Next stop, let's talk about tinea corporis.
Now, tinea corporis, also known as
'ringworm' is a very common fungal infection.
It's caused by a specific group
of fungi called dermatophyes.
They just love to feed on human keratin, you know
from dead skin, nails, hair, that sort of thing.
The risk factors for tinea corporis are diabetes, HIV,
obesity, pets and just moisture or hygiene issues.
Now tinea is a member of the tinea family
which I'm now happy to introduce to you.
Here it is, the tinea family.
Now each of the variants that I'm showing here is
characterized by a slow progression of a pruritic,
scaly rash but each has some unique features.
First off, tinea capitis.
This is actually one of the ones
that's most difficult to treat
It appears of course on the
head, capitis - in the scalp.
It's actually one of the diseases that we
consider a cicatricial cause of alopecia
which means that it can cause
scarring if left untreated.
And you could have a patch of hair
loss that will not grown back.
Tinea pedis, of which there's 2 major types.
There's the moccasin form which
we also call it 'athlete's foot',
with some scaling, white rash around
the moccasin distribution of the foot.
or as shown in this picture,
tinea pedis can manifest as interdigital maceration
where we have tinea basically between the toes.
This is most commonly found in folks with diabetes.
Next up is tinea corporis.
Again, also known as 'ringworm',
you can see the annular shaped lesion there.
and it kinda looks like what our patient has, right?
These would be single or occasionally
multiple, raised, annular erythematous lesions
with an irregular border, central clearing and scale.
Occasionally, we may even see a few pustules in there.
And then on the far right, tinea unguium.
More colloquially known as onychomycosis - that's a term we would
typically use but this is basically infection of the nail itself
and this is also more commonly seen in folks with diabetes
but it tends to just happen as a person gets older as well.
Alright, so looks like we'll have to
keep tinea corporis on our list for now.
The diagnosis if we want to pursue it is gonna require
a KOH prep which we'll talk more about in a little bit.
Let's move on to talk about tinea versicolor.
Now tinea, also called pityriasis versicolor
is also not a dermatophyte but it is a fungus.
It's actually a saprophytic lipid dependent
yeast, called Malassezia globosa
so it's somewhat of a misnomer that it's
still referred to as tinea versicolor.
It is in fact just normal skin flora and again
the specific microbe is called Malassezia globosa.
Risk factors for tinea versicolor are heat,
someone going to the tropics for example,
immunosuppression, hyperhidrosis or excess sweating, and if
somebody uses lots of oily lotions, that can contribute as well.
Now what we're looking for is hyperpigmented
in someone who's of white complexion
or hypopigmented in someone who is
of darker complexion, scaly macules
to the chest, the back, the upper arms.
It's very subtle as you can see in this image that we're
just seeing some very subtle hyperpigmented patches
distributed on this person's arm.
It's occasionally mildly itchy but pruritus is not one of the
most salient features of tinea or pityriasis versicolor.
Alright, so with a single, raised,
erythematous, annular shaped itchy lesion,
tinea versicolor doesn't really seem to fit in with
that diagnosis, so I think we can x that one out.