Additional Examination Methods In Dermatology Flashcards
What are the basic diagnostic way of dermatology
History –> clinical examination -> additional examinations –> diagnosis
What are the most important additional diagnostic methods in dermatology
Skin scraping, biopsy and cytology most imp
- knowing the indication, method, evaluation of result
What can we examine in dermatology
parasites, bacteria, fungi
hair, skin
Other organs
(immune-, hormonal system)
What methods can we use to examine the skin for the physical exam
inspection / palpation / smelling / percussion
Name the additional examinations we can do
- flea comb / Wood-lamp / Otoscopy
- skin scraping + pluged hairshuft sending to laboratory
(Microscopy, microbiology, sterike swabs, cytology) - cytology (impression/swab, ear/cytobrush smear, FNA, scraping, biopsy, scotch tape)
- biopsy sampling
- allergy tests
- blood tests
- immunological tests
–> (histopathology: immunfluorescency, immunhistochemistry)
(Urine)
What additional method would you do in suspicion of fleas
Flea comb and flotation! Comb, on paper Flea dirt: digested blood If few - hard to find, they are fast! Cat: self cleaning away feces, may not find. If suscpision - treat!
What is a woodlamp used for
Nanometer light: ringworm flourescence (not specific, sensitive) but may help to guide you in direction of ringworms!
Why are gloves important to use in derma investigations!
Gloves - zoonotic skin diseasaes! Scabies, cayletiella, fungi, ringworm; microspora trichomonas …
Bacteria: staphylococci, pseudomonas - Multiresistant strains! MRSA
Why is a camera used during examinations?
Take pictures!
Compairing first with second (control) examination - change, what hasnt changed
Asking help from collegues - owner see everyday - hard to see changes
How do we approach sampling and sending samples to a lab?
Ask: what type of sample is needed for the given examination to not have to do it again if use wrong tube.
Ordering/ buying of the sampling instruments of the given laboratory (sterile swabs/ tubes with test medium/ solutions for biopsy sampling etc.)
Accompanying documents and sample labeling to avoid mixing!
How do we approach sampling for own examinations
If we’ got microscope – Skin scraping (Paraffin oil on skin surface to get more str corneaum, parasites etc. If send to lab to culture, microbio etc dont do this!!) – trichogram (eval of hair roots) – Cytology Instruments and materials – Scalpel blade, glass slide – Paraffinoil – Diff-Quick for staining – Immersion oil
What do we have to remember before performing a sample and evaluating it?
Appropiate method
– For example: if only superficial skin
scrape was taken - Cannot find demodex - live deep in follicle
- For example: if we are looking for
Sarcoptes mites - Not in lesion - run far away - scrape sample may not find any in scraping
Correct evaluation of the results
– the possibility of finding Demodex mites is less, we will have only 10-50% possibility of finding them even if we took the sample really from huge region
- Compairing the finding to lesion - eg staph aureus (normal skin flora) but no pyoderma - can negl this result
What is the method for skin scraping (for microscopic evaluation and culturing)
We should do all if have no idea of whats going on.
– Superficial (str. Corneum) / deep (Untll first amount of blood is seen - small erosion is made)
pushing out of hair follicle / pulling out hair shufts (trichogram) (If see anything filling the follicles
Also pull out hair shaft on border of healthy and skin lesion part - most fresh, most infected part)
– Huge surface / many region / border of the lesion and healthy skin (Sarcopes - fast)
– Crusts are not needed but sampling from the str. corneum (feline demodex(other demodex live in hair follicles), Ringworm - dermatophytosis
Can live on str. Corneum or they can live on hair shaft
–> need sample from both! Take sample beneath crust formation in str corneum!!!!
How do we evaluate the skin scraping (for microscopic evaluation and culturing)
– Sensitive method for ectoparasites, except Sarcoptes mites
– Bacterial culture: the antibiotic resistance is important
– Fungal culture: the only sure method for proving Dermatophytosis (Scrape + culture is the basis of diagnosis of ringworm! (PCR yes, suscpicion woodlamp no diagnosis)
What are the basic materials for own and lab sampling
Lab - swab etc. sample in sterile syringe
Own exam: slide, paraffin oil
For what infectious causes do we need multiple supf scrapings?
- (mange)Sarcoptes scabiei (var. canis, ear pinnae cat)
- (mange)=Notoedres cati (ususally found on cats ear pinnae first)
- (mites)Otodectes cynotis (ear mite, cat)
These we def find if correct sampling: - Linognathus setosus; Cheyletiella yasguri; Neotrombicula
- sucking louse (pediculosis);cheyletiellosis; trombiculosi
- ringworm/dermatophycosis: Gold standard scrape + micr culturing. Hair shaft cuticle no longer intact!!
As we should take skin scraping for sarcoptes from a huge area - what areas are the most important to do?
- Multiple supf scrapings - Predlection sites: thin skin (ear pinnae, hock, elbow, Ventral
- Overgrowth - will probably find
May only find eggs - also good for diagnosis
What is typical for dermatophycosis signs?
Patchy alopecia, caryion/inflammation,
Multiple deep scrapings - when, how
Demodicosis!
Until first capillary bleeding - demodex -> onto slide
Sharpei - thick skin - may not be able to do this sample! Biopsy may be needed
Microscopy - found on/around hair shaft/root/follicle!
(Face, back, btw toes, neck ventral/dorsal)
When do we use swabs
In case of pus
Trichocram - how do we sample for it, what are we looking for?
Hair sampling - looks like just cut some hairs off, tape on skin, (demod. Probably with root imp too)
Demodicosis: on shaft (follicle)
Dermatophytosis/ringworm: we see the hair shaft is no longer intact
Cheyletiella: eggs are found on the hair shaft.
Trichogram - how can we differentiate alopecia?
- primary vs secundary(licking etc) alopecia - easily pullable shaft indicates primary. Symmetric alopecia abdomen cat, no skin lesion indicates no licking.
- Distal end trauma indicates pruritis. (Distal end - should be sharp, if self trauma - pruritis. CAT!! Owner may not be able to see if incr self groowning, done at nigh.)
- Radix: thick radix of shaft - anagen/growth phase. 2´Alopecia due to pruritis - it grows back!
- Telogen phase: thin, primary alopecia (hormonal, aquired foll. Dysplasia) Spontanious loss. (Sligtly widened end, resting phase of hair growth - fall out)
Method of cytology
- impression-smear (glass-slide; scotch tape) Sensitive: malessia, staph, bact pyoderma (staph)
- aspiration (FNA) Nodule: inflamm vs neopl or both
- swab smear (from extarnal ear canal) Any pus, fluidy.. do a smear!!
- ”cytobrush” (PCR: papilloma/herpes etc.)
(- from skin scraping or biopsy sample)
Evaluation of dermatological cytology
– Sensitive method: bacterial and Malassezia owergrowth (easy to spot if present)
– (FNA?) Differentiation of inflammatory (septic / non septic) and neoplastic skin lesions:
– Fast, but not always giving exact final diagnosis
Describe the different smear methods
Direct smear (placing sample direcly on slide with eg a pipette; blood, or placing feces on slide and adding saline)
Impression smear (placing slide directly on surface to be sampled)
Swab smear (rolling swab with sample on slide)
Cytology - FNA
Aka fine needle biopsy
- Make vacuum inside nodule – needle in center, until we see something aspirating
- When pulling out the needle no NOT have vacuum! Contamination with skin cells..
- Big needle used
- Take off needle, aspirate a bit, put needle back on, and blow it on slide. If too thick – smear
How can you stain a scotch tape slide sample?
Same as with normal slide! (Diff quick)
Diagnostic value of HP - which skin diseases need HP for their diagnosis?
(Biopsy)
- skin tumors
- inherited/congenital diseases
- autoimmune dermatopathies
- aquired alopecia
- follicular dysplasia
- keratoseborrhoeatic skin diseases
- any case where we dont know whats going on - do biopsy!
Diagnostic value of HP - which skin diseases DOESNT need HP for their diagnosis?
- Ectoparasitosis
- pyoderma
- supf. Mycosis
- allergodermatitis (typically food allergy!)
- endocrinodermatopathies (eg. Thyroxine suppr/stim)
Cytology - how can you differentiate deep from sterile pyoderma
- Bacteria present in deep pyoderma - p. Aeruginosa, or staph spp. Which is most common, intermedius!)
- in sterile pyoderma you wont see any infectious casue, and rather a bunch of NG..
How can you recognize Malassezia pachydermatis in cytology
A yeast, they make “foot step” lesions in microscope.
Greasy skin surface typical, Rancid
Impression smear is made.
Cytobrush
Collection of cells used for cytology and PCR
Spoolie
Biopsy
- local anasthesia at site
- Scalpel – at border of healthy-disease area (we cut)
- Biopsy punch – do only at disease area!! Cant be sure the horisontal incision is taken only
from healthy if 50:50 like with scalpel - Min. 3 biopsy from each lesion + 1 from healthy region
- Cut (twist) punch in one direction only
- after:
o May get stuck in punch – pull out with needle -> put in formalin o Cut end with scissors
o Suture with 1-2 suture (dep on the diameter tho)
o Disinfect with betadine, aluminium spray
o Can also push the biopsy onto slide then stain – not so informative
Intradermal skin test, metadodic allergy test
- ONLY after excluding all other diseases, esp sarcoptes.
- A lot of false positives.. wrongly give steroids – may cause huge problem!!
- we inject different allergens in skin to check for allergic reactions (inflamm, red, hevelse..)
Blood sampling in dermatology - what can it detect?
- allergies - serology
- Sarcoptes: IgG-serology
- Blood count, biochemistry, hormones (endocrinobathies..)
Demodex mite occurance
- demodectic mange - all mammals have them! Transmission from mother at birth.
- Immunosuppr -> clinical lesion (overgrowth)
- Indicator disease (indicates immunosuppr.)
- Pyoderma – always look for them (=heavy immunosuppression!)
- common in dog, less common in cat
Diagnosis of pyoderma
Must check microscopy aswell to confirm – NG, babcteria. (Lines are seen, strands on slide – dna pushed out from NG! Pushed too hard during sampling)
