4,5,6,7,8. Skin Flashcards
Integumentum includes …
- hair coat
- skin
- external ear canal
- plenum nasale, foot pads
- cutaneous appendages (claws)
- perianal, circumanal glands
- paraproctal glands
Types of hairs. The cycle of the hair follicle
Guard hairs (primary) + sebaceous glans + sweat gland + musculoskeletal arector pill
Undercoat hairs (secondary) + sebaceous glands
- Anagen: active, growing period
- Catagen: transitional period, “self-killer keratinocytes”
- Telogen: “resting” period, hair retained in the follicle as a “dead hairshaft”
- Exogen: shedding phase
What is hair cycle controlled by?
- photoperiod: telogen 50% in summer, 90% in winter.
- ambient temperature
- nutrition
- hormones (thyroxin, STH <-> CS, oestrogen)
- general health state
- genetics
- poorly understood intrinsic factors (growth factors, cytokines)
Disorders of hair follicles
- Follicular atrophy: caused by alteration in factors controlling follicle cycle
- Follicular dysplasia: caused by alterations in factors that control hair follicle structure
Types of sweat glands
- Apocrin (epitrichial)
- Eccrin (atrichial, merocrin)
Apocrine sweat glands
- located where hairs are. More at the mucocutaneous junctions, interdigital area and on the dorsum
- NO on the foot pads and the nasal plane
- pheromones, IgA
Eccrin sweat glands
- ONLY on the foot pads
- deep in the dermis, subcutis, but their optimum is on the surface of the foot pad
Examination methods of the integumentum
- inspection
- palpation
- smelling
Additional:
- skin scraping + hair shift examination
- otoscopic examination of the external ear canal
- cytology
- biopsy
- blood, urine tests
- special immunological tests
What do we check in hair coat examination
- Density
- Colour
- Gloss
- Closure (how the coat fits together/to the skin)
- Occurrence of loose hair-pull ability
- Stiffness
- Localisation of abnormalities
- External parasites
How can we describe density of hair coat during integumentum examination
Hypertrichosis: excessive hair (hormonal, developmental)
Alopecia: lack of hair (partial - complete)
- hypotrichosis: partial hair loss, form of alopecia
- primary: endocrinodermatopaties, follicular dysplasia
- secondary: trauma, inflammation
Localised/generalised; single/multiple; patchy/diffuse, multifocal/focal; hereditary/congenital; symmetrical/assymetrical
What do we check in examination of the skin?
- Condition of the epidermis
- Colour and presence of haemorrhages
- Odour
- Temperature
- Moisture
- Greasiness
- Thickness
- Elasticity
- Sensitivity
- Ectoparasites
- Skin lesions
- Skin swelllings
What is difference between primary and secondary skin lesions
Primary skin lesion: is the initial eruption that develops spontaneously as a direct reflection of underlying disease. They may appear quickly and then disappear rapidly
Secondary skin lesions: evolve from primary skin lesions or are artefacts induced by the patients or by external factors such as trauma or medications
List of exclusively primary skin lesions
- Macules - not elevated, differs in colour (patch: > 1cm)
- Papules - small, solid, elevation < 1 cm
- Plaques - extensive, relatively flat
- Nodules/tuber - solid mass > 1 cm
- Wheals - urticarial lesion, flat surface
- Vesicles, bulla - circumscribed elevation filled with fluid
- Pustules, abscesses
List of exclusively secondary skin lesions
Epidermal collarette, scar, excoriation, erosion, ulcer, fissure, lichenification, callus, necrosis
What lesions can be both primary and secondary?
Alopecia, scale, crust, follicular casts, comedo, pigmentary abnormalities
Macule — ?
Circumscribed, no palpable spot up to 1 cm in diameter and characterised by a change in the colour of the skin.
Cause pigment or vascular (erythema = redness)
Primary skin lesion.
Patch — ?
Macule larger than 1 cm
Primary skin lesion
Papula — ?
Small solid elevation of the skin up to 1 cm in diameter that can always be palpated as solid mass.
Many papules are pink or red swelling produced by tissue infiltration or inflammatory cells in the dermis, by intraepidermal and subepidermal edema or by epidermal hypertrophy.
May or not involve hair follicles
Examples of papules
Erythematous papules: scabies, FAD, superficial bacterial folliculitis, allergic contact dermatitis
Plaque — ?
Larger flat-topped elevation formed by the extension or coalition of papules
E.g.: cat: eosinophil granulosa complex: eosinophil plaque
Nodule — ?
Circumscribed solid elevation > 1 cm that usually extends into deeper layers of skin
Usually result from massive infiltration of inflammatory or neoplastic cells into the dermis or subcutis. Deposition of fibrin or crystalline material also produces nodules
Tuber — ?
Inflammatory elevation of papillary zone of skin or mucus membrane with different shape and size
Tumour: large mass that may involve any structure of the skin or subcutaneous tissue. Most tumors are neoplastic or granulomatous in origin (fibroma, mastocystoma, melanoma, lipoma)
Wheal — ?
Sharply circumscribed raised lesion consisting of edema that usually appears and disappears within minutes or hours.
Usually produce no changes in the appearance of the overlying skin and haircoat.
White to pink elevated ridges or round edematous swellings that only rarely have pseudopods at their periphery.
Examples of wheals
Urticaria, insect bites, positive reactions to IDST (intrdermal skin test)
Angioedema — ?
Huge hive of a distension region such as lops or eyelids
Type 1 hypersensitivity reaction
Vesicle — ?
Sharply circumscribed elevation of the epidermis filled with clear fluid
Can be intraepidermal or subepidermal. Vesicles are rarely seen in dogs and cats because they are fragile and transient. They iccur in viral and autoimmune dermatoses or in dermatitis caused by irritants.
Up to 1 cm in diameter
Bullae — ?
Vesicles with diameter more than 1 cm
E.g. bullous pemphigoid
Cyst — ?
Epithelium-lined cavity containing fluid or solid material. Smooth, well-circumscribed, fluctuant to solid mass
Usually are filled with cornified cellular debris or cebaceous or epitrichial secretions
Pustule — ?
Small, circumscribed elevation of the epidermis that is filled with pus.
Most commonly, pustules contain neutrophils and are infectious in origin, however, eosinophils may predominate (especially in parasitic or allergic disorders) and may be sterile.
Abscess — ?
Demarcated fluctuant lesion resulting from a dermal or subcutaneous accumulation of pus. Pus is not visible on the surface of the skin until it drains to the surface. Abscesses are larger and deeper than pustules
Alopecia — ?
Loss of hair and may vary from partial to complete
Can be both primary and secondary
Possible causes of primary alopecia
Endocrine disorders, follicular dysplasia
Possible causes of secondary alopecia
Trauma or inflammation
Scale — ?
Accumulation of loose fragments of the horny layer of the skin (cornified cells). ‘The corneocyte is the final product of epidermal keratinisation. Normal loss occurs as individual cells or small clusters not visible to naked eye.
Abnormal scaling is the loss of in larger flakes. Flakes vary greatly in consistency and colour.
Possible causes of primary scaling
Colour dilution alopecia, primary idiopathic seborrhoea, follicular dysplasia
Possible cause of secondary scaling
Chronic inflammation
Crust — ?
Formed when dried exudate/serum/pus/blood/cells/scales/ medications adhere to the surface.
- tan, lightly adhering crusts are found in impetigo
- honey-coloured crusts are more commonly infectious in nature
- thicker dry yellow crusts: typical of scabies ans zinc-responsive dermatosis
- tightly adherent crusts are typical in zinc-responsive dermatosis and necrolytic migratory erythema, seborrhoea
Possible causes of primary crusts
Primary idiopathic seborrhoea, Zn-positive dermatosis
Possible causes of secondary crusts
Pyoderma, fly strike, pruritis (Scabies: dry, yellow, papulocrusta)
Comedo — ?
Dilated hair follicle filled with cornified cells and sebaceous material. Initial lesion of feline acne and may predispose the skin to bacterial folliculitis
Possible causes of primary comedo
Infection with Demodex and sermatophytosis
Vitamin A responsive dermatosis
Schnauzer comedo syndrome
Cushing’s disease
Sex hormone dermatosis
Idiopathic seborrhoea disorders
Possible cause of secondary comedo
Seborrheic skin disease
Occlusion with greasy medications or administration of systemic or topical corticosteroids
Follicular cast — ?
Accumulation of keratin and follicular material that adheres to the hair haft extending above the surface of the follicular ostia
Primary: vit A responsive dermatosis, primary idiopathic seborrhoea, sebaceous adenitis
Secondary: demodectic mange and dermatophytosis
Abnormal pigmentation
- black: melanin present throughout the epidermis (lentigo)
- blue: maelanin within melanocytes and melanophages in the middle and deep dermis (dermal melanocytoma)
- gray: diffuse dermal melanomas or superficial dermal melanosis from pigment incontinence
- brown: hemochromatosis is due to primarily to melanin nit hemosiderin
- yellow-green: accumulation of bile pigments
Hypopigmentation (hypomelanosis)
Primary: vitiligo-like disease
Secondary: post inflammatory change
Leukoderma: general term for white skin, whereas vitiligo refers to a specific disease
Leukotrichia, achromotrichia: lack of pigment in hair
Hyperpigmentation (hypermelanosis, melanoderma)
Primary: endocrine - diffuse
Secondary: post inflammatory, chronic, traumatic - latticework appearance
Epidermal collarette
Special type of scale arranged in a circular rim of loose keratin flakes or peeling keratin
Represents remnants of the roof of a vesicle/bulla/pustule/papule or hyperkeratosis caused by. Point source of inflammation as seen with papules and pustules
Excoriation
Caused by scratching, biting or rubbing. Usually result from pruritis. Often partly recognised by linear pattern
Erosion
Shallow epidermal defect that does not penetrate the basal laminar zone and consequently heals without scarring. Generally results from epidermal diseases
Ulcer — ?
Break in the continuity of the epidermis with exposure of the underlying dermis. Deep pathology process is required for an ulcer to form.
Scar (cicatrix) — ?
Area of fibrous tissue that has replaced the damaged dermis or subcutaneous tissue
Remnant of trauma or dermatological lesion.
Most scars in dogs and cats are alopecic, atrophied and depigmented
Fissure — ?
Linear cleavage into the epidermis or through the epidermis into the dermis caused by disease or injury
Have sharply defined margins and may be dry or moist. Occur when skin is thick and in elastic and then subjected to sudden swelling from inflammation or trauma, especially in the region of frequent movement.
Lichenification — ?
Thickening and hardening of the epidermis characterised by an exaggeration of the superficial skin markings. Lichenification areas often result from friction. They may be normally coloured but often are hyperpigmented.
Callus — ?
Thickened, rough, hyperkeratotic, alopecic, often lichenification plaque that develops on the skin.
Most commonly calluses occur over bony prominences and result from pressure and chronic low-grade friction
Swellings
- Oedema
- Emphysema (emphysema subcutaneum)
- Haematoma (haematoma cutis)
- Tumour (tumour cutis)
Localisation, number, size, temperature, pain, consistency, percussion, content
Cutaneous appendages
Claws, nails.
Shape, length, colour, temperature, pain, consistency, tenderness
Onychomadesis (complete loss)
Onychorrhexis (crumbling)
External ear canal
- head position
- position of the external canal
- shape of the ear
- skin of the ear pinnae and external ear canal
- pain, sensitivity of the basis of the ear
- otoscopy: skin inside, earwax (cerumen), ear drum
- test: microscopical and microbiological examination
