Defense & Barriers 2: Skin Exam/Cytology Flashcards
important things to ask in history? (5)
- presence of pruritus?
- travel history?
- diet history?
- duration/progression?
- prior therapies?
what 5 regions should be examined upon dermatologic exam?
**WHAT ARE WE AIMING FOR?
- ears
- paw pads
- claws
- mucocutaneous junctions
- oral cavity
**OVERALL, ENTIRE SKIN SURFACE
in the dermatologic exam…
1. what type of diagnostic test do we almost ALWAYS do?
2. what diagnostic test should we do if pet is ITCHY?
3. what’s the diagnostic test for HAIR PLUCKING?
- SKIN SCRAPING
- ITCHY = FLEA COMBING
- TRICHOGRAM
4 ADVANCED dermatologic tests we can run IF INDICATED?
- DERMATOPHYTE PCR
- FUNGAL culture
- BACTERIAL culture & sensitivity
- skin BIOPSY
IMPRESSION cytology steps?
Impression slides are good for WHAT TYPES OF LESIONS
ACETATE TAPE cytology steps?
how is ACETATE TAPE cytology stained?
IMPRESSION cytology
1. REMOVE crust with EDGE of SLIDE
2. PRESS SLIDE ONTO SKIN
**Good for EXUDATIVE/MOIST lesions
ACETATE tape cytology = use packing tape to press to lesion and remove
STAINED via DiffQuik stain, latter 2
- one big reason for getting a skin cytology?
- what 3 things should we be looking for?
- most animals are PRURITIC and get SECONDARY BACTERIAL INFECTIONS, good to determine
- look for INFLAMMATORY CELLS, ORGANISMS, or FREE-FLOATING KERATINOCYTES
3 things we need to do to PREP slides?
**heat-fixing acetate tape cytology?
- AIR DRY or USE BLOW DRYER
- if GREASY, then HEAT-FIX
- DiffQuik STAIN
**DO NOT HEAT-FIX TAPE SLIDES
what organism is present here?
**what’s a normal finding?
= MALASSEZIA YEAST, present in BIG PURPLE GLOBS
normal finding = BROWN MELANOCYTES
describe this organism in LOCATION
what organism is usually this SHAPE?
EXTRAcellular BACTERIA, COCCI
COCCI = STAPH
describe this organism is LOCATION
what shape?
INTRACELLULAR BACTERIA
RODS
identify this organism (genus & species)
what “shape” does it resemble?
MALASSEZIA PACHYDERMATITIS
resembles PACKING PEANUTS
what is this cell?
what does the protrusion mean?
cell = NUCLEATED KERATINOCYTE
protrusion is a BACTERIA FROM OROPHARYNGEAL REGION, so this is evidence that DOG HAS BEEN LICKING SKIN
what are the 2 steps of microscopic evaluation for SKIN CYTOLOGY? **list 2 diseases per magnification
- start with 10X magnification to identify TYPES of cells present…
–> NEOPLASTIC = HOMOGENOUS
–> INFLAMMATORY = HETEROGENOUS - go to OIL IMMERSION at 100X to identify ORGANISMS
–> BACTERIA = RODS, COCCI
–> YEAST = MALASSEZIA
3 indications for TAPE cytology?
- DRY lesions
- DIFFICULT sample sites like SKIN FOLDS or INTERDIGITAL spaces
- MALASSEZIA
ear cytology…
when should we perform it?
where do we get the sample from? (2)
how to prepare the slide after getting the sample? (2)
how do we evaluate under a microscope & what 3 things are we looking for? (2)
when should we perform it?
FOR EVERY CASE OF OTITIS
where do we get the sample from?
1. JUNCTION between HORIZONTAL & VERTICAL ear canal
2. FROM BOTH EARS regardless of clinical signs
how to prepare slide?
1. ROLL IT ONTO A SLIDE, usually towards the LEFT/FROSTED EDGE
2. HEAT-FIX & STAIN with DiffQuik
microscope evaluation?
1. start at LOW magnification 4-10X and look for “BUSY” region
2. once we get to busy region, move to OIL IMMERSION 100X and look for COCCI, RODS, YEAST
for ALL SKIN cytologies, examine at HIGH ____ and HIG
H ___
MAGNIFICATION, ILLUMINATION
skin scraping…
how often do we do it?
what clinical signs indicate it? (5)
what 2 organisms do we look for?
what 4 pieces of equipment do we need?
done for MAJORITY of skin cases
clinical signs?
1. alopecia
2. comedones
3. pustules
4. papules
5. folliculitis (DEMODEX MITES)
2 organisms?
1. DEMODEX mites (deep)
2. SARCOPTES mites (superficial, scabies)
4 pieces of equipment?
1. scalpel blade
2. mineral oil
3. cover slip
4. slides
DEEP (4) vs. SUPERFICIAL skin scraping procedure & what it looks for
DEEP skin scraping
1. PINCH skin
2. scrape until CAPILLARY BLEEDING
3. put material onto slide with MINERAL OIL & COVER SLIP
4. examine under 10X objective with DIM DIFFUSE ILLUMINATION
**LOOK FOR DEMODEX
SUPERFICIAL skin scraping
1. scrape skin with LIGHT, BROAD STROKES
2. take 3-4 sites that should be REPRESENTATIVE & any NEW LESIONS
3. put onto slide with mineral oil & COVER SLIP
4. examine under 10X objective in DIFFUSE DIM ILLUMINATION
**LOOK FOR SCABIES
identify this organism
DEMODEX MITE
identify this organism
SARCOPTES MITE (scabies)
identify this disease
SARCOPTES MITE INFESTATION (scabies)
which organism CANNOT be found in DEEP skin scrapings? what organism is it found in?
DEMODEX GATOI
found in CATS
does a NEGATIVE skin scraping mean that there’s no mites present?
NO, just means none were found, MAY NEED A TREATMENT TRIAL
identify this organism
what “shape” does it usually resemble?
EAR MITES
“coffee grounds”
ear mite preparation for DIRECT MICROSCOPY? (3)
- collect CERUMEN with a COTTON-TIPPED APPLICATOR or CURETTE
- mix with MINERAL OIL
- coverslip & examine at low magnification & DIM illumination
5 indications for TRICHOGRAM?
why do a trichogram for a pruritic cat?
3 steps including the 3 regions of hair we need to evaluate
indications?
1. pruritis
2. alopecia
3. parasites
4. dermatophytosis
5. hair follicle diseases
for CATS, can EASILY HIDE PRURITUS, so if we see BROKEN HAIRS = NOT SCRATCHING
3 steps?
1. PLUCK hairs with FORCEPS PERIPHERAL to the lesion
2. place in MINERAL OIL on SLIDE
3. examine HAIR SHAFT, HAIR BULB & DISTAL END of hair
identify
DERMATOPHYTOSIS (fungus)
identify
MELANIN CLUMPING so PIGMENT NOT EVENLY DISTRIBUTED THROUGH HAIR SHAFT
identify
LOUSE EGGS
identify & what type of organism
CHEYLETIELLA egg, BIG MITE
identify
CHEYLETIELLA
flea combing…
what 2 clinical signs indicate it?
what are we looking for?
if we find it, what should we do?
if there are SCALES, what do we do & what are we looking for?
2 clinical signs?
1. ALOPECIA
2. PRURITUS
what are we looking for?
FLEA DIRT/FECES, looks like dark pepper
if we find it, what do we do?
PLACE MATERIAL ON WET PAPER TOWEL & IF IT TURNS RED, THEN IT’S FLEA FECES
if there are SCALES…
1. scrape up scale and PLACE ONTO SLIDE WITH MINERAL OIL
2. look for CHEYLETIELLA
identify condition
FLEA INFESTATION
wood’s lamp examination…
2 indications?
for what organism?
procedure? (2)
what SPECIFICALLY is being illuminated?
FOR DERMATOPHYTOSIS
2 indications?
1. alopecia
2. suspect dermatophytosis
procedure?
1. hold wood’s lamp 2-4 cm away from skin surface in DARK ROOM
2. look for APPLE-GREEN FLUORESCENCE under UV LIGHT
TRYPTOPHAN METABOLITE of DERMATOPHYTE WILL FLUORESCE in UV LIGHT
fungal culture…
what does it aim to do?
indications? (2, one particularly in cats)
procedure? (5, including how we collect sample)
aims to CONFIRM FUNGAL INFECTION
indications?
1. alopecia
2. FOLLICULITIS (cats)
procedure?
1. collect HAIR/SCALE from LESION or HAIR THAT FLUORESCES under Wood’s Lamp
–> can collect via MACKENZIE TOOTHBRUSH METHOD
2. then, EMBED TOOTHBRUSH GENTLY IN CULTURE MEDIUM
3. incubate for 3-4 weeks IN DARK, HUMID ROOM at ROOM TEMP
4. CHECK DAILY for WHITE, FLUFFY SPORES
5. use ACETATE TAPE to PLACE ON SLIDE & EXAMINE
identify organism & technique
FUNGAL CULTURE
MICROSPORUM CANIS
identify organism
MICROSPORUM CANIS (fungus)
label & WHAT DISEASE ARE THESE LESIONS FROM
BACTERIAL FOLLICULITIS
indications for BACTERIAL CULTURE & SENSITIVITY? (5)
MANY!!!
- history of DRUG-RESISTANT infections
- DEEP pyoderma
- RECURRENT or RELAPSING pyoderma
- empiric antibiotic FAILURE
- suspected UNCOMMON or ATYPICAL bacterial infection
biopsy & histopathology 3 indications?
**which of the 2 is done more commonly?
**SKIN BIOPSIES DONE COMMONLY
- Suspected NEOPLASIA, AUTOIMMUNE or METABOLIC Dz
–> Want to ensure that we’re not missing a disease that mimics allergies - Condition that requires EXPENSIVE, EXTENSIVE, OR HAZARDOUS TREATMENT
- Failure to respond to appropriate therapy
skin biopsy…
4 goals?
3 methods of restraint?
2 steps of SITE PREPARATION (& what NOT to do)?
how many lesions to sample?
4 goals?
1. establish DEFINITIVE diagnosis
2. rule out OTHER DISEASES
3. determine PROGNOSIS
4. PRIORITIZE DDxs
restraint?
1. LOCAL anesthesia like LIDOCAINE and MINOR PHYSICAL restraint, can use EPINEPHRINE/LIDOCAINE for HEMOSTASIS
2. SEDATION if necessary
3. GENERAL ANESTHESIA for DIFFICULT SITES
–> nasal planum, footpads, claws, periocular skin, pinnae
site PREPARATION?
1. CLIP HAIR CAREFULLY but DO NOT SCRUB (not a sterile procedure)
2. make sure to MARK SITES prior to LIDOCAINE ADMINISTRATION bc it’ll make lesions VANISH
sample 3-4 lesions
punch biopsy 3 steps
- Rotate gently in ONE DIRECTION and APPLY GENTLE PRESSURE until BLADE ENTERS SQ TISSUE
- Then, GENTLY GRASP PEDICLE OF UNDERLYING SQ fat and GENTLY CUT WITH IRIS SCISSORS (DO NOT CRUSH)
- finally, FIX SAMPLE IN FORMALIN
