Derm 12 - acquired alopciea Flashcards
Alopciea Minimum Data Base
- Skin scraping - all patients!!
- Trichogram – pluck and examine hairs microscopically > normal?
- Cytology
- Mycological culture+/-PCR?
alopecia lesion distribution
- what does it tell us about etiology? focal/multifocal? moth eaten?
Focal/Multifocal?
- consider infectious etiologies
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“Moth eaten Coat appearance (multifocal alopecic macules)?
- Hair follicle is being affected. Most common causes are :
> Bacterial folliculitis
> Demodicosis
> Dermatophytosis
should we biopsy an alopecic site? how should we do this? what should we do first / consider?
A biopsy performed in the face of infection, howsoever subtle clinically, may cloud more important underlying disease, resulting in the need for a second biopsy and owner frustration.
- Take home message:
> Whenever possible, treat infection before performing a biopsy
> Collect additional samples at the time of the biopsy for bacterial and fungal culture
> Biopsy the centre of the patch – not margins
non-infectious causes of focal / multifocal alopcia
- traction alopecia
- cutaneous T-cell lymphoma
- post-clipping alopciea
- alopecia areata
- Pseudopelade
- Vaccine associated vasculopathy
- endocrine disorders
- alopecia-X
- pattern alopecia
- Chronic recurrent flank alopecia
- Sebaceous adenitis (varies with the breed)
- colour dilution alopecia
- doberman follicular dysplasia
post-clipping alopecia
- what is it, who is at risk
- rule out
- Plush Coated Breeds are a risk – poor hair regrowth at clipped area for up to a year; has been reported to take up to 2 years
- Rule out endocrine disease
Alopecia Areata
- presentation
- why it occurs, prognosis, Tx
- Presents as well demarcated alopecic patches
- Most commonly affects head and face (commonly found on muzzle/periocularly)
- Idiopathic immune attack on the hair bulb
- mononuclear “swarm of bees“
- 60% spontaneously regrow but takes months – can try cyclosporine or immune dose of steroids if no response
Pseudopelade
- what is it, presentation
- Differs from Alopecia areata in that the attack on the hair follicles is mid isthmus
- The head is typically first affected and bilaterally symmetrical alopecic patches are noted on the forehead, periocular region, ears and chin. Hair loss can also occur on the legs and indeed become generalized. In most cases, hair regrowth is spontaneous and so treatment is not needed.
- permanent scarring alopecia?
Rabies vaccine induced vasculitis
- breeds affected
Rottweiler
Miniature poodle
Bichon frise
Silky terrier
Yorkshire terrier
Pekingese
Maltese
Miniature pinscher
However, any breed can be affected
rabies vaccine induced vasculitis clinical appearance, Dx, Tx
- when does it appear? what does it look like?
- Rabies vaccine induced vasculopathy will present with a well demarcated, alopecic, often scaly and hyperpigmented patch at the site of the rabies vaccine
- Diagnosed by clinical presentation and biopsy
- Treatment: Observation without treatment, excision > can consider pentoxifylline (oclacitinib? tacrolimus?)
<><><> - Typically, the lesion occurs within a few months of vaccination
- Focal alopecia over the site of the rabies vaccine
- +/- Hyperpigmentation, Scaling
- A generalized form has also been described that affected smaller vessel areas that are prone to ischemic damage
Is the hair loss Symmetric/Diffuse?
- what are prime suspects?
- While bilaterally symmetrical hair loss might support an endocrine etiology, don’t be fooled!
> Some pruritic patients will self-traumatize in a bilaterally symmetrical manner.
> Hair loss in patients suffering from an endocrinopathy is a result of the ease of epilation in patients whose hair follicles are in telogen
> This hair loss is generally a result of mild trauma (e.g. lying on one’s side). A patient with a side “preference” will suffer from asymmetrical alopecia
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Consider: - Hypothyroidism
- Hyperadrenocorticism
- Hyperestrogenism (possibly associated with a Sertoli cell tumor?)
> Linear preputial erythema - Alopecia-X?????
Alopecia-X
- why is it called this
- breeds
- age of onset, sex
- general progression
- this condition has gone through many names…
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Commonly recognized in double coated dogs - Pomeranians
- Alaskan Malamutes (“coat funk”)
- Siberian Huskies
- Chows
- Keeshonds
- Miniature and Toy Poodles also appear to be predisposed.
<><> - Age of onset is variable
> 1 to 10 years - No sex predilection
<><> - Initial retention of puppy coat
> preferential loss of the guard hairs
> often progresses to complete alopecia and hyperpigmentation - Alopecia tends to spare the head and extremities
alopecia X diagnosis, similar conditions
- histo?
The diagnosis is one of exclusion as endocrinopathies can have a similar presentation
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Histopathology may reveal excessive tricholemmal keratinization of late stage or delayed catagen, known as “flame follicles” and misshapen follicles; however, this can be seen in other diseases
Alopecia X and sex steroids - is there a connection?
- Adrenal Sex steroids are no longer believed to be related to Alopecia X
- Hair regrowth at site of trauma (e.g. skin biopsy site) supports the theory of receptor based pathology
Alopecia X treatment options
- Intact males with this disease will often respond to castration, but they will typically relapse within a couple of years, unfortunately (“castration responsive alopecia”)
- Melatonin can lead to hair regrowth in approximately 40% of the cases, possibly due to its effect in blocking estrogen > but careful with diabetics as it can cause insulin resistance
- In many cases, however, hair loss recurs in the face of continued treatment
- Some patients have responded to treatment with mitotane and trilostane > but risks involved with this
- condition only ‘skin deep’ > sweater?
Alopecia-X Treatment - Trilostane mechanism, efficacy
Competitive inhibitor of 3 Beta hydroxysteroid dehydrogenase (used in the treatment of hyperadrenocorticism)
- 85% of the Poms and all the poodles responded
