melanoma begins
to grow within the mole.
03:59
But oftentimes, it may start de novo,
so that's something to be mindful of.
04:03
Importantly,
her lesion was itchy.
04:05
Now, you may not normally
think of a skin cancer as itchy.
04:09
But if you do see evidence of itchiness
or perhaps even pain
that may suggest that
there is dermal invasion
and that the tumor has now gone
beneath the epidermis into the dermis
and now it's
penetrating and involving
some of the nerve endings
embedded in the skin.
04:25
So, that may be
a concerning finding.
04:28
Next up, our most common
risk factors are the sun.
04:32
Folks who've had a history of
severe sunburns as a child
where there was blistering
and a significant pain, that's a concern
or just chronic sun exposure,
folks who work outside
in this case,
our patient is an avid tennis player
so she's getting
a lot of sun exposure
especially if she's not lathering up
with sunscreen on a regular basis.
04:51
Of course, patients who are fair-complexioned
are more susceptible.
04:54
Skin cancers in general are relatively rare
amongst dark-skinned patients.
05:00
Their dark skin,
their hyperpigmentation, is protective.
05:05
Then again,
we've got the ABCD picture here.
05:08
As I mentioned,
the asymmetry of the lesion
the borders that are irregular,
the color changing, and the diameter.
05:14
This is a four centimeter
hyperpigmented macule.
05:17
That's going to steer you
towards thinking about melanoma.
05:22
In terms of prognosis and management,
a tumor that's confined to the skin
you're just going to basically
use surgical excision
and looking for clean margins.
05:32
This is an approach called
Mohs surgery
named after a guy named
Frederick Mohs in the 1930s.
05:38
Essentially, it's where the surgeon
excises a very small sliver of skin
and then sends that skin
to the lab.
05:46
It's reviewed under microscopy
while the patient is waiting
and you continue to take off
little slivers of skin
until you're sure you have
clear, clean margins.
05:55
Once you've got
clean margins
then you can basically
close the case and move on.
06:02
The likelihood of having lymph
nodes that are involved
is entirely dependent upon
how deep that initial lesion is.
06:10
You're almost always going to assess
the most proximal lymph nodes
to see if there's any evidence
of tumor involvement there.
06:16
That's going to help
with staging.
06:18
The presence of distal metastasis
correlates with initial depth of lesion.
06:23
Once you've got that tumor
penetrating into the dermis
you're very likely to have issues
with proximal nodes involved
or even metastasis
somewhere else in the body.
06:33
The staging system that is
commonly used uses Clark's Levels.
06:37
These are basically a grading
system that looks at
the depth of lesion
and predicts five-year mortality.
06:46
Along the same lines,
like many cancers
they use the TNM staging criteria,
which is the size of the tumor
is there proximal lymph
node involvement
and then is there
any evidence of metastasis.
06:59
In general, melanoma is
a very aggressive skin cancer.
07:03
Patients who have
stage three melanoma
it's almost a
universally fatal diagnosis.
07:10
So very tragic
when diagnosed at that stage.
07:13
There is also
a high rate of relapse
even for those who did have
a good clean margin
from a superficial
spreading tumor.
07:19
You really have
to be very vigilant
about following
these patients over time.