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GP Tan > Dermatology > Flashcards

Dermatology Flashcards

1
Q

Flat, circumscribed, < 0.5cm in diameter

A

Macule

Examples: flat nevi and cafe-au-lait spots

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2
Q

Flat, non-palpable, > 0.5cm in diameter

A

Patch

Examples: large cafe-au-lait spots and vitiligo

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3
Q

Elevated, palpable, < 0.5cm in diameter

A

Papule

Examples:
Elevated nevi, molluscum contagiosum

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4
Q

Elevated, palpable, > 0.5cm in diameter
Often formed by confluence of papules

A

Plaque

Examples: psoriasis, lichen simplex chronicus

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5
Q

Circumscribed, elevated, solid lesion, 0.5-2.0cm in diameter, in epidermis or deep tissue

A

Nodule

Example: fibromas and xanthomas

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6
Q

Larger, more deeply circumscribed, solid lesion

A

Tumours

Examples: lipomas and various neoplastic growths

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7
Q

Circumscribed, elevated, fluid-containing lesion, < 0.5cm in diameter

A

Vesicles

Examples: HSV, VZV lesions

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8
Q

Circumscribed, elevated, fluid-containing lesions, > 0.5 cm in diameter

A

Bullae

Example: burns, pemphigus, epidermolysis bullosa

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9
Q

Circumscribed elevations containing purulent exudates

A

Pustules

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10
Q

Atopic Dermatitis (Eczema)

NATURE
SX
DDX
DX
TX

A

Chronic course
Early age of onset (often childhood)
A/W +ve family history or personal history of atopy
Tend to have increase serum IgE and repeated skin infections

SX:
Severe pruritis, lichenification eruptions, dry, leathery
Antecubital fossa +/- neck, face, wrists, upper trunk
Worsens in winter and low-humidity
AKA “the itch that rashes”

DDX:
Seborrheic dermatitis, contact dermatitis, impetigo

DX: clinical

TX:
Keep skin moisturised.
Topical steroid creams (sparingly - and taper)
First line steroid sparing agent: tacrolimus ointment

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11
Q

Contact Dermatitis

TX

A

A void causative agents
Cold compression and oatmeal baths help soothe the area
Short course of topical steroids may be needed if large region of body is involved

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12
Q

Psoriasis

SX
TX

A

Immune-mediated

SX:
Well-demarcated, silvery, scaly plaques (most common type) with erythematous base
On knees, elbows, gluteal cleft, scalp
Nails may show pitting and onycholysis

TX:
Limited disease: topical steroids, occlusive dressings, topical Vit D analogs, topical retinoids
Generalised disease (involving > 30% of the body): UVB light exposure 3x per week; PUVA (psoralen and UVA) if UVB is not effective. MTX may be used for severe cases

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13
Q

Erythema Nodosum

Cause
SX
DDX
TX

A

Cause:
Primary: idiopathic
Secondary: sarcoidosis, IBD, streptococcal infections, cocciidioidomycosis, TB

SX
Inflammatory lesion - deep-seated, poorly demarcated, painful red nodules without ulceration on the extensor surfaces of the lower legs
Painful lesions may be preceded by fever, malaise, arthralgia, recent URI or diarrhea illness.

TX
Treat underlying cause
Usually self limited
NSAIDs may help with pain
Persistent cases: potassium iodide drops and systemic corticosteroids

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14
Q

Rosacea

SX
DDX
TX

A
  • chronic conditions, 30-60 years old
  • most commonly affects: fair skin, light hair and eyes, frequent flushing

SX:
- erythema with inflammatory papules (mimics acne)
- comedones are NOT present
- often elicited by spicy food, alcohol or emotional reactions
- rhinopyma (thickened, lumpy skin on the nose) may occur late in the course of disease (due to sebaceous gland hyperplasia

DDX:
- absence of comedones in rosacea
- patient’s age

TX:
Initial: control > cure
Mild cleansers (dove, cetaphil), benzoyl peroxide, and/or metronidazole topical gel +/- antibiotics

Persistent:
Oral antibiotics (tetracycline, minocycline) and tretenoin cream

Maintenance:
- Topical metronidazole OD
- Clinidine or alpha blocker - prevents flushing
- Avoid triggers
- Refer for surgery if rhinophyma is present + not responding to tx

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15
Q

Erythema Multiforme (EM)

A

Acute inflammatory disease - sometimes recurrent
Many causative agents

SX
- may precede fever, malaise, or itching/burning at the site where eruption will take place
- sudden onset of rapidly progressive symmetrical lesions
- target lesions and papules. Lesions recur in crops for 2-3 weeks

DX: clinical, biopsy may help

TX:
- antihistamine for mild cases
- prednisolone if many target lesions for 1-3 weeks
- azathioprine, levamisole (oral lesions)
- HSV EM: maintenance acyclovir or valacyclovir can reduce recurrence of both

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16
Q

Pemphigus Vulgaris
- most common subtype of pemphigus

A

Rare autoimmune disease in which blisters are formed as autoantibodies destroy intracellular adhesions between epithelial cells in the skin

SX
- flaccid bullae with erosions where bullae have been unroofed.
- oral lesions&raquo_space; skin lesions
- if not tx early, generalised, can affect esophagus
- Nikolsky’s sign +ve when gentle lateral traction on the skin separates the epidermis from underlying tissue

DX
- skin biopsy: acantholysis (separation of epidermal cells from each other)
- immunofluorescence: antibodies in epidermis

TX:
Corticosteroids and immunosuppressive agents

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17
Q

Bullous Pemphigoid

A

Autoimmune disease - antibodies against baseline membrane that lead to subepidermal bullae
More common than pemphigus vulgarian, > 60 years old

SX: large, tense bullae + other symptoms
DX: skin biopsy, immuno- and histo- pathology
TX: corticosteroids

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18
Q

Erysipelas vs Cellulitis

A

Acute inflammatory skin infection — redness, swelling, pain
Caused by Group A B-hemolytic streptococcus
Always DDX with cellulitis

Other JM info: Pain on the face:
If erysipelas on the face:
- superficial form of cellulitis of the face
- Sudden onset of butterfly erythema with a well-defined edge
- Often starts around the nose
- May have underlying sinus or dental infection — must IX
- A/W flu-like illness and fever
- Caused by Steptococcus pyogenes
- TX: phenoxymethy penicillin or di/flucloxacillin for 7-10 days

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19
Q

Management of Erysipelas / Cellulitis

A

Management:
- rest in bed
- elevate limb (in and out of bed)
- aspirin/PCM for pain and fever
- wound cleansing and dressing with non-sticking saline dressings

Streptococcus pyogenes (common cause)
- phenoxymethy penicillin 500mg QID for 10 days
reatening)

If doubtful/Staphylococcus aureus (severe,life threatening)
- Flu/dicloxacillin 500mg QID for 7-10 days
- If severe staphylococcus aureus, then IV.

Penicillin allergy
- Cephalexin 500mg QID or (if severe) IV Cephazolin 2g QID

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20
Q

Calciphylaxis

A

Serious, uncommon disease
- calcium accumulates in small blood vessels of the fat and skin tissue

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21
Q

Homan’s Sign

A

Test for DVT

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22
Q

Bancroft’s Sign

A

AKA Moses’s Sign
Test for DVT

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23
Q

Merkel-Cell Carcinoma

A
  • aggressive cutaneous neuroendocrine tumour
  • a/w polyomavirus infection, immunosuppresion, advanced age, sun exposure
  • confirm: punch biopsy

AEIOU
- Asymptomatic/non tender
- Expanding rapidly
- Immune suppressed
- Older than 50
- UV-exposed fair skin

Immunochemistry:
- CK20 positive in 90% patients
- TTFI usually negative

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24
Q

Brelow’ Classification

A

Wide excision based on tumour thickness:

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25
Q

Highest risks of developing SCC of the skin

A
  • Age over 40
  • History of non-melanoma skin cancers
  • Tendency to burn rather than tan when exposed to the sun
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26
Q

Highest risks of developing SCC of the skin

A
  • Age over 40
  • History of non-melanoma skin cancers
  • Tendency to burn rather than tan when exposed to the sun
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27
Q

Highest risks of developing SCC of the skin

A
  • Age over 40
  • History of non-melanoma skin cancers
  • Tendency to burn rather than tan when exposed to the sun
28
Q

Diffuse Melanosis Cutis (DMC)

A
  • Rare, hyperpigmentation of skin and mucous membrane —> darkening of skin, hair, peritoneal fluid, sputum, urine and sometimes the internal organs
  • Caused by increased melanin deposition (from malignant melanoma)
  • Usually seen 12 months after initial DX of malignant melanoma
29
Q

COCP is also effective against acne.
Which COCPs?

A

Cyproterone acetate (strong)
Drospirenone (strong)
Desogestral
Dienogest
Gestodene

[Medoxyprogesterone - does not help]

30
Q

Urticaria/hives (pruritic, edematous papules and plaques) after swimming in hot tub.
Suspected organism?

A

Pseudomonas aeruginosa
- usually also pustular

TX
- oral antihistamine
- avoid offending agent
- KIV antibiotics (seldom necessary)

31
Q

Yellow plaques on skin with reddish halos, think….

A

Eruptive xanthomas

  • primarily on butt and extensor surface
  • elevated TG
32
Q

Xanthomas

Tendon Xanthomas

Tuberous Xanthomas

Eruptive Xanthomas

A

Xanthomas - a/w hyperlipidaemia, inner aspects of eye

Tendon Xanthomas - a/w familial hypercholesterolaemia

Tuberous Xanthomas - a/w significant hypercholesterolaemia

Eruptive Xanthomas - a/w TG > 11

33
Q

Postherpatic Neuralgia (PHN)
- burning, sharp, stabbing and constant/intermitted pain +/- allodynia

TX for severe pain

A

Gabapentin or Pregabalin

However, if patient has renal insufficiency,
- control dose, or
- give TCA (amitriptyline) by titrating dose to effect as tolerated — watch out for anticholinergic effects

34
Q

Vitamin B3 (Niacin) Deficiency leads to Pellagra.

What is the classic triad that is sometimes present?

What are the causes of both primary and secondary pellagra?

A

Classic triad: dermatitis, diarrhoea, dementia

Primary Pellagra: deficiency in dietary tryptophan or niacin

Secondary Pellagra:
- anorexia nervousa
- chronic diarrhoea
- chronic alcoholism
- hartnup disease
- carcinoid syndrome
- colitis
- hepatic cirrhosis

35
Q

Cellulitis

Common organism?
Treatment?

A

S. Pyogenes - spontaneous rapidly spreading cellulitis
S. Aureus - less common (a/w penetrating trauma / ulceration)

TX: IV flucloxacillin / difloxacillin

36
Q

ABCD of early melanomas

A

Asymmetry
Border irregularity
Colour that tends to be very dark or blue and variable
Diameter 6mm

Evolving (enlarging, changing)

37
Q

Tinea Capitis (fungal infection of the scalp)

Types and clinical features

A
  • almost exclusively in children
  • itching, scaling, hair loss patches

Black-dot Ringworm (Trichophyton tonsurans): hair breaks off at the base leaving “black dots” in hairless patches

Grey-patch Ringworm (Microsporum canis): circular, scaly, hairless patches develop

Faves (Trichophyton schoenleinii): severe form - honeycomb destruction of the hair shaft

38
Q

Squamous Cell Carcinoma (SCC)

A
  • Scaling
  • Ulceration
  • Crusting
  • A cutaneous horn
  • Usually in sun-exposed area
  • Less common: pink cutaneous nodule without overlying surface changes
  • If spread to head and neck, may result in enlarged periauricular/submandibular/cervical LN.
  • Actinic Keratoses (AK) is the precursor that could progress to SCC
39
Q

Bowen’s Disease (SCC in situ)

A
  • Asymptomatic well-demarcated erythemous scaly patch or plaque
  • > 60 years old, but any age, rare before 30 years old
  • Most important risk factor: sun exposure
  • Easily mistaken for psoriasis or dermatitis
  • Ulceration is possible
40
Q

Basal Cell Carcinoma (BCC)

A
  • slowly growing plaque / nodule
  • skin coloured, pink or pigmented
  • varies in size from few mm to severe cm in diameter
  • spontaneous bleeding / ulceration

Three main clinical presentations: nodular, superficial, morphoeic

Nodular BCC - pearly raised edge with surface telangiectasis, central ulcer, slow growing, bleed occasionally, commonly on the face

Superficial BCC - well-defined red patch, body/limbs, looks like psoriasis/eczema/tinea (be suspicious if does not resolve with treatment for these diseases), pearly edge seen when stretched

Morphoeic BCC - least common, most difficult to diagnose, looks like poorly defined scar in sun-damaged area

41
Q

Tinea Capitis

Treatment

A

Oral antifungals: griseofulvin or terbinafine (4-8 weeks)

Topical usually not helpful

Fungal culture of scrapings and plucked hair should be done before commencing therapy

42
Q

Lichen Sclerosus

A
  • chronic inflammatory dermatosis of unknown aetiology (possibly autoimmune)
  • almost exclusively at anogenital skin
  • bimodal peak: prepubertal girls, perimenopause
  • main symptom: pruritus
  • DDX: atrophic vaginitis
  • 1st line TX: steroids
  • follow-up: 6 monthly due to risk of SCC
43
Q

What are the common autoimmune blistering diseases?

A

Dermatitis Herpetiform

Bullous Pemphigoid

Pemphigus Vulgaris

44
Q

Pemphigous Vulgaris
- an autoimmune mucocutaneous blistering disease

A

- painful, flaccid bullae, mucosal erosions,
- separation of epidermis from dermis by light friction (Nikolsky sign)
- fragile bullae that rapidly desquamates —> raw ulcers

  • autoimmune disorder: autoantibodies against desmogleins 1 and 3, which are involved in adherence between epidermal keratinocytes
  • Light microscopy: acantholysis, row of tombstones (basement membrane)
    - Immunofluorescence: IgG and C3 deposits in netlike “chicken wire” pattern
  • Serology for Ab: desmoglein 1 and 3
45
Q

Bullous Impetigo

A

Blistering condition caused by S. aureus

46
Q

Bullous Pemphigoid
- autoimmune blistering disease

A
  • pruritic, tense bullae
  • flexural surface, groin and axilla, (minority) mucosal lesion
  • Biopsy: subepidermal cleavage
  • Immunofluorescence: linear IgG deposits at the basement membrane
47
Q

Dermatitis Herpetiform
- autoimmune dermal reaction to dietary gluten

A
  • grouped pruritic vesicles
  • buttocks and extensor surface
  • Biopsy: microabscess at the tip of dermal papillae
  • Immunofluorescence: deposits of IgA Ab against epidermal transglutaminase in the dermis
48
Q

Erythema Multiforme
- cell-mediated inflammatory disorder

A
  • erythematous papules and plaques —> target lesions
  • A/W HSV
  • Biopsy: perivascular lymphocytic infiltrate and epidermal necrosis
49
Q

Lichen Planus

A

The diagnosis of LP is based primarily on examination, but biopsy can be performed for confirmation.

50
Q

Primary Syphilis

Typical presentation

A
  • Single, painless, non-pruritic ulcer with induration (eg. Chancre)
  • Bilateral, non-tender lymphadenopathy
51
Q

Benign Neonatal Rash

Examples?

Usually do not require any treatment - just observation

A
  • Erythema Toxicum Neonatorum
  • Milia
  • Milaria Rubra
  • Neonatal Pustolosis Melanosis
  • Neonatal Cephalic Pustulosis
52
Q

Hyperpigmented, hyperkeratotic area that are usually symmetrically distributed in the axillae, in the groin, on the neck, and in the cubical and popliteal fossa

What is this?

A

Acanthosis nigricans

Most common cause (insulin resistance): simple obesity, may be due to drug-induced or internal malignancy, (sometimes) idiopathic

53
Q

Recurrence of genital wart after a course of cryotherapy one year ago

Management

A

Best: wart removal using physical ablation therapy

Recurrence rate is higher with medical therapy > surgical management

54
Q

Multiple Symmetrical Subcutaneous Lipomas

A
  • benign tumours of mature fat cells
  • common, found in subcutaneous tissue
  • usually have positive family history
55
Q

Desmoid Tumours

A
  • arise from deeper layers of abdominal wall
56
Q

Epidermoid Cyst

A
  • keratinised material confined to the dermis
  • attached to the overlying skin, not mobile
  • central punctum, may become infected —> abscess
  • do not progress into malignant cells
57
Q

Neurofibromatosis Type 1
Von Recklinghausen disease

A
  • cafe-au-lait spots, pedunculated and sessile skin lesions (molluscum fibrosum)
58
Q

Highest risk factors for developing melanoma

A
59
Q

Keratochantoma is often confused with…?

A

Squamous Cell Carcinoma

Clinical Features
- crater; centre part: necrotic = looks like volcano
- considered low risk variant of SCC

Ulcerated BCC could also resemble KA, but SCC most confusing.

60
Q

Tinea Versicolour

A
  • Cause: Malassezia furfur
  • well-demarcated macular rash, hyper/hypopigmented, slightly itchy
  • Commonly seen: upper trunk / whole trunk, neck and even upper limbs
61
Q

Typical tinea Infection

A
  • Cause: dermatophytes

Annular or arcuate
Scaly and itchy
Definite edges and central clearing as it expand

62
Q

Alopecia Areata

A
  • sudden onset
  • scalp, eyebrow, beard; can occur anywhere
  • autoimmune inflammation of anlagen hair bulbs —> cessation of hair growth, not follicle destruction
  • 20% family history
  • resolves spontaneously / alopecia total is (entire scalp) or alopecia universatis (entire body)
  • Positive pull test = disease is active and more hair loss can be expected
  • Nail pitting/involvement seen in 50%

Management
Adults
Small area
- 1st line: intralesional/topical potent corticosteroids (triamcinolone acetonide / bethamethasone)
- Cannot tolerate injections: topical corticosteroids
Extensive area > 50%
- 1st line: topical immunotherapy + potent contact allergen to precipitate allergy reaction

Children
Small area
- 1st line: topical corticosteroids
Extensive area
< 10 years old - Minoxidil solution +/- topical corticosteroid

63
Q

Lipomas

Site

A

Any site of the body containing fat tissues
Although frequently subcutaneous

  • freely mobile and not attached to overlying skin
  • lobulated contour (DDX from epidermoid cyst - smooth contour)
64
Q

Mucoid Cyst

A

Bluish glistening colour, dome-shaped

  • obstructed mucoid salivary gland
  • incise if persistent or bothersome
65
Q

Nail Apparatus Melanoma (Subungual Melanoma)

A
  • fatal, frequently in 7th decade
  • longitudinal pigmented streak —> pigmented proximal nail fold (Hutchinson’s sign) —> nail plate destroyed (advanced)
  • management: digital amputation / resect from DIP joint, unless involving big toe (balance)
  • poor prognosis
66
Q

Oral Candidiasis (Thrush)

A
  • 60-75% of population, often immunodeficient.
  • tender white or yellowish patches overlying an erythematous mucosa
  • easily scraped off, leaving only an underlying red patch.

Risk factors to development of oral Candidiasis include (but not limited to):

  • Immunodeficiency
  • Cytotoxic therapy
  • Broad spectrum antibiotics
  • Corticosteroids including inhaled corticosteroids
  • Diabetes mellitus
  • HIV
  • Debility
  • Anemia (iron, folic acid, or 812 deficiency)
  • Dentures
  • Chronic xerostomia
67
Q

Skin malignancy that will most likely arise from a burn scar

A

Squamous Cell Carcinoma

Marjolin’s ulcer (less common type of SCC) - found on extremities on chronic ulcers/burn scars

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