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Medicine > Dermatology > Flashcards

Dermatology Flashcards

1
Q

How many days does normal skin take to turnover? How is this different in psoriasis?

A

Normal ~23 days

Psoriasis ~3-5 days

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2
Q

What is parakeratosis?

A

A histological sign see in psoriasis, where keratinocytes reach the skin surface with their nuclei still present - normally keratinocytes loose their nuclei before they reach the surface

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3
Q

What is ‘Auspitz sign’?

A

When the scale of psoriasis is gently scrapped it comes off easily, revealing dilated blood vessels underneath.

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4
Q

What causes sterile pustule formation in psoriasis? What variant of psoriasis are they most commonly seen in?

A

Epidermal infiltration of inflammatory polymorphs causing oedema, inflammation, erythema and pustule formation. Most commonly seen in palmoplantar pustulosis for which smoking is associated. Pustules are surrounded by erythema, and a brown discolouration and scaling usually develop.

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5
Q

What is psoriatic nail dystrophy characterised by?

A
  • onycholysis (separation of nail plate from nail bed due to abnormal cell adhesion)
  • subungal hyperkeratosis (due to excessive proliferation of the nail bed)
  • pitting (from parakeratotic cells being lost from the nail surface)
  • Beau’s lines (transverse lines due to intermittent inflammation of nail bed causing transient arrest in nail growth)
  • splinter haemorrhages (due to leakage of blood from dilated tortuous capillaries)
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6
Q

What is the median age of onset of psoriasis?

A

28 but can present from infancy to old age

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7
Q

What % of children will have psoriasis if one or both parents are affected?

A

16% if single parent, 50% if both

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8
Q

What factors and drugs might trigger onset of psoriasis?

A

Stress, infections, trauma, childbirth, beta-blockers, lithium, antimalarials

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9
Q

When psoriatic lesions first appear at sites of minor skin trauma, what is it known as?

A

Koebner’s phenomenon

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10
Q

Is psoriasis itchy, sun-sensitive and/or associated with arthropathy?

A

Usually only mildly itchy, improves with sun exposure (hence phototherapy) and may be associated with psoriatic athropathy.

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11
Q

What is the clinical presentation of psoriasis?

A

Well-demarcated hyperkeratotic scaly plaques with an erythematous base on the elbows, knees (extensor areas) and scalp (~50%). Trunk lesions are variable in size and often annular.

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12
Q

What is Guttate psoriasis?

A

Widespread small psoriatic plaques scattered on the trunk and limbs that commonly affects adolescents following a sore throat with group-beta haemolytic streptococcus. Often a family history of psoriasis. Usually completely resolves, but can be recurrent or precede onset of chronic plaque psoriasis.

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13
Q

Generalised pustular psoriasis

A

Uncommon, usually an indicator of severe and unstable psoriasis. May be precipitated by oral steroid or potent topical steroid use. Pustules usually occur initially at the peripheral margin of plaques

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14
Q

What is acrodermatitis pustulosa?

A

A variant of psoriasis that occurs in young children. Pustules appear around the nails and fingertips associated with brisk inflammation

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15
Q

What are the clinical features of flexural psoriasis?

A

A.K.A. inverse psoriasis. There are well-defined erythematous areas in the axillae, groin and natal cleft, beneath breasts and in skin folds. Minimal or absent scaling. Must be distinguished from fungal infection - mycology specimen required.

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16
Q

What is napkin psoriasis?

A

Affects infants in the nappy area with typical psoriatic lesions or more a diffuse erythematous eruption with exudative rather than scaling lesions

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17
Q

What is erythrodermic psoriasis?

A

Serious, potentially life-threatening condition with confluent erythema affecting nearly all of the skin. Scaling is absent but may precede the erythroderma. Heat and water loss main issue, often require admission. Classical psoriatic treatments (tar, dithranol, UVB) can worsen this acute psoriasis.

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18
Q

What % of patients with psoriasis have associated arthropathy? What % have a family history?

A

Psoriatic arthropathy affects 5-10% of patients with psoriasis, and of these 40% have a family history of psoriasis. Skin manifestations precede joint involvement usually but in 15% this is reversed.

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19
Q

What are the 5 recognised patterns of arthropathy associated with psoriasis?

A

1 - distal interphalangeal joints (80% have associated nail changes)
2 - asymmetrical oligoarticular (hands and feet, ‘sausage-shaped’ digits)
3 - symmetrical polyarthritis (hands, wrists, ankles, ‘rheumatoid pattern’)
4 - arthritis mutilans (digits, resorption of bone, resultant ‘telescoping’ of redundant skin)
5 - spondylitis (asymmetrical vertebral involvement, male predominance)

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20
Q

What are the three core therapies for the general management of psoriasis?

A

Topical preparations, phototherapy and systemic therapy

21
Q

What are the advantages and disadvantages of topical treatments for psoriasis?

A

Advantages
- local effects only
- self-application
- safe for long-term use
- relatively cheap
Disadvantages
- time-consuming in extensive disease
- poor compliance (insufficient amounts and frequency)
- messy
- no benefit for associated joint disease
- tachyphylaxis (treatments become less effective with continuous use)

22
Q

What topical treatments are available for psoriasis?

A
  • emollients (to help relieve itching and prevent dry skin)
  • coal tar (keratoplastic, antipuritic and antimicrobial. Good for stable chronic plaques)
  • Ichthammol (anti-inflammatory thus good for unstable psoriasis)
  • Dithranol (very irritant to normal skin)
  • Vitamin D analogues
  • Corticosteroids
23
Q

2 examples of vitamin D analogues used topically in psoriasis

A

Calcipotriol and tacalcitol they are calmodulin inhibitors, used for mild or moderate psoriasis. May get a plateau effect, best used in combination, Important not to exceed max dose to avoid risk of altering calcium metabolism

24
Q

How should steroids be used in psoriasis?

A

Topically, not systemic, and sparingly, to affected areas 1x or 2x daily. They help reduce superficial inflammation within plaques but relapse usually occurs on cessation and tachphylaxis is observed. They reduce scaling and erythema but do not reduce remission

25
Q

How can you tell the difference between scalp psoriasis and dandruff?

A
  • Scale in psoriasis is much thicker

- well demarcated plaques are present in psoriasis

26
Q

What % of patients with psoriasis have scalp involvement?

A

50%

27
Q

How does evidence suggest phototherapy works for psoriasis?

A
  • reduces antigen-presenting capacity of dendritic cells
  • induces apoptosis of immune cells
  • inhibits synthesis and release of pro-inflammatory cytokines
  • overal acts as topical immunosuppression, reducing dermal inflammation and epidermal cell turnover
28
Q

What are the contraindications for phototherapy?

A

History of previous skin malignancy or photosensitive disease e.g. lupus, prophyria, albinism or xeroderma pigmentosum. Drug history needs to be checked for photosensitising medication

29
Q

What is the recommended safety limit for phototherapy?

A

~200 individual treatments but each course is ~20-30 treatments. Hence, phototherapy should not be used as maintenance treatment.

30
Q

What are the different types of phototherapy available for psoriasis?

A

UVB (ultraviolet B) and PUVA (ultraviolet A with psoralen). PUVA is used for recalcitrant widespread thick-plaque psoriasis and palmar/plantar psoriasis.

31
Q

What some of the indications for systemic therapy in psoriasis?

A
  • Unstable inflamed psoriasis
  • Widespread disease that has failed to respond to topical/phototherapy regimens
  • Concomitant psoriatic arthropathy.
32
Q

What is the first-line systemic treatment for psoriasis? What alternative are there?

A

Methotrexate (folic acid synthesis inhibitor) or acitretin (vitamin A derivative)
Alternatives: ciclosporin, hydroxyurea, azathioprine, mycophenolate mofetil.

33
Q

What are the main side-effects of methotrexate when used for psoriasis treatment and what steps are taken to avoid them?

A

Hepatotoxicity - check LFTs before and during therapy, monitor serum procollagen III for evidence of liver fibrosis.
Myelosuppression - check FBCs regularly, give folic acid supplementation.
Adjust dose in renal impairment as it is excreted in urine.

34
Q

What are the main side-effects of acitretin when used for psoriasis treatment and what steps are taken to avoid them?

A

Hepatotoxicity and raised lipids - monitor LFTs and cholesterol/triglyceride concentrations.
Metabolite etretinate is teratogenic thus women of child-bearing age must use effective contraception during treatment and for 2 years after.

35
Q

What biological therapies are available for psoriasis?

A

Infliximab, etanercept, adalimumab (TNF-alpha inhibitors) and ustekinumab (IL-12, IL-23 inhibitor)
They can all be used for psoriatic arthritis too except ustekinumab plus golimumab (TNF-alpha inhibitor)

36
Q

When can biological therapy be considered for psoriasis?

A
  • The disease is severe (total PASI ≥10) and a DLQI >10.
  • Failed to respond to standard systemic therapies including ciclosporin, methotrexate and PUVA; or the person is intolerant to, or has a contraindication to, these treatments
37
Q

What are acute eczema eruptions characterised by?

A

Erythema
Vesicular/bullous lesions
Exudate
+/- secondary bacterial infection (staph/strep) with golden crusting

38
Q

What skin changes can occur from chronic inflammation in eczema?

A
  • scaling
  • xerosis (dryness)
  • lichenification
  • post-inflammatory hyper- or hypopigmentation
39
Q

What pathological changes in the skin are there in eczema?

A

Oedema in epidermis leading to spongiosis (separation of keratinocytes) and vesicle formation. Hyperkeratotic epidermis with dilated blood vessels and eosinophil infiltration into the dermis

40
Q

How is eczema classified?

A

Broadly into endogenous (constitutional) and exogenous (induced by an external factor).

  • Endogenous includes atopic eczema, pityriasis alba, eczema herpeticum, lichen simplex, asteatotic eczema, discoid eczema, pompholyx eczema and venous (stasis) eczema.
  • Exogenous includes contact dermatitis, photodermatitis and occupational dermatitis
41
Q

What is the typical presentation of atopic eczema?

A

Presents in infancy or early childhood, initially with facial and subsequently flexural limb involvement. Intensely itchy. Exacerbations occur associated with infections, teething, food allergies, and when older by stress. Affects 3% of infants, 90% spontaneously remit by puberty.

42
Q

What is pityriasis alba?

A

Variant of atopic eczema, patches of hypopigmentation develop on face of children.

43
Q

What is eczema herpeticum?

A

Herpes simplex infection superimposed onto eczematous skin (usually atopic). History of close contact with an adult with herpes labialis (cold sore). Characterised by fever and clusters of itchy blisters or punched-out erosions. May be life-threatening, requires systemic aciclovir.

44
Q

What is discoid eczema?

A

AKA nummular dermatitis, a common type of dermatitis in which there are round or oval blistered or dry skin lesions. May be intensely itchy. Can affect any part of the body but often the lower leg.

45
Q

What is lichen simplex?

A

AKA neurodermatitis. This localised type dermatitis or eczema follows repeated rubbing or scratching. The stimulus to scratch may be an existing skin condition such as atopic eczema or psoriasis, a compressed nerve leading to the skin (neuropathic itch or pruritus), or in some cases a bad habit.

46
Q

What is pompholyz eczema?

A

Itching vesicles on the fingers, palms and soles. The blisters are small, firm, intensely itchy and occasionally painful. More common in patients with nickel allergy.

47
Q

What is venous eczema?

A

Common insidious dermatitis on the lower legs of patients with venous insufficiency. In early stages there is brown haemosiderin pigmentation on the medial ankle, can progress to knee. Mainstay of management is compression.

48
Q

What is eczema craquelé?

A

AKA asteatotic/xerotic eczema occurs in older people with dry skin, particularly on the lower legs. Skin pattern resembles a dry river bed or ‘crazy-paving’

49
Q

What tests should patients with venous eczema have before treatment?

A

Ankle brachial pressure index measured.

Medicine (12 decks)

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