Diseases of the Hair follicles & Adnexa Flashcards
1
Q
What are the main diseases of the hair follicles & adnexa?
A
- pustular & nodular dz w/o adnexal destruction
- pustular & nodular dz w/ adnexal destruction
- atrophic dz’s of the adnexa
- dysplastic dzs of the adnexa
- dz’s of the panniculus
- lupoid onychitis (nail dz)
2
Q
What are the main pustular & nodular diseases w/o adnexal destruction?
A
- dermatophytosis (ringworm)
- superficial bacterial folliculitis
3
Q
Characteristics of superficial bacterial folliculitis
A
- hair follicles inflamed/infected
- Staphyloccocus pseudointermedius
- Secondary to coexistent dz/ predisposing factors
- Affects humans, dogs, cats, horses
4
Q
Gross lesion of superficial bacterial folliculitis
A
- transient follicular pustules leading to crusted papules
- Form at hair follicle opening, leaks, then hair follicle forms; less haired areas allow bacteria to get in easier
- alopecia, hyperpigmentation
- inguina & axilla, interdigital webs
5
Q
Characteristics of dermatophytosis
A
- superficial cutaneous, self-limiting dz caused by Microsporum spp or Trichophyton spp
- Common in calves, horses, cats
- mainly young or immunosuppressed
- colonize keratin only (dead tissue)
6
Q
Histopathological lesion of superficial bacterial folliculitis
A
- pustules w/i the infundibulum or ostium of superficial hair follicles = folliculitis
- neutrophils in the ostium
7
Q
Predisposing factors to dermatophytosis
A
- hot, humid environments
- sweat
8
Q
Gross lesion of dermatophytosis
A
- expanding circular patches of scaling & alopecia or stubbled hair
9
Q
Histopathology of dermatophytosis
A
- neutrophilic luminal folliculitis
- furunculosis (rupture of hair follicle in end-stage)
10
Q
What are pusular and nodular diseases w/ adnexal destruction?
Aka cause destruction of the hair structure
A
- Deep bacterial folliculitis & furunculosis (post-grooming furunculosis, acral lick dermatitis, interdigitial furunculosis, callus pyodrma, canine acne)
- feline acne
- canine demodicosis
- sebaceous adenitis
11
Q
Deep bacterial folliculitis & furunculosis characteristics
A
- GSD, cats
- Traumatic furunculosis –> acral lick, painful
- Self-inflicted
- furunculosis: traumatically released hair fragments & remnants of follicular keratin (FB rxn)
12
Q
What organisms are implicated in deep bacterial folliculitis & furunculosis?
A
- Staphyloccoccus pseudointermedius
- Proteus sp
- Pseudomonas sp
- E. coli
13
Q
Predisposing factors to deep bacterial folliculitis & furunculosis
A
- generalised demodicosis
- hyperadrenocorticism (Cushing’s)
- widespread actinic dz
- immunologic defects
14
Q
Gross lesion of deep bacterial folliculitis & furunculosis
A
- pustules, nodules, fistulas, haemorrhagic crusts, erosions, ulcers, alopecia, hyperpigmentation & lichenification
- fistula common
- hair follicle epithelium hyperplasia
15
Q
histopathological lesion of deep bacterial folliculitis & furunculosis
A
- haemorrhagic bullae w/ furunculosis
- +/- ulceration, neutrophils w/i hair follicle, follicle rupture, pyogranulomatous inflammation around keratin & hair shaft fragments w/i dermis
16
Q
Canine acne
A
- muzzle folliculitis & furunculosis
- deep folliculitis & furunculosis affecting chin
- unknown cause
- young dogs, short hair
- Papules –> pustules –> rupture –> nodules –> fistulae drain –> alopecia
- Histo: pyogranulomatous folliculitis & furunculosis
17
Q
Feline Acne
A
- comedo formation & secondary inflammation on chin/skin adj to lips
- No age association
- Common cause: immunosuppression
- poor grooming habits & defects in follicular keratinisation
- opportunists (Staph, Strep, P. multocida)
- Histo: comedones, rupture, furunculosis, granulomatous
18
Q
Canine Demodicosis
A
- non-contagious
- overpopulation of Demodex spp
- Juvi onset & adult onset forms
- Localised (self-limiting) or generalised (life-threatening)
- familial - young dogs CMI defect
- Isoxalines for txt
- Generalised secondary bacterial infections –> sepsis –> life-threatening
- cell-mediated immune defect
- Adult onset assoc’d w/ systemic dz (neoplasia, endocrinopathy, immunosuppressive therapy)
20
Q
sebaceous adenitis
A
- dogs/cats
- Cause: unknown; genetic in poodles/akitas
- inflammatory destruction of sebaceous glands or cornification abnormality –> sloughing –> blockage –> leakage sebum –> inflammation
- frond-shaped keratin
22
Q
Histopath of sebaceous adenitis
A
- absence of sebaceous glands w/ limited inflammation
- inflammation at one side of hair follicle - lymphocytic & granulomatous
- hyperkeratosis
24
Q
Atrophic dermatosis
A
- noninflammatory dz of hair follicle
- can pull hair out
- endocrinopathies: bilateral symmetric alopecia; hyperpigmentation; hair coat dry, brittle, dull, easily epilated; secondary pyoderma & seborrhoea common
25
Q
Histopath of atrophic dermatosis
A
- ortho/parakeratotic hyperkeratosis
- follicular keratosis
- decreased no. of hair shafts in follicular infundibular
- telogen hairs & follicular atrophy
- epidermal hypermelanosis
- dermal & sebaceous gland atrophy
- epidermis thin, thickened stratum corneum
- arrector muscles large b/c everything else is small
- increased pigmentation
- collagen in dermis atrophied
26
Q
Hypothyroidism
A
- most common endocrine SKIN disorder
- middle-aged dogs (other species assoc’d w/ iodine def & goitre)
- primary hypothyroidism (lymphocytic thyroiditis)
- Predisposed breeds: Dobie, G. Retriever, Boxer, G. Dane, I. setter
- More spec changes: myxoedema, dermal thickening, prominent hypertrophied vacuolated arrector pili muscles
27
Q
Hyperadrenocorcitism
A
- pituitary tumour (bilat adrenal cortical hyperplasia) or neoplasm of adrenal cortex
- Iatrogenic hyperglucocorticism
- over the withers area
- common in dogs
- primarily skin of trunk affected
- pendulous abd, decreased skin elasticity, slow wound healing
- calcinosis cutis
28
Q
Hyperoestrogenism
A
- middle aged-older intact dogs
- Causes: urinary incontinence or O cream; Fxnl testicular neoplasm (sertoli cell tumour); iatrogenic oestrogen admin
- Predisposed: Boxer, Shetland sheepdog, Cairn Terrier, Pekingnese, Collie, Weimaraner
- Signs: Gynecomastia, prostatomegaly, enlarged vulva; mammary enlargement, hind-end extending forwards
- Derm: symmetrical hypotrichosis originates at perineum & genitals
29
Q
Post-clipping alopecia
A
- lack of hair regrowth following close clipping
- Breeds: plush-coats
- cause unknown (thermoreg locally)
- vasc constriction at follicle prevents regrowth
- 6-12 mos before return of hair coat
- new coat may be darker
- Caution in show animals
- histo: hairs in quiescent telogen phase
30
Q
Feline Psychogenic Alopecia
A
- self-traumatic hair removal
- obsessive/compulsive disorder or anxiety neurosis
- Dx of exclusion
- well-demarcated, partial or almost complete alopecia over lateral trunk, caudal & medial thighs, abd, dorsal forelegs (inguinal region/hind legs most common)
- Excess hair present in faeces = huge hint
- histo = normal or mild inflammation
33
Q
Histo of colour dilution alopecia
A
- macromelanosomes
- follicular dysplasia
- hair fractures b/c contain large aggregates of melanin
38
Q
Gross lesion of Vx-assoc’d panniculitis
A
- focal alopecia - minimal gross inflammation, 2-3 mos post-vx
- idiosyncratic immunological rxn to rabies antigen targeting bvs
- long-haired or curly haired predisposed
39
Q
Histopath of Vx-assoc’d panniculitis
A
- ichaemic lesions of dermis (pallor & atrophy)
- accumulations of lymphocytes, fewer histiocytes, occasional plasma cells in lower dermis & panniculus surrounding bvs +/- amorphous basophilic foreign material
42
Q
Histopath of traumatic panniculitis
A
- large, central focus of loular fat necrosis
- ruptured adipocytes form large, cystic spaces
- foamy macrophages containing lipid debris
- +/- haemorrhage or haemosiderosis
- marginal fibrosis
- Walling-off fibrosis = ideal
45
Q
Lupoid Onychitis
A
- canine syndrome
- separation of claw from clawbed, sloughing of claws; regrowth of misshapen, dry, brittle, short claws
- All claws/feet
- idiopathic, but adverse rxn to food/drug admin possible
- Large breeds predisposed
- bacterial infection possible
