Diagnostic Tests in Dermatology Flashcards
what can a superficial skin scraping be used to diagnose?
scabies
notoedric mange
cheyletiellosis
dermatophytosis
Demodex gatoi
where should you take a skin scraping to diagnose scabies?
ear pinnae margins
elbows
hocks
where should you take skin scrapings for notoedric mange in a cat?
head
ear pinnae
neck
where should you take skin scrapings for demodicosis in a dog?
areas of spontaneous focal alopecia
pretty easy to find
where must the apple-green fluorescence be seen in a wood’s lamp test?
in the hair shafts
not on the scales
how can you differentiate self-induced from spontaneous alopecia?
self-induced: broken hairs
normal hair tips in spontaneous
what does cytology allow?
define type of inflammatory cells
define type of microbes
distinguish infection from contamination
when should you perform a bacterial culture?
if pyoderma does not respond to antibiotics
rods in cytology, especially intracellular
risk of antibiotic resistance
when should you perform a dermatophyte culture?
suspected dermatophytosis when direct trichoscopy is negative
identification of carriers
treatment control
identify species
are there any lab tests to confirm or rule out allergies?
no- clinical diagnosis
how can you diagnose a food allergy?
elimination diet with consequent re-challenge
what diseases need to be diagnosed with a biopsy?
most autoimmune diseases
most neoplastic diseases
many primary cornification disorders
what is a deep skin scraping used to diagnose?
demodex mites
not Demodex gatoi
how difficult is it to find the scabies mites?
40-50%
where should you take skin scrapings for notoedric mange?
head
ear pinnae
neck
easy to find
how should you scrape for cheyletiellosis?
back
superficial skin or tape
easy to find
what is wood’s lamp useful for?
choosing affected hairs for trichoscopy
positive in most M. canis cases
what is trichoscopy useful for?
define type of alopecia
diagnose dermatophytosis
define anagen/telogen ratio
diagnose demodicosis in dogs
some follicular dysplasia
what can you not use cytology for?
define antibiotic sensitivity
if lymphocytes are seen in the skin, alone, what is the likely diagnosis?
lymphoma
why are allergy tests performed?
only for identifying causative allergens for immunotherapy
do not confirm or rule out atopic dermatitis
which lesions can only be diagnosed by histopathology?
most of autoimmune
most of neoplastic
many primary cornification disorders (icthyosis, vitamin A responsive, Zn-responsive dermatitis), sebaceous adenitis
