Superficial Fungal Skin Infection - Wright Flashcards
what is the causative organism (in general) for tinea or “ringworm”
Dermatophyte - fungi that live in soil and on animals and humans.
They are capable of digesting keratin and invading hair, skin, and nails
what are the 3 main genera of dermatophyte that cause tinea infections
Trichophyton
Microsporum
Epidermophyton
what is the most common dermatophyte infection in children
Tinea Capitis
what race is tinea capitis more common in
African American
What are the two most common causes of Tinea Capitis (what dermatophytes)
Trichophyton tonsurans
Microsporum canis
most M cani infections occur in what race of children
Caucasian
most T tonsurans infections occur in what race of children
African Americans
what is the most common transmission route for tinea capitis
human to human
asymptomatic carriage in humas appears to be a major reservoir for infection
also fomites
what are the clinical features of tinea capitis
scaling and patchy alopecia
in Tinea Capitis, is the scaling diffuse or localized?
Scaling can be diffuse (“seb-derm” like) or localized
“black dot” pattern of tinea capitis - due to broken hair shafts - which dermatophyte causes this most often?
T tonsurans it grows inside of hair shafts, weakens them, causes them to break off at scalp
if you see pustules (sign of inflammation) in the setting of Tinea Capitis, what should you have a high index of suspicion for?
primary fungal infection
need to obtain fungal culture
What is this? what is a potential consequence?
Kerion this kind of inflammation may result in permanent scarring alopecia especially if it goes on long time without proper treatment
for tinea capitis, LAD is often seen where?
posterior cervical, sub-occipital
correlates well with + fungal culture in setting of scaling and alopecia
what is the gold standard for confirming the Dx of tinea capitis?
fungal culture
Know this $$
What is the utility of KOH use for viral culture - in suspected tinea capitis or some shit?
KOH application to the biopsied scale and/or broken hairs - helps to break down the skin cells, allows you to see fungal elements
how to you diff seborrheic dermatitis from tinea capitis?
seb derm is a more chronic problem
true seb derm is unusual after infancy and before puberty
how does seb derm present in infancy (to help diff from tinea capitis)
waxy yellow scale - known as cradle cap
How does seb derm present in teens - to help diff from tinea capitis
“dandruff”
how do you diff psoriasis of the scalp from tinea capitis
erythematous plaques with silvery scale favors postauricular and posterior hairline
define alopecia areata. How do you diff it from tinea capitis
well-circumscribed smooth bald patches
generally, will not see any scales or skin changes - non-inflamed looking, no LAD
key point - what is the treatment of tinea capitis? (generally)
what specific drug is gold standard
what treatment type will not work
requires systemic antifungal to penetrate hair follicle
Griseofulvin is gold standard
topical antifungals will not work
what is unique about M canis regarding its treatment? compared to Tricophyton Toransusnusnus
M canis may require higher doses and longer course for clearance
what is the utility of an antifungal shampoo, like ketoconazole, in treatment of Tinea Capitis
may help to decrease risk of transmission
consider use by all household members shampoo
by itself will not treat the damn fungus
Terbinafine can also be used to treat tinea capitis; what are the common side effects and what should you do about them? know this $$
HA, GI upset, dizziness, drug reactions,
hepatotoxicity, rare hematologic
baseline ALT/AST is advised
CBC monitoring advised for immunodeficient pts
What is the downside of use of Terbinafine - what is it less useful for
less effective for M canis infection
if pt has a kerion, what treatment modality should you consider adding to your regimen
systemic steroids
define tinea corporis
superficial fungal infection of skin
what is the MCC of tinea corporis in young children?
M canis
what is the classic clinical manifestation of Tinea Corporis?
one or more well-defined annular scaly erythematous plaques with central clearing and a scaly, vesicular, papular, or pustular border
what is Majocchi’s Granuloma?
granulomatous folliculitis - erythematous plaques or patches studded with papules and/or nodules deeper infection of follicles foregin body reaction
what is the treatment of Majochi’s Granuloma?
cannot treat with topical antifungal
use systemic meds
how do you diff Nummular Atopic Dermatitis from Tinea Corporis?
NAD is not annular (everything round is not annular)
NAD is very very pruritic
how do you diff psoriasis from tinea corporis?
Psoriasis has “dull pink” erythema - silvery or white micacceous scale - nummular lesions - sheet like scales
how do you diff granuloma annulare from tinea corporis
granuloma annulare NO SCALES
raised, “rubbery” rim
location: dorsal hands, wrists, feet, ankles
what are the clinical manifestations of Tinea Cruris? are your johnson and jingle bells typically involved?
Pruritic (very, very, very)
red, annular, scaly plaques over groin and medial thighs
Penis, Scrotum not affected (this is helpful for dx)
how do you diff Candidiasis from Tinea Cruris?
candidiasis has satellite pustules - this is impt
How do you diff erythrasma from Tinea Cruris
Erythrasma has NO SCALES
it also appears with coral red fluorsecence if you light it up with a Wood’s lamp
Tinea pedis
“athlete’s foot”
10% world’s population
males
risk factors - occlusive shoes, communal showers (Group hug in the shower later!!)
how do you diff contact dermatitis from tinea pedis
contact dermatitis - dorsal feet affected
how do you diff Dyshidrotic eczema from tinea pedis? what is the keyword presentation of D eczema?
“tapioca vesicles”
this will be more pruritic
culture will be key to DDx here
which of the 4 patterns of Tinea unguium is most common? and describe it
Distal subungual
invasion of distal nail plate, onycholysis with thickening and discoloration
spreads proximally back towards nail matrix
which of the 4 patterns of Tinea Unguium is pathognomonic with HIV (only seen in HIV)
proximal subungual
spreads distally
which of the 4 patterns of Tinea Unguium is this?
white superficial
which of the 4 patterns of Tinea Unguium is this?
Candida - classic presentation
What is Trachyonichia? (DDx from tinea unguium)
20 nail dystrophy
may not affect all nails at first, but progress to it
“rough nails” - ridging, grooves, pitting, discoloration, fragility
What are Beau’s lines?
Transverse grooves of furrows
stress causes temporary arrest of nail matrix
nail may shed completely (Onychomadesis)
will grow back normally
I guess this is on your differential of tinea unguium
Suspect tinea unguium, what is a classic finding that will push you towards physical trauma as cause of nail dystrophy?
bilateral, symmetrical involvement of the longest toes, or the 5th toes whatever is jamming into shoes
what is the clinical presentation of tinea versicolor
multiple scaling, oval macules, patches, and thin plaques over upper trunk, proximal arms, sometimes face and neck
How do you make the dx of T versicolor? what do you look for on KOH prep?
“spaghetti and meatballs” (hyphae and spores)
you see Angular Chelitis with paronychia in the presentation, what fungal infection do you suspect
Candidiasis
angular chelitis - oral commissures - painful, erythematous, small pustules
