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Y3 MOD Dermatology > The approach to alopecia 2 > Flashcards

The approach to alopecia 2 Flashcards

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Dermatology Board Prep flashcards
1
Q

An abnormal hair cycle leads to?

A

Hair cycle arrest

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2
Q

Abnormal formation/synthesis of the hair leads to ?

A

Hair synthesis defects

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3
Q

Name the 5 parts of the hair cycle

A
  • Anagen
  • Catagen
  • Telogen
  • Exogen
  • Kenogen
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4
Q

Describe anagen in the hair cycle

A

Growing phase, where the hair shaft is produced deep in the dermis

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5
Q

Describe catagen in the hair cycle

A

Transition phase with regression of the lower part of the hair follicle, no more growth

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6
Q

Describe telogen in the hair cycle

A

Quiescent/resting phase

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7
Q

Describe Exogen in the hair cycle

A

Release and shedding of the hair

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8
Q

In primary alopecia most of the hair follicles are in which part of the hair cycle?

A

Telogen
• Lack of anagen induction
• Impaired anagen promotion
• Premature catagen

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9
Q

Give 3 examples of endocrinopathies which cause hair cycle arrest

A
  • Hyperadrenocorticism
  • Hypothyroidism
  • Hyperoestrogenism (functional testicular/ ovarian tumours)
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10
Q

What are the clinical features of alopecia due to endocrinopathies?

A
  • Symmetrical to generalised alopecia: typical to affect the trunk
  • Dull and dry coat (± scale)
  • Comedones
  • Hyperpigmentation
  • Atrophic skin
  • Poor wound healing
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11
Q

Describe the pathophysiology of hyperadrenocorticism

A
  • Glucocorticoids effect on the skin -> catabolic and antimitotic effect
  • Decreased mitoses -> thinning, delayed wound healing, pilosebaceous atrophy
  • Inhibition of fibroblast proliferation, collagen and matrix substance production -> thinning, fragile vessels
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12
Q

What signs are seen in a patient with hyperadrenocorticism

A
  • Truncal alopecia
  • Comedones
  • Skin atrophy and striae (wrinkles
  • Prominent blood vessels
  • Calcinosis cutis
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13
Q

Describe Calcinosis cutis

A
  • Inorganic, insoluble mineral salts are deposited in the dermis, subcutis or, rarely, the epidermis
  • ++ on collagen and elastin fibers in the dermis
  • Occurs with hyperadrenocorticism if steroid treatment is given for too long/too much
  • Initially start as small papules that increase in number and fuse to form a plaque
  • Lesions are very hard
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14
Q

Describe the pathophysiology of hypothyroidism

A
  • Thyroid hormone effect on the skin -> stimulation of cytoplasmic protein synthesis and increase tissue oxygen consumption
  • Initiation of anagen phase, wound healing
  • Decrease cell apoptosis –> prolonged anagen phase
  • Promote matrix cell proliferation
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15
Q

What signs are seen in a patient with hypothyroidism?

A
  • Truncal and extremity alopecia
  • Dull hair coat and hair loss on areas of friction
  • Myxoedema ‘tragic’ facial expression
  • Weight gain
  • Lethargy
  • Heat seeking
  • Rat tails: hair loss and hyperpigmentation
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16
Q

What are the causes of Hyperoestrogenism?

A
  • Functional testicular neoplasia (++ Sertoli cell tumour +/- interstitial cell tumors (rarely seminomas)
  • ++ cryptorchid testes
  • Rarely caused by ovarian tumors
17
Q

What are the effects of oestrogens on the hair cycle?

A
  • Initiation and promotion of catagen by induction of apoptosis
  • Inhibition of anagen onset -> longer telogen phase
18
Q

What is telogen defluxion and when does it occur?

A

Sudden loss of hair

- 1-3 months after a stressful event e.g. pregnancy, lactation, severe illness, surgery, shock

19
Q

What is anagen defluxion and when does it occur?

A 
Sudden hair loss
- Chemotherapy
- Severe illness
Loss of whiskers
Damage to growing hair/follicle
20
Q

Describe the features of feline paraneoplastic alopecia

A
  • Pancreatic and bile duct carcinomas, neuroendocrine pancreatic tumour, hepatosplenic plasma cell tumour
  • Alopecia ventrum and legs
  • Skin shiny and translucent – not fragile
  • Surgical excision can be curative if done in the early stages
21
Q

Alopecia X occurs in which breeds?

A

Plush coated e.g. Pomeranians, chow chows

22
Q

What are the clinical signs of alopecia X?

A
  • Primary hairs lost first (puppy coat), later complete alopecia and hyperpigmentation
  • Dull, dry coat - hair loss in frictional areas
  • Truncal alopecia and hyperpigmentation, spares extremities
  • Dog otherwise well (cosmetic disease)
23
Q

What are some types of recurrent flank alopecia?

A
  • Seasonal
  • Linked to changes in day length
  • Geographic-shaped alopecia in the thoracolumbar area
24
Q

Describe the features of injection alopecia

A
  • Unknown pathogenesis: Follicular atrophy with no inflammation
  • Focal alopecia +/- hyperpigmentation & atrophy
  • Usually local but may be remote from injection
  • Glucocorticoids, vaccines (esp. rabies)
25
Q

Describe congenital alopecia

A
  • Defect in hair follicles
  • Often associated with adnexal, epidermal, dental and nail defects (ectodermal dysplasia)
  • Dominant, recessive, X-linked
26
Q

Which breeds are affected by congenital alopecia?

A

Hairless breeds e.g. Mexican hairless, Chinese crested, Sphynx

27
Q

Follicular dysplasia is a familial disorder that affects which breeds?

A

Irish water spaniel, Portuguese water dog, curly coat retriever, Airedale, others

28
Q

‘Bald thigh syndrome’ affects which breeds?

A

Greyhounds and other sighthound breeds (Whippets, Galgo Español, and Magyar Agár)

29
Q

Describe the features of ‘bald thigh syndrome’

A
  • Bilateral hair loss on the caudal and lateral thighs
  • Alopecia may extend to the distal hind legs, the ventral abdomen and the chest and the ventral neck
  • May wax and wane
30
Q

Describe black hair follicular dysplasia

A
  • Familial disorder
  • One or more genetic defects in melanisation
  • Defect in pigmentation and hair formation
  • Progressive changes
  • Born normal, coat changes by 4 weeks
  • Black hairs become dull
31
Q

What are some methods of diagnosing hair synthesis defects?

A
  • History and clinical signs: Breed, Distribution, Coat colour
  • Trichogram
  • Rule out endocrinopathies
  • Skin biopsy and histopathology

Y3 MOD Dermatology (12 decks)

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