Dermatology

Question 1

What are the clinical features of atopic eczema?

Answer 1

Risk factors:

• genetic predisposition (family history)
• atopic triad: asthma, hayfever, eczema
• exposure to irritants: soaps, heat, infection, stress

Clinical features:

• itchy ++
• erythematous
• diffuse
• flexural surfaces (thinnest skin)
• worse in winter (dry)
• worse in summer (heat)

Question 2

What is the pathophysiology of atopic eczema?

Answer 2

• Eczema is a combination of genetic susceptibility with environmental triggers
• Many patients with eczema have a defective mutation in fillagrin.
• When the skin is stressed (due to triggers), then the skin’s waterproof barrier is lost.
• Antigens enter the skin through the broken barriers, triggering a Th2 immune response
• Flexor skin surfaces are more susceptible because the skin is thinner

Question 3

What are the two main complications of eczema?

Answer 3

1. Bacterial superinfection
   - eczematous skin lacks naturally occurring antibacterial peptides
   - superinfection with Staph. aureus produces a golden crust
2. Eczema herpeticum
   - secondary infection by HSV virus
   - painful vesicles and “punched out” erosions
   - medical emergency
   - risk of corneal scarring

Question 4

What are the treatments for atopic eczema?

Answer 4

General measures:

• avoid soap
• regular emollient
• warm, not hot showers
• avoid overheating/drying

Specific measures:

• topical steroid to inflamed areas
• mild steroid or NSAID creams (pimecrolimus) for face
• treat infection if suspected with systemic abx/antiviral as indicated

Additional treatment options:

• wet dressings
• phototherapy with UVB
• systemic immunosuppression (short term: oral prednisolone; medium to long term: azothioprine, cyclosporin A, methotrexate)

Question 5

What are the clinical features of psoriasis?

Answer 5

Classical appearance:

• symmetrical
• extensor surfaces
• silvery scales
• well demarcated
• erythematous/salmon pink
• +/- itchiness

Risk factors:

• family history
• age of onset 20s or 50s

Areas affected:

• scalp
• ears
• genitals (looks different)
• palms and soles of feet
• nails

Question 6

What is the basic pathophysiology of psoriasis?

Answer 6

Like eczema, it is an interaction between genetics and environmental triggers.

• T cell response
• important cytokines: TNF alpha

Question 7

What is the treatment for psoriasis?

Answer 7

General measures:

• stop smoking
• reduce stress
• reduce scratching
• regular emollients

Specific treatments:

• topical: corticosteroid cream, calcipotriol (reduces proliferation), tars (anti-inflammatory), keratolytics
• phototherapy: UVB has anti-inflammatory/immunosuppressive properties
• systemic: methotrexate, acitretin, cycosporin A
• biologic therapies: infliximab (TNF-alpha inhibitor)

Question 8

What are the four components of acne?

Answer 8

1. Abnormal keratinisation of sebaceous duct - white head or black head
2. Colonisation with bacteria
3. Increase in androgen leading to increased sebum production
4. Oil + bacteria = inflammation

Question 9

What are the characteristics of melanoma?

Answer 9

Remember ABCDE

1. Asymmetry
2. Border irregularity
3. Colour variegation
4. Diameter >6mm
5. Evolving/erythema/everything else (satellites, skin type, presence of metastatic disease)

Question 10

What are the important features on history of a patient presenting with a suspected melanoma?

Answer 10

Prior history of melanoma
Blistering sunburn in childhood
Skin type
Use of solarium
Family history of melanoma or other malignancy
Constitutional symptoms (rare with primary melanoma, usually with metastatic disease): weight loss, lethargy, night sweats

Question 11

What information is provided on a pathology report about an excised melanoma?

Answer 11

1. Breslow thickness (prognostic, informs TNM staging)
2. Ulceration
3. Mitotic count
4. Clark level (relevance?)
5. Melanoma subtype (superficial spreading, lentigo maligna, nodular, acrial lentiginous, desmoplastic)

Question 12

After excision biopsy, what is the management of the primary melanoma?

Answer 12

1. Wide local excision

2. Sentinel node biopsy (if >1mm thickness)

Question 13

What is the Breslow thickness system?

Answer 13

Measures the thickness of the melanoma lesion.
Informs T stage

<1 mm has good prognosis (T1)
>4 mm has poor prognosis (T4)

Question 14

Where might you find palpable lymph nodes secondary to a primary melanoma?

Answer 14

Depends on location of melanoma.

• head and neck melanoma = cervical lymph nodes
• arm melanoma = axillary lymph nodes
• leg melanoma = inguinal lymph nodes
• trunk melanoma?