Lesions Flashcards
What is the difference between a primary and secondary lesion?
Primary skin lesion – develop as a direct result of the disease process
Secondary skin lesion – evolve from primary lesions or develop as a consequence of the patient’s activities
What is a secondary pyoderma
bacterial infection which is complicating an underlying skin disease
What is a papule?
Primary lesion
A small solid elevation of the skin less than 1cm in diameter
What is a nodule?
Primary leison
A solid elevation of the skin greater than 1cm in diamtere that usually extends into the deeper skin layers
What is plaque (lesion)
Secondary lesion
A large flatter elevation of the skin, sometimes formed by papules coalescing
What is a pustule?
Primary lesion
A small circumscribed elevation of the epidermis containing pus
What is a macule?
Primary lesion
A circumscribed flat area of change in colour of the skin less than 1 cm in diameter.
What is a patch?
Primary lesion
A circumscribed flat area of change in colour of the skin exceeding 1 cm in diameter.
What is scale?
Can be primary or secondary lesion
An accumulation of loose cornified fragments of the epidermis
What is crust
Secondary lesion
A dried exudate on the skin surface, either serum, blood or pus or a combination
What is an erosion?
Secondary lesion
A break in the continuity of the epidermis that does not penetrate the basement membrane
What is an ulcer?
Secondary lesion
A break in the continuity of the epidermis that penetrates the basement membrane
What is a cyst?
Secondary lesion
A cacvity with an epithelial lining
What is a wheal?
Primary lesion
A circumscribed, raised lesion consisting of dermal oedema
What is erythema?
Primary lesion
Abnormal redness of skin or mucous membranes
What is an epidermal collarette?
Secondary lesion
A circular lesion with a circular rim of scale and or a peeling edge
What is a follicular cast?
Primary lesion
An accumulation of keratinous debris around the hair shaft seen protruding from trhe follicular ostium or present when hairs are plucked and examined
What is a comedone?
Primary lesion
A dilated hair follicle devoid of hair and plugged with keratinous debris (a ‘blackhead’)
What is a sinus/fistula?
Primary lesion
An abnormal passage between a hollow organ and the skin surface
What is an excoriation?
Secondary lesion
Erosion or ulceration caused by scratching, biting or rubbing
What is lichentification?
Secondary lesion
An accentuation of the skin marking giving an elephant skin like appearance
What is a fissure?
Secondary lesion
Linear split through the epidermis into the underlying dermis
What is detected via coat brushing/combing?
superficial parasties especially fleas
What is detected using an unstained acetate tape strip?
Surface mites
What is detected using a superficial skin scrape?
surface parasites
What can be detected with a deeper skin scrape?
parasites burrowing in epidermis
What is the best site to detect a sarcoptes mite?
lesions on pinnal margin, elbows, hocks and ventrum
What are the best sites to look for demodex mites?
areas of alopecia, comedones and hyperprigmentation
What are some common pitfalls of skin scrapes?
What is demodicosis?
When mites multiply out of control
What is the appearance of a telogen hair bulb?
spear shaped
rough
no pigment
What is the appearance of an anagen hair bulb?
rounded
smooth
+/- pigmented centre
bulb may fold around shaft when plucked
What does angular broken ends of hair tips indicate?
self-inflicted hair loss and probable pruritus
What is a Wood’s Lamp exam and when would you use it?
In any patient suspected of having ringworm
Illuminate area of interest in a darkened room - microsporum canis will show green fluorescence
Negative fluorescence does not mean dermatophytosis is not present
How can you confirm dermatophytosis after performing a Wood’s lamp exam?
Perform fungal culture using McKenzie toothbrush technique
What is skin surface cytology used for?
visualising cells and microbes on skin surface
What type/site of lesion and staining is used for a direct impression smear?
Moist/greasy lesions e.g., ruptures pustule, skin under crusts
Accessible sites
Diff-quick stain (fixative, eosin and methylene blue)
What type/site of lesion and staining is used for a cotton bud smear/indirect impression smear?
Ear canal
Diff quick stain (fixative, eosin and methylene blue)
What type/site of lesion and staining is used for an acetate tape strip
Dry lesions
Less accessible sites e.g., interdigital, skin folds
Eosin and methylene blue staining
How do you perform a direct impression smear?
Glass slide pressed direct onto surface of lesion, air dried and stained
How do you perfrom an indirect impression smear/cotton bud swab?
Insert into ear canal and roll cotton bud on skin surface. Then roll sample onto microscope slide. Heat fix/air dry and stain
Why do you not use fixative (A) when staining an acetate tape strip?
may become brittle/cloudy
sample is already fixed by adhesion on tape
What methods are there to visualise cells/microbes below skin surface?
Fine needle aspiration (FNA) for cytology (placed on slide and examined under microscope)
Tissue biopsy for histopathology (sent to external lab)
When would you use bacterial culture on a skin surface swab?
If you needed to know the precise identity of a bacteria or its antibiotic suscepitibilty pattern
What skin lesion is this?
Papule
What skin lesion is this?
Nodule
What skin lesion is this?
Plaque
What skin lesion is this?
vesicle
What skin lesion is this?
Bulla
What skin lesion is this?
Patch/macule
What skin lesion is this?
Scale
What skin lesion is this?
Crust
What skin lesion is this?
Hypopigmentation
What skin lesion is this?
Hyperpigmentation
What skin lesion is this?
Erosion
What skin lesion is this?
Ulcer
What skin lesion is this?
Wheal
What skin lesion is this?
Erythema
What skin lesion is this?
Cyst
What skin lesion is this?
Epidermal collarette
What skin lesion is this?
Follicular cast
What skin lesion is this?
Comedone
What skin lesion is this?
Sinus/fistula
What skin lesion is this?
Excoriation
What skin lesion is this?
Lichenification
What skin lesion is this?
Fissure
