Dermatology Flashcards
Flat, circumscribed, < 0.5cm in diameter
Macule
Examples: flat nevi and cafe-au-lait spots
Flat, non-palpable, > 0.5cm in diameter
Patch
Examples: large cafe-au-lait spots and vitiligo
Elevated, palpable, < 0.5cm in diameter
Papule
Examples:
Elevated nevi, molluscum contagiosum
Elevated, palpable, > 0.5cm in diameter
Often formed by confluence of papules
Plaque
Examples: psoriasis, lichen simplex chronicus
Circumscribed, elevated, solid lesion, 0.5-2.0cm in diameter, in epidermis or deep tissue
Nodule
Example: fibromas and xanthomas
Larger, more deeply circumscribed, solid lesion
Tumours
Examples: lipomas and various neoplastic growths
Circumscribed, elevated, fluid-containing lesion, < 0.5cm in diameter
Vesicles
Examples: HSV, VZV lesions
Circumscribed, elevated, fluid-containing lesions, > 0.5 cm in diameter
Bullae
Example: burns, pemphigus, epidermolysis bullosa
Circumscribed elevations containing purulent exudates
Pustules
Atopic Dermatitis (Eczema)
NATURE
SX
DDX
DX
TX
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
Contact Dermatitis
TX
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
Psoriasis
SX
TX
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
Erythema Nodosum
Cause
SX
DDX
TX
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
Rosacea
SX
DDX
TX
- 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
Erythema Multiforme (EM)
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
Pemphigus Vulgaris
- most common subtype of pemphigus
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»_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
Bullous Pemphigoid
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
Erysipelas vs Cellulitis
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
Management of Erysipelas / Cellulitis
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
Calciphylaxis
Serious, uncommon disease
- calcium accumulates in small blood vessels of the fat and skin tissue
Homan’s Sign
Test for DVT
Bancroft’s Sign
AKA Moses’s Sign
Test for DVT
Merkel-Cell Carcinoma
- 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
Brelow’ Classification
Wide excision based on tumour thickness:
Highest risks of developing SCC of the skin
- Age over 40
- History of non-melanoma skin cancers
- Tendency to burn rather than tan when exposed to the sun
Highest risks of developing SCC of the skin
- Age over 40
- History of non-melanoma skin cancers
- Tendency to burn rather than tan when exposed to the sun
Highest risks of developing SCC of the skin
- Age over 40
- History of non-melanoma skin cancers
- Tendency to burn rather than tan when exposed to the sun
Diffuse Melanosis Cutis (DMC)
- 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
COCP is also effective against acne.
Which COCPs?
Cyproterone acetate (strong)
Drospirenone (strong)
Desogestral
Dienogest
Gestodene
[Medoxyprogesterone - does not help]
Urticaria/hives (pruritic, edematous papules and plaques) after swimming in hot tub.
Suspected organism?
Pseudomonas aeruginosa
- usually also pustular
TX
- oral antihistamine
- avoid offending agent
- KIV antibiotics (seldom necessary)
Yellow plaques on skin with reddish halos, think….
Eruptive xanthomas
- primarily on butt and extensor surface
- elevated TG
Xanthomas
Tendon Xanthomas
Tuberous Xanthomas
Eruptive Xanthomas
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
Postherpatic Neuralgia (PHN)
- burning, sharp, stabbing and constant/intermitted pain +/- allodynia
TX for severe pain
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
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?
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
Cellulitis
Common organism?
Treatment?
S. Pyogenes - spontaneous rapidly spreading cellulitis
S. Aureus - less common (a/w penetrating trauma / ulceration)
TX: IV flucloxacillin / difloxacillin
ABCD of early melanomas
Asymmetry
Border irregularity
Colour that tends to be very dark or blue and variable
Diameter 6mm
Evolving (enlarging, changing)
Tinea Capitis (fungal infection of the scalp)
Types and clinical features
- 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
Squamous Cell Carcinoma (SCC)
- 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
Bowen’s Disease (SCC in situ)
- 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
Basal Cell Carcinoma (BCC)
- 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
Tinea Capitis
Treatment
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
Lichen Sclerosus
- 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
What are the common autoimmune blistering diseases?
Dermatitis Herpetiform
Bullous Pemphigoid
Pemphigus Vulgaris
Pemphigous Vulgaris
- an autoimmune mucocutaneous blistering disease
- 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
Bullous Impetigo
Blistering condition caused by S. aureus
Bullous Pemphigoid
- autoimmune blistering disease
- pruritic, tense bullae
- flexural surface, groin and axilla, (minority) mucosal lesion
- Biopsy: subepidermal cleavage
- Immunofluorescence: linear IgG deposits at the basement membrane
Dermatitis Herpetiform
- autoimmune dermal reaction to dietary gluten
- 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
Erythema Multiforme
- cell-mediated inflammatory disorder
- erythematous papules and plaques —> target lesions
- A/W HSV
- Biopsy: perivascular lymphocytic infiltrate and epidermal necrosis
Lichen Planus
The diagnosis of LP is based primarily on examination, but biopsy can be performed for confirmation.
Primary Syphilis
Typical presentation
- Single, painless, non-pruritic ulcer with induration (eg. Chancre)
- Bilateral, non-tender lymphadenopathy
Benign Neonatal Rash
Examples?
Usually do not require any treatment - just observation
- Erythema Toxicum Neonatorum
- Milia
- Milaria Rubra
- Neonatal Pustolosis Melanosis
- Neonatal Cephalic Pustulosis
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?
Acanthosis nigricans
Most common cause (insulin resistance): simple obesity, may be due to drug-induced or internal malignancy, (sometimes) idiopathic
Recurrence of genital wart after a course of cryotherapy one year ago
Management
Best: wart removal using physical ablation therapy
Recurrence rate is higher with medical therapy > surgical management
Multiple Symmetrical Subcutaneous Lipomas
- benign tumours of mature fat cells
- common, found in subcutaneous tissue
- usually have positive family history
Desmoid Tumours
- arise from deeper layers of abdominal wall
Epidermoid Cyst
- 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
Neurofibromatosis Type 1
Von Recklinghausen disease
- cafe-au-lait spots, pedunculated and sessile skin lesions (molluscum fibrosum)
Highest risk factors for developing melanoma
Keratochantoma is often confused with…?
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.
Tinea Versicolour
- Cause: Malassezia furfur
- well-demarcated macular rash, hyper/hypopigmented, slightly itchy
- Commonly seen: upper trunk / whole trunk, neck and even upper limbs
Typical tinea Infection
- Cause: dermatophytes
Annular or arcuate
Scaly and itchy
Definite edges and central clearing as it expand
Alopecia Areata
- 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
Lipomas
Site
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)
Mucoid Cyst
Bluish glistening colour, dome-shaped
- obstructed mucoid salivary gland
- incise if persistent or bothersome
Nail Apparatus Melanoma (Subungual Melanoma)
- 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
Oral Candidiasis (Thrush)
- 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
Skin malignancy that will most likely arise from a burn scar
Squamous Cell Carcinoma
Marjolin’s ulcer (less common type of SCC) - found on extremities on chronic ulcers/burn scars
