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JC WCS > Family Medicine JC128: Common Skin Conditions In Family Medicine > Flashcards

Family Medicine JC128: Common Skin Conditions In Family Medicine Flashcards

1
Q

History taking in skin conditions

A
  1. History of rash
    - site
    - **morphology (colour, shape, surface, margin, pattern, palpate)
    - **    distribution
    - duration
    - extent of involvement
    - **itch
    - pain
    - scaling
    - **    time scale of changing symptoms (minutes / hours / days)
  2. Exacerbating / Relieving factors
    - ***exposure to sunlight e.g. Urticaria
    - food
    - emotion
    - menstrual cycle / gynaecological / obstetric history
  3. Past health
    - history of previous skin diseases
    - medical diseases
    - ***drug history
  4. Occupational history
    - ***solar exposure (total accumulation of sunlight exposure) —> Skin cancer e.g. Melanoma
    - effects of skin problem on work
    - effect of work on skin problem
  5. Contact history
    - travel history
    - been to hospital / home-for-the-aged
    - close contacts having similar rash
  6. Social history
    - smoking
    - alcohol
    - substances abuse
  7. Previous investigations / treatment
    - ***OTC treatment
    - prescribed treatment
    —> how long, effects, SE
  8. Reason for consultation
    - ICE
    - ***why consult at this time?
  9. ***Impacts on ADL
  10. Sexual history, orientation, practices, history of STI
    - never leave a homosexual / transgender person unacknowledged if consultation involves relevant issues
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2
Q

Skin anatomy

A

Important structures:
1. Epidermis
2. Dermis
3. Stratum corneum (dead cells of keratinocytes)
4. Stratum basale (site of keratinocytes development)
5. Pilosebaceous unit
- Sebaceous gland
- Hair follicle

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3
Q

Solitary vs Diffuse lesion

A

Solitary lesion: ***Morphology is more important (e.g. macule / papule / nodule)

Diffuse lesion: ***Distribution is more important

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4
Q

Macule vs Patch vs Papule vs Nodule

A

Macule: **Flat area with discolouration <10 mm diameter
Patch: **Flat area with discolouration >10 mm diameter

Papule: **Elevated, circumscribed solid lesion <10 mm diameter
Nodule: Elevated solid lesion **>10 mm diameter

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5
Q

Vesicle vs Bulla vs Pustule

A

Vesicle: Blister <10 mm diameter

Bulla: Blister >10 mm diameter
—> Occur in infectious / autoimmune disease

Pustule: Vesicle containing pus
—> Occur in bacterial infections / acne

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6
Q

Wheal vs Excoriation vs Fissure

A

Wheal: Edematous lesion caused by ***swelling of dermis
- palpable, blanchable
- localised / generalised

Excoriation: a Tear usually covered with blood / serous crusts (usually caused by scratching)
- can be irregular
- usually basement membrane ***not affected

Fissure: a Linear / Wedged-shaped tear
- irregular
- might be ***deeper than basement membrane to involve deeper layers

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7
Q

Erosion vs Ulcer vs Scaling

A

Erosion: Defect in skin which does ***NOT involve basement membrane

Ulcer: Defect in skin which involves the **basement membrane / deeper tissues
- infective / inflammatory
- for **solitary ulcer: consider ***malignancy!!!

Scaling: **Thickening of the **stratum corneum with falling out like flakes
- after falling of flakes, stratum corneum may be atrophied
- seen in Psoriasis (with Plaque)

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8
Q

Plaque vs Lichenification vs Cyst

A

Plaque: Raised but still **largely flat lesion >10 mm
- large plateau
- **Psoriasis (with Scaling)

Lichenification: **Hard + thickened elevation with **exaggerated skin creases
- due to ***repeated scratching
- seen in Chronic dermatitis

Cyst: **Sac-like pocket of membranous tissue that contains fluid / air / other substances
- seen in **Acne

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9
Q

Comedones

A

Papule on the face caused by ***hyperplasia of pilosebaceous unit —> blockage of hair follicles

Closed comedone (whitehead 粉刺):
- Hair follicle ***completely blocked (melanin cannot be seen)

Open comedone (blackhead 黑頭):
- Hair follicle ***incompletely blocked (melanin can still be seen)

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10
Q

***Itchy skin rash: Diagnostic approach

A
  1. Dermatitis features e.g. Erythema, Papules, Vesicles, Excoriations
    —> Could be dermatitis
    —> **Lichenification —> **Chronic dermatitis —> Endogenous / Exogenous dermatitis
    —> **No lichenification —> **Acute dermatitis —> Endogenous / Exogenous dermatitis
  2. Wheals, transient
    —> Could be ***Urticaria
  3. Other S/S
    —> Compatible with infectious disease —> Probably an infectious disease
    —> Not compatible with infectious diseases —> Other skin rashes
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11
Q

***Endogenous vs Exogenous dermatitis

A

Dermatitis = Eczema

Endogenous:
1. **Atopic dermatitis (異位性皮炎)
2. Seborrhoeic dermatitis (脂溢性皮炎)
3. Asteatotic dermatitis (皮脂缺乏性皮炎)
4. **Pompholyx (汗泡性皮炎)
5. ***Lichen simplex (單純性平苔癬)

Exogenous:
1. Irritant contact dermatitis (刺激接觸性皮炎)
2. ***Allergic contact dermatitis (敏感接觸性皮炎)

Dermatitis pathology:
- Spongiosis: Inter + Intra-cellular edema for keratinocytes in epidermis
- Parakeratosis (nuclei still intact in stratum corneum which is abnormal in skin)
- Perivascular leukocyte infiltration

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12
Q

Atopic dermatitis (異位性皮炎)

A
  • Papules
  • Onset in early childhood
  • Presence of other ***atopic conditions
  • ***Symmetrical distribution of lesions
  • Infants: ***Extensor aspects of elbows and knees typically affected
  • Children: ***Flexor aspects of elbows and knees typically affected
  • Staphylococcal infection (have toxin): typically leads to ***Bullous impetiginisation
  • Streptococcal infection (do NOT have toxin): typically leads to ***Non-bullous impetiginisation

Complication: **Infection
1. Viral (most common): **HSV1, HPV, Molluscum contagiosum virus
2. Bacterial (most common): ***Staphylococcus aureus, Streptococcus spp.
3. Fungal: Dermatophytes, Candida spp.
4. Parasites: Sarcoptes scabiei

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13
Q

Allergic contact dermatitis (敏感接觸性皮炎)

A
  • Hypersensitivity against allergens
  • Common allergens: **Plants, **Metals, ***Chemicals
  • Erythema and ***Edema distributed along the exposed body part (e.g. ear drops, clothing straps, wrists)
  • First exposure (may not be remembered by patient): Sensitisation, usually no reaction
  • **Subsequent exposure: Reaction (Secondary immunological response) —> typically starts to erupt within **6-12 hours
  • All or Nothing response (either allergic or not allergic) —> Rash severity is ***independent on the amount / strength of sensitiser in contact with the skin
  • ***Perspiration might hasten an attack (∵ release of metal ions)
  • ***Hands are NOT typical sites of involvement —> Irritant contact dermatitis instead
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14
Q

Lichen simplex (單純性平苔癬)

A
  • Lichenification due to ***frequent scratching
  • Loop of ***positive feedback: itchy skin —> scratching —> hyperplasia of epidermis —> further pruritis —> further scratching
  • Distribution usually ***asymmetrical, depending on whether patient right / left-handed
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15
Q

Pompholyx (汗泡性皮炎)

A
  • ***Unknown cause
  • Risk factors: Atopic background, emotional stress, metal allergy
  • Rapid onset
  • Small vesicles on ***palms / soles
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16
Q

Urticaria (尋麻疹 / 風疹)

A
  • If strong tendency to develop Urticaria —> scratch can cause wide, raised red line + 10-20 minutes to fade
  • IgE-mediated immunological response
  • ***Allergens may be ingested, touched, inhaled
  • Can be caused by ***physical stimuli: cold temp, heat, sun exposure, physical pressure
  • Complication: ***Angioedema (can be fatal)
  • Cholinergic urticaria: if precipitated by heat / sweating
  • Focal / Papular urticaria: insect bite
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17
Q

***Scaly skin rash: Diagnostic approach

A
  1. Localised
    —> Acute / Subacute —> ***Guttate (Eruptive) psoriasis, Localised Pityriasis rosea, Reiter syndrome
    —> Chronic —> Localised psoriasis, Lichen planus
  2. Generalised
    —> Acute / Subacute —> **Pityriasis rosea (玫瑰糠疹)
    —> Chronic —> **    Psoriasis vulgaris (尋常)
18
Q

Psoriasis (銀屑病 / 牛皮癬)

A
  • Autoimmune disease, rapid + excessive growth of keratinocytes
  • Papules, **plaques, **distinct margins, ***silvery white scales
  • Distributions: Trunk, **Extensor aspects of extremities (elbows, knees), **Scalp

Complications:
1. Nail changes
- ***Pitting (holes on nail plate) (can be seen in normal people as well —> increased possibility of psoriasis / psoriatic arthropathy / MCTD (Mixed CT disease))
- Subungual hyperkeratosis (accumulation of keratin below nail plate)
- Onycholysis (separation of nail plate from nail bed)

  1. ***Alopecia
    - particular for scalp psoriasis
  2. ***Arthritis
19
Q

***Hyperpigmentation: Diagnostic approach

A
  1. Generalised
    —> Systemic diseases e.g. **Haemochromatosis / **Addison disease
    —> History of exposure —> ***Exogenous hyperpigmentation due to drugs / chemicals / solar-related
  2. Localised
    —> Patchy —> ***Post-inflammatory hyperpigmentation

—> Solitary lesions —> Melanocytic lesions —> **Symmetrical
——> **Benign lesions e.g. Freckles / Lentigines
——> ***Melanocytic naevi (Mole) —> Congenital (recognisable before puberty) / Acquired (recognisable after puberty)

—> Solitary lesions —> Melanocytic lesions —> **Asymmetrical —> **Dysplastic naevi, ***Melanoma

20
Q

Congenital melanocytic naevi (先天黑色素痣)

A

Congenital melanocytic naevi are usually **globular in pigment distribution
- Naevi noticed at birth behave similarly to those before onset of puberty
- **higher risk than Acquired naevi to develop malignancy —> need frequent monitoring
- ***larger size —> higher risk to become Melanoma

21
Q

Acquired melanocytic naevi (後天黑色素痣)

A
  • Acquired melanocytic naevi are usually ***reticular in pigment distribution
  • Most are first noted in young adolescence / young adulthood
  • Arrangement of pigments: usually ***reticular
  • Due to ***solar exposure —> many found in exposed region of skin
  • Occupation + Lifestyle should be assessed
  • **Lower risk to become Melanoma than Congenital naevi —> but **skin type is an important factor
    —> Type 1-6 (Very pale white skin - Dark brown / black skin)
    —> Highest risk —> Lowest risk
  • Usually persist for rest of life, but might turn hypopigmented / become palpable later
22
Q

***Hypopigmentation: Diagnostic approach

A
  1. Absolutely no pigment
    —> Congenital —> **Albinism
    —> Acquired —> Focal / segmental / generalised **    Vitiligo
  2. Some pigments intact
    —> Multiple colours —> Fairly distinct margins —> Investigations —> ***Pityriasis versicolor (aka Tinea versicolor)

—> Multiple colours —> History of inflammation, No distinct margins —> Post-inflammatory hypopigmentation

—> History of atopic dermatitis with topical corticosteroids applied —> ***Pityriasis alba

23
Q

Vitiligo (白癜風 / 白蝕)

A
  • Tissue-specific ***autoimmune disease
  • Localised / segmental / generalised
  • Pigment almost totally gone
  • ***Very distinct margins
  • **Pigmented dots seen at margin
    —> 2 populations of melanocytes (Perifollicular + Interfollicular) —> Autoimmunity attacks Interfollicular melanocytes first —> then Perifollicular melanocytes —> **    Perifollicular melanocytes still intact at margins —> Pigmented spots
  • Polygon-shaped lesions
24
Q

Pityriasis alba (白糠疹)

A
  • Usually seen in infants / children
  • History of atopic dermatitis
  • ***Post-inflammatory response
  • Pigments NOT totally disappeared
  • ***Indistinct margins
  • Fine scales might be seen
  • ***Spontaneous remission in months
25
Q

***Rashes on face: Diagnostic approach

A
  1. Erythematous papules, nodules, pustules
    —> Comedones seen —> **Acne / its variants
    —> No comedones —> **    Rosacea
  2. Scaly / Crusty lesion
    —> Examine other regions for psoriasis —> ***Psoriasis
  3. Eczematous lesions
    —> Nasolabial folds, eyebrows, eyelashes, pinnae —> ***Seborrhoeic dermatitis
    —> Perioral / Periorbital distribution —> Perioral / Periorbital dermatitis
26
Q

Acne vulgaris (尋常性痤瘡 / 暗瘡)

A
  • Severe form: ***Nodulocystic acne
  • ***NOT related to bad personal hygiene
  • Blackhead should ***NOT be removed by scrubbing —> scarring
  • Diet control ***very little role in acne management
  • Topical treatment work mainly by preventing new lesions (e.g. Vit A analogues, Topical antibiotics) —> ∴ should be applied to ***all skin areas that may be affected
27
Q

Rosacea (玫瑰痤瘡)

A
  • ***Middle-aged to elderly
  • ***Convex parts of face principally affected: Forehead, Nose, Cheeks, Chin
  • Papules, nodules
  • ***Telangiectasia
  • ***No comedone
  • Nose can be enlarged / deformed: ***Rhinophyma (酒渣鼻) (usually male only)
28
Q

Red flags / Reasons for referral

A
  1. ***Unknown diagnoses
    - Calcinosis
  2. Specialists’ management necessary
    - ***Capillary haemangioma (Strawberry naevus): risk of blocking eyesight —> amblyopia —> squint
    —> treatment with propranolol should be considered
    —> referral to ophthalmologist / plastic surgeon
  • ***Spider naevi due to Chronic liver disease
    —> referral to hepatologist
  1. **Highly generalised / erythroderma
    - drug eruption (e.g. due to Allopurinol)
    - Erythroderma: **    SJS
  2. Potential malignancies
    - A (Asymmetry): Asymmetrical
    - B (    Border): Uneven borders
    - C (Colour): Multiple colours
    - D (    Diameter): Larger than 1/4 inch
    - E (**Evolving): Changing in size, shape, colour, morphology
    - **    Induration, ***Ulcer
    —> Any one of such —> Referral
29
Q

Erythroderma

A
  • Inflammatory / scaling affecting >90% of total skin
  • Causes: drugs, dermatitis, psoriasis, leukaemia, lymphoma, 30% idiopathic
  • Effects: ***water loss, infection, pH imbalance, electrolyte imbalance
30
Q

Stevens-Johnson syndrome

A
  • Commonest causes and associations: ***Drugs, Mycoplasma pneumoniae infection, CMV infection, SLE, HIV
  • Inflammation and bullae / vesicles affecting less than 10% of skin
  • Ulcers on ***mucosal surfaces
  • Fever, sore throat, fatigue
  • ***Toxic epidermal necrolysis if >30% skin affected
31
Q

Epidermal cyst / Epidermoid cyst / Sebaceous cyst

A

**Implantation of Keratinocytes from epidermis into dermis (e.g. injection)
—> produce **keratin in dermis
—> cysts

32
Q

Purpura

A

Coagulation disorders
- Thrombocytopenia

33
Q

Viral wart on foot

A

Extragenital strains of HPV

34
Q

Keratosis pilaris

A
  • Hyperpigmentation at hair follicles
  • Very common in puberty
35
Q

Roseola (玫瑰疹)

A
  • Generalised ***exanthem occurs at day 4 of fever
  • Primary infection of human herpesvirus-6b, 6a, 7 (HHV-6, HHV-7)
36
Q

Seborrhoeic dermatitis

A

Causes:
- ***Malassezia spp. infection (Fungal infection)
- Relative immunocompromisation

37
Q

Pediculosis pubis

A
  • STD
  • infestation by ***Pthirus pubis
38
Q

Pityriasis versicolor / Tinea versicolor (汗斑)

A
  • ***Malassezia spp. infection (Fungal infection)
  • unrelated to sweat
39
Q

Pseudofolliculitis barbae

A
  • Scratching + Shaving vigorously —> Ingrown hair —> Folliculitis (Pseudofolliculitis barbae) —> Hypertrophic scar / Keloid
  • No bacteria involved
40
Q

Pityriasis rosea (玫瑰糠疹)

A
  • Christmas tree pattern (SpC PP)

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