Dermatology Flashcards by Richard Wu

Erythematous, annular patches

“Wood-grain” appearance

Diagnosis? Associated with what malignancy?

Erythema gyratum repens

Associated with lung cancer

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Pityriasis rosea - caused?

HHV-7

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Steroid ladder + examples

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Tx for acne vulgaris

(1) Topical retinoid

+/- Topical ABx +/- Oral ABx (doxycycline, erythromycin)

+/- Topical benzoyl peroxide

+/- Topical Azelaic acid

If cycle related –> COCP

If resistant –> Isotretinoin (S/E: Dry skin, eyes, mouth, nosebleeds, suicide)

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Middle-aged (30-60 year old)

Triggered by Alcohol and Spicy food

**Flushing**

Papules, Pustules

Telangiectasis

Diagnosis? Treatment?

Acne rosacea

(1) Topical metronidazole
(2) Oral tetracycline or erythromycin

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Inherited

Skin fragility

Blistering of skin and mucous membranes

Diagnosis? Cause?

Epidermolysis bullosa

Mutations in Laminin V

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Itchy, deep, tense, bullae

No mucosal involvement

Diagnosis? Ix? Tx?

Bullous pemphigoid

Itchy, deep, tense, bullae + No mucosal involvement

IgG and C3 linear deposition at the dermoepidermal junction

Tx: oral corticosteroids

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Flaccid bullae

Mucosal involvement

Diagnosis? Ix? Tx?

Bullous pemphigus (Pemphigus vulgaris, Pemphigus foliaceus)

Flaccid, superficial bullae + Mucosal involvement

Ix: auto-antibodies against desmoglein –> acantholysis

loss of intercellular connections between keratinocytes

Tx: oral prednioslone

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Itchy, dry skin

Vesicles

Punched out ulcerations

Diagnosis? Cause? Treatment?

Eczema herpeticum

Caused by HSV 1/2

IV Aciclovir

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Tx for treatment resistant hand dermatitis

(1) Emollients
(2) Aliretinoin

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Types, Pathogenesis and Ix for contact dermatitis

Allergic contact dermatitis –> Type IV hypersensitivity reaction (sub-acute onset)

Irritant contact dermatitis –> due to friction or chemical damage (acute onset)

Ix: Patch testing

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Itchy, red, scaly lesions

on head, nasolabial folds, scalp

Diagnosis? Cause? Treatment? Complications?

Seborrhoeic dermatitis

Caused by Malassezia furfur

If scalp –> Topical shampoo

If face and body –> Topical ketoconazole

Complications: Blepharitis, Otitis externa

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Hot climate

Multiple, small, itchy blisters/vesicles

on fingers, palms and soles of feet

Diagnosis? Differential?

Pompholyx dermatitis

Difficult to DDx from palmoplantar pustulosis (psoriasis in other areas)

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Acute onset

Target lesions

Mucosal involvement

Diagnosis? Cause? Prognosis?

Erythema multiforme

EM minor –> no mucosal involvement

EM major –> mucosal involvement

Caused by infections (HSV, Mycoplasma) or drug reactions

Good prognosis as self limiting

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Painful, red, subcutaneous nodules on shins

Diagnosis? Cause? Next Ix? Prognosis?

Erythema nodosum

Causes

Infection
- Streptococcal throat infection
- TB
IBD
Sarcoidosis
Hodgkin’s lymphoma
Pregnancy

CXR to look for sarcoidosis or TB

Good prognosis as self limiting

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Hot water bottle

Ertyematous patch with areas of hyperpigmentation

Diagnosis? Next Ix?

Erythema ab igne

Often related to chronic pain ? bone metastases

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Erythema marginatum

What does it look like?

Associated with?

Rheumatic fever

Erythema marginatum

Causing pink border with fading centre (central clearing)

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Expanding patch of erythema

Classical bull’s eye appearance

Diagnosis? Associated with?

Erythema chronicum migrans

Lyme disease

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Purple, pruritic, papular, polygonal rash

on flexor surfaces

Wickham’s striae (white reticular webs)

Diagnosis? Cause? Tx?

Lichen planus

Unknown cause ? autoimmune

Clinical diagnosis

Tx: High dose topical steroids

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Elderly woman

Vulval itching

Hypopigmentation

Fragile skin / White parchment paper

Diagnosis? Tx? Complications?

Lichen sclerosus

Unknown cause ? autoimmune

Clinical diagnosis

Tx: high-dose topical steroids

Complications: Vulval cancer (5%)

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Tx for pressure ulcers

Pressure-reducing aids

Repositioning

Hydrocolloid dressings + Hydrogels (moist environment encourages ulcer healing)

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Triggers for psoriasis

Drugs
- B blockers
- Lithium
- Withdrawal or oral steroids
- Anti-malarials
Alcohol
Smoking
Post-partum
Trauma / Kobner phenomenon

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Sore throat 2 weeks ago

Acute onset

Red, scaly, tear-drop lesions

Diagnosis?

Guttate psoriasis

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Recent withdrawal of oral steroids

Erythema with yellow pustules

Systemic symptoms

Diagnosis?

Generalised pustular psoriasis

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Chronic onset **pustules and erythema on palms and soles** Smoking Diagnosis?

**Palmoplantar pustulosis**

**_Smooth_** **Itchy, red skin** **Flexural surfaces** No scale Diagnosis?

**Flexural psoriasis**

Features of nail psoriasis

Tip: POSH ## Footnote **Pitting of nails** **Onchyolysis** **Subungual Hyperkeratosis**

Subtypes of psoriatic arthritis

Tx for plaque psoriasis Tx for scalp psoriasis Tx for flexoral psoriasis

**Gum bleeding** **Brusing** **Gingival discolouration** Diagnosis? Ix? Tx?

**Vitamin C deficiency / Scurvy** Ix: **serum L-ascorbic acid** Tx: Replace Vitamin C

**Started a new drug** **Acute onset** **Skin + mucosal involvement** (Diffuse skin pain) (Bullae) **Targetoid lesions** Diagnosis? Classification?

**School child** **Slapped cheek appearance** (Sparing of nasal ridge) **Lacy reticular erythema** Diagnosis? Cause? Tx?

**Erythema infectiosum** **Parvovirus B19** Tx: supportive

**Golden crusted lesion** **Itchy** **Children** Diagnosis? Cause? Tx?

**Impetigo** **Staph aureus** or **Strep pyogenes** Fusidic acid +/- Flucloaxcillin

**Umbilicated pearly papule** **Henderson-Patterson bodies** Diagnosis? Cause?

**Molluscum contagiosum** Pox virus

**Initially scaly, salmon-pinnk patch on the trunk** **Now multiple red scaly ovale lesions in a christmas tree distribution** Diagnosis? Cause? Tx?

**Pityriasis rosea** **HHV-7** Tx: none required as self limiting

**Hypopigmentation on trunk** **More noticeable after skin tan** Diagnosis? Cause? Tx?

**Pityriasis versicolour** Malassezia furfur (1) Topical ketoconazole shampoo

Progression to SCC

**Actinic keratosis** (Precursor lesion to SCC) --\> **Bowen's disease** (in situ tumour) --\> **Invasive SCC** --\> **Metastatic SCC**

**Dome shaped papule on sun damaged skin** **Keratin filled crater** **Little volcano** Diagnosis?

Keratoacanthoma

**Non-healing painless ulcer** **Arises from chronic wound / burns** Diagnosis?

Marjolin ulcer

Tx for Bowen's disease

(1) Topical therapies * **Topical imiquimod** * **Topical 5-FU** **(2) Surgical excision**

**Itchy, erythematous macule with overlying scale / crust** **sun-exposed areas** Diagnosis? Tx?

**Actinic keratosis** * **Topical Fluorouracil** (5FU) cream (5%) * **Topical Imiquimod** (5%) cream Risk of progression Actinic keratotis --\> Bowen's disease --\> SCC

**Itchy, erythematous macule with overlying scale / crust** **Biopsy shows dysplasia with intact basement membrane** Diagnosis? Tx?

Bowen's disease (SCC in situ) * **Topical Fluorouracil** (5FU) cream (5%) * **Topical Imiquimod** (5%) cream Risk of progression to SCC

Precursor lesion to melanoma

* **Benign naevus** * **Solar lentigo**

Types of malignant melnoma

? melanoma Next Ix?

All NEW + irregular black lesions with ABCDE features MUST be **excised for biopsy**

Most important prognostic factor for malignant melanoma

**Breslow thickness** [the single most important prognostic factor]

**Trauma** **Soft, round, mobile, superficial, painless mass** Diagnosis?

Lipoma

**Free-moving, firm skin nodule** **Pinch sign (forms a dimple)** Diagnosis?

**Dermatofibroma** Non-cancerous

**Stuck on appearance** **Warty surface** **Multiple** Face, Trunk, Back Diagnosis?

**Seborrhoeic keratosis** (Barnacle)

**Velvety, hyperpigmentation of the skin** Neck, Axillae, Groin +/- Mucosal involvement

**Acanthosis nigricans** Associated with * Insulin resistance * Gastric cancer

**Widespread, thick, dry "fish-scale" skin** Diagnosis? Associated with?

**Acquired ichthyosis** Associated with **Lymphoma**

**Necrolytic migratory erythema** Associated with

Glucagonoma

**Migratory thrombophlebitis** Associated with?

**Pancreatic cancer**

**Pregnant** **Flat, symmetrical, brown patch on cheeks** Diagnosis?

Melasma

**Pregnancy** **Itchy, red lesions** **On stretch marks** **Sparing umbilicus** Diagnosis?

**Polymorphic eruption of pregnancy (PEP)**

**Pregnancy** **Multiple bilsters on abdomen** Diagnosis?

**Pemphigoid gestationis** | (Autoimmune)

Osler-Weber-Rendu syndrome AKA Cause? Clinical features?

Hereditary haemorrhagic telangiectasia = Osler-Weber-Rendu syndrome Autosomal dominant * Recurrent nosebleeds * Telangiectasia * GI Telangiectasia * Pulmonary AVM

Causes of hypopigmentation Causes of hyperpigmentation

Tx for facial hirsuitism

Topical eflornithine

well demarcated patches of hair loss small, broken, "exclamation mark" hairs Diagnosis? Cause?

**Alopecia areata** Autoimmune

Tx for Hyperhidrosis

(1) **Topical aluminium chloride** S/E: Skin irritation