Passmed Dermatology Mushkies Flashcards
What is a common and benign condition characterised by the development of a painful nodule on the ear?
Chondrodermatitis nodularis helicis (CNH)
What are some things that cause chondrodermatitis nodularis helicis (CNH)?
- Persistent pressure on ear
- Trauma
- Cold
How does one manage chondrodermatitis nodularis helicis?
- Reducing pressure on ear (foam ear protectors)
- Cryotherapy/steroid injection/collagen injection
- Surgical Rx, but high recurrence rate
What does CNH stand for?
Chondrodermatitis nodularis helicis
What are some differential diagnoses for shin lesions?
- Erythema nodosum
- Pyoderma gangrenosum
- Pretibial myxoedema
- Necrobiosis lipoidica diabeticorum
How does one describe erythema nodosum?
Symmetrical, erythematous, tender nodules which heal without scarring
What are the most common causes of erythema nodosum?
- NO = idiopathic
- Drugs = penicillin/sulphonamides
- OCP/Pregnancy
- Sarcoidosis/TB
- UC/CD/Behcets
- Micro = Streptococcus, mycoplasma, EBV
- Malignancy/lymphoma
What are 3 drugs that can cause erythema nodosum?
- Penicillins
- Sulphonamides
- OCP
How does one describe pretibial myxoedema?
Symmetrical, erythematous lesions seen in Graves disease
What are the SBA buzzwords for pretibial myxoedema?
Shiny, orange peel skin
How does one describe pyoderma gangrenosum?
A small red papule that develops into deep, red, necrotic ulcers with a violaceous border
What are some causes of pyoderma gangrenosum?
- Idiopathic = 50%
- IBD
- CTD
- Myeloproliferative disorders
How does one describe necrobiosis lipoidica diabeticorum?
Shiny, painless areas of yellow/red skin typically on the shin of diabetics
What other dermatological finding is necrobiosis lipoidica diabeticorum often associated with?
Telangectasia
Where is venous ulceration most typically seen?
Above the medial malleolus
What is the most important investigation for venous ulceration?
ABPI
What is the normal range for ABPI?
0.9-1.2
What ABPI value typically indicated arterial disease?
<0.9
When might you find a pt with arterial disease with ABPI >1.2?
False negative results secondary to arterial calcification e.g. in diabetics
What is the management of venous ulcers?
- Compression bandage, usually four layer
- Oral pentoxifylline, a peripheral vasodilator, improves healing rate
- Flavinoids (small evidence base)
What is the only treatment shown to be of real benefit for rx of venous ulcers?
Compression bandaging
How can one remember the site of ulceration for venous and arterial ulcers?
- vEnous = mEdial
2. Arterial = lAteral
What are risk factors for SCC of the skin?
- Sunlight exposure
- Actinic keratoses and Bowen’s disease
- Immunosuppression
- Smoking
- Long standing ulcers e.g. Marjolin ulcers
- Genetic
What are 2 genetic conditions that predispose to SCC of skin?
- Xeroderma pigmentosum
2. Oculocutaneous albinism
What should the surgical excision margin be for SCCs that are <20mm in diameter?
4mm
What should the surgical excision margin be for SCCs that are >20mm in diameter?
6mm
What do you call stress ulcers in burns patients?
Curlings ulcers
What is a common result of Curlings ulcers?
Haematemesis
What is a Curling’s ulcer?
Acute gastric erosion from severe burns as reduced plasma volume leads to ischaemia and cell necrosis of gastric mucosa
What is a Dieulafoy lesion?
Large, single, tortuous arteriole in stomach submucosa that erodes and bleeds, but can also present anywhere in GI tract.
How do you manage burns causes by heat?
- Remove person from source
- Irrigate with cool (not iced) water for 10-30 mins
- Cover burn using cling film
How do you manage electrical burns?
Switch off power supply, remove person from the source
How do you manage chemical burns?
Brush off any powder, irrigate with water
What are 3 ways you can assess the extent of a burn?
- Wallace’s rule of Nines
- Lund and Browder chart
- Palmar surface area method
What is Wallace’s rule of Nines for burns?
- Head + Neck = 9%
- Arm = 9%
- Anterior leg = 9%
- Posterior leg = 9%
- Anterior chest = 9%
- Posterior chest = 9%
- Anterior abdomen = 9%
- Posterior abdomen = 8%
- Yeah kan do
What is the most accurate method for assessing the extent of a burn?
Lund and Browder chart
What is the Palmar surface area method for assessing burns?
- Palmar surface = roughly 1% of TBSA
2. Not accurate for burns >15% TBSA
What is the histology and appearance of a 1st degree burn?
- Superficial epidermal
2. Red and painful
What is the histology and appearance of a 2nd degree burn?
- Superficial dermal /deep dermal (partial thickness)
2. Pale pink, painful, blistered/white and reduced sensation
What is the histology and appearance of a 3rd degree burn?
- Full thickness
2. White/brown/black, no blisters, no pain
When are IV fluids indicated for burns?
- > 10% TBSA in children
2. >15% TBSA 2nd/3rd degree burns in adults
What is the formula used for fluid given in burns pts?
Parkland formula
What is the Parkland formula?
Volume of fluid = TBSA x weight in kg x 4
How much of the calculated fluid requirement in a burns pt should be given in the first 8 hours?
Half
What do you call the tough leathery tissue remaining after a full-thickness burn?
Eschar
What is an escharotomy?
Surgical procedure used to treat full-thickness (3rd degree) burns
What is the rationale behind an escharotomy?
Following a full-thickness burn, as the underlying tissues are rehydrated, they become constricted due to the eschar’s loss of elasticity, leading to impaired circulation distal to the wound. An escharotomy can be performed as a prophylactic measure as well as to release pressure, facilitate circulation and combat burn-induced compartment syndrome
When is an escharotomy typically used?
- Circumferential burns affecting a limb
2. Severe torso burns impeding respiration
Is there any evidence to support the use of Abx prophylaxis/topical Abx in burns pts?
No
What is a Marjolin’s ulcer
An aggressive ulcerating SCC presenting in an area of previously traumatised, chronically inflamed, or scarred skin
What is a midline swelling lined by squamous epithelium and hair follicles likely to be?
Dermoid cysts
Why are dermoid cysts typically located in the midline?
They are embryological remnants
What kind of tumour is also referred to as aggressive fibromatosis?
Desmoid tumour
Where do desmoid tumours typically arise?
In ligaments and tendons
What is the most common form of skin cancer?
BCC
Where do BCCs typically occur?
Sun exposed sites apart from the ear
What are 4 subtypes of BCCs?
- Nodular
- Morphoeic
- Superficial
- Pigmented
What is the growth of BCCs like?
Typically slow growing with low metastatic potential
What is the management of a BCC?
Surgical excision, topical chemotherapy and radiotherapy are all successful
What is the treatment of choice for SCCs?
Wide local excision
How can one classify the main diagnostic features for malignant melanoma?
- Major criteria
2. Minor criteria (secondary features)
What are the major criteria for diagnosis of malignant melanoma?
- Change in size
- Change in shape
- Change in colour
What are the minor criteria for diagnosis of malignant melanoma?
- Diameter >6mm
- Inflammation
- Oozing/bleeding
- Altered sensation
How should one manage lesions that are suspicious and may be a malignant melanoma?
Excision biopsy, followed by further re-excision of margins once diagnosis is confirmed by pathology report
What are the margins of excision of a malignant melanoma, with regards to Breslow thickness?
- 0-1mm = 1cm
- 1-2mm = 1-2cm
- 2-4mm = 2-3cm
- > 4mm = 3cm
What is Kaposi’s sarcoma?
A tumour of vascular and lymphatic endothelium, associated with immunosuppression from e.g. HIV
What does Kaposi’s sarcoma look like?
Purple cutaneous nodules
What is dermatitis herpetiformis?
Autoimmune blistering skin disorder, associated with Coeliac disease
What is a dermatofibroma?
A benign lesion consisting of histiocytes, blood vessels and fibrotic changes
How do dermatofibromas present?
Firm elevated nodules, usually with a history of trauma
What are pyogenic granulomas?
Red nodules that are a overgrowth of blood vessels, that usually follow trauma
What other skin lesion do pyogenic granulomas mimic?
Amelanotic melanomas
What is acanthosis nigricans?
Brown to black, poorly defined, velvety hyperpigmentation of the skin
Where is acanthosis nigricans typically found?
In body folds
What is the most common cause of acanthosis nigricans?
Insulin resistance
What is the pathophysiology of acanthosis nigricans?
Insulin resistance –> raised circulating insulin levels –> insulin spillover into skin –> hyperplasia of skin
What do you call acanthosis nigricans in the context of a malignant disease?
Acanthosis nigricans maligna, is a paraneoplastic syndrome
What complication are electrical high voltage burns associated with and thus what is the treatment?
Rhabdomyloysis –> ATN –> Aggressive IV fluids
What virus causes molluscum contagiosum?
MCV
What family of viruses is molluscum contagiosum found in?
Poxviridae
How is molluscum transmitted?
- Directly = close personal contact
2. Indirectly = fomites e.g. shared towels
In what population do the majority of cases of molluscum occur?
In children (often with atopic eczema), max. incidence in preschool children aged 1-4 years
How can one describe molluscum?
Pinkish/pearly white papules with a central umbilication, up to 5mm in diameter
Where on the body does molluscum not appear?
Palms of hands and soles of feet
In children, where are molluscum lesions commonly seen?
Trunk and flexures, but anogenital lesions can also occur
How can one manage molluscum?
- Self care measures
2. Treatment measures
What are some self care measures for molluscum?
- Reassure it is self-limiting
- Spontaneous resolution within 18m
- Avoid sharing towels
- Dont scratch
- Exclusion from school/swimming/gym is not required
What are some treatments for molluscum?
- Cryotherapy
2. Squeezing/piercing
When should molluscum be referred?
- HIV-positive
- Eyelid-margin/ocular lesions
- Adults with anogenital –> GUM for other STI screening
What is used to treat pityriasis versicolor?
Ketoconazole shampoo
What is pityriasis versicolor?
A superficial cutaneous fungal infection caused by Malassezia furfur
What does pityriasis versicolor look like?
Hypopigmented/pink/brown, may be more obvious following a suntan, scale is common, mild pruritis
Where does pityriasis versicolor typically occur?
Trunk
What is the pathophysiology of dermatitis herpetiformis?
Deposition of IgA in the dermis
What are the features of dermatitis herpetiformis?
Itchy, vesicular skin lesions on the extensor surfaces (e.g. elbows, knees, buttocks)
How does one diagnose dermatitis herpetiformis?
Skin biopsy
What does one see on skin biopsy of dermatitis herpetiformis?
Direct immunofluorescense shows deposition of IgA in a granular pattern in the upper dermis
What is the management of dermatitis herpetiformis?
- Gluten-free diet
2. Dapson
What is pityriasis rosea?
An acute, self-limiting rash which tends to affect young adults
What is the aetiology of pityriasis rosea?
Not fully understood, herpes hominis virus 7 (HHV-7) may play a role
What are the features of pityriasis rosea?
- Recent viral infection
- Herald patch on trunk
- Followed 1-2 weeks later by erythematous, oval, scaly patches which follow a characteristic distribution with the longitudinal diameters of the oval lesions running parallel to Langer’s lines
What condition has a ‘fir-tree’ distribution?
Pityriasis rosea
What is the management of pityriasis rosea?
Self-limiting, usually disappears after 6-12 weeks
What is the main differential to consider for pityriasis rosea?
Guttate psoriasis
What are the features of guttate psoriasis?
- Strep sore throat 2-4 weeks earlier
2. Tear-drop scaly papules on trunk and limbs
What is the management of guttate psoriasis?
- Most resolve spontaneously within 2-3m
- Topical agents as per psoriasis
- UVB phototherapy
- Tonsillectomy may be necessary with recurrent episodes
What is the gold standard for management of morphoeic BCC?
Mohs micrographic surgery
What are some topical chemotherapies that can be used for treatment of BCC?
Imiquimod, Fluorouracil
What are some factors that may exacerbate psoriasis?
- Trauma
- Alcohol
- Steroid withdrawal
- Drugs
What drugs can exacerbate psoriasis?
- BBs
- Lithium
- Antimalarials
- NSAIDs
- ACEi
- Infliximab
What can be used for the treatment of mild actinic keratoses?
Topical diclofenac
What are actinic/solar keratoses?
A common premalignant skin lesion that develops as a consequence of chronic sun exposure
What are features of actinic keratoses?
- Small, crusty/scaly lesions
- May be pink/red/brown/skin colour
- Typically on sun-exposed areas
- Multiple lesions may be present
What are the management options for actinic keratoses?
- Sun avoidance and sun cream
- FU cream (2-3wk course)
- Topical diclofenac (if mild)
- Topical imiquimod
- Curettage and cautery
- Cryotherapy
When can a child with impetigo return to school?
When they are no longer contagious =
- When all lesions have crusted over
- 48hr after treatment starts
What is impetigo?
A superficial bacterial skin infection usually caused by either S. aureus or S. pyogenes
How is impetigo transmitted?
- Direct contact with discharges from the scabs of an infected person
- Indirect via toys, clothing, equipment and environment
What are the key features of impetigo?
Golden, crusted skin lesions typically found around the mouth
How can you classify management of impetigo?
- Limited, localised disease
2. Extensive disease
What is the management of limited, localised impetigo?
- Topical fusidic acid first line
- Topical retapamulin second line
- Topical mupirocin if MRSA
What is the management of extensive impetigo?
- Oral flucloxacillin
2. Oral erythromycin if penicillin-allergic
What is acne vulgaris?
- A common skin disorder which usually occurs in adolescence
- Typically affects the face, neck and upper trunk
- Is characterised by the obstruction of pilosebaceous follicles with keratin plugs which results in comedones, inflammation and pustules
How can you classify acne?
Mild, moderate and severe
What is mild acne?
Open and closed comedones with or without sparse inflammatory lesions
What is moderate acne?
Widespread non-inflammatory lesions and numerous papules and pustules
What is severe acne?
Extensive inflammatory lesions, which may include nodules, pitting and scarring
What is the step-up management of acne?
- Single topical therapy
- Topical combination therapy
- Oral Abx
- COCP
- Oral isotretinoin
What are single topical therapies used for acne?
Topical retinoids and benzoyl peroxide
What are some topical combination therapies used for acne?
Topical retinoid, benzoyl peroxide, topical abx
What is the abx management of acne?
- Tetracyclines = lymecycline/doxycycline/oxytetracycline
2. Erythromycin in pregnancy
When should tetracyclines be avoided for tx of acne?
- Pregnant/breastfeeding women
2. Children <12y/o
What is the maximum length of time a single oral antibiotic should be used for acne vulgaris?
3m
What should always be co-prescribed with oral abx for acne and why?
Topical retinoid/BP, to reduce the risk of abx resistance
Should topical and oral abx be used in combination?
No
What may occur as a complication of long term abx treatment of acne?
Gram negative folliculitis
What abx is effective for management of gram negative folliculitis after long term abx tx of acne vulgaris?
High dose oral trimethoprim
What is a c/i to topical and oral retinoid treatment?
Oral isotretinoin, only under specialist supervision
Is there a role for dietary modification in pts with acne?
Supposedly not
How can you describe lichen planus?
- 4Ps = Purple, pruritic, papular, polygonal rash on the flexor surfaces
- Wickham’s striae over the surface
- Oral involvement in 50%
- Koebner phenomenon
- Nails = thinning of nail plate, longitudinal ridging
What are Wickham’s striae?
Whitish lines visible in the papules of lichen planus and other dermatoses, typically in the oral mucosa
How can you describe lichen sclerosus?
Itchy white spots typically seen on the vulva of elderly women
What is lichen planus?
A skin disorder of unknown aetiology, most probably being immune-mediated
What are 3 causes of lichenoid drug eruptions?
- Gold
- Quinine
- Thiazides
What is the management of lichen planus?
- Topical steroids are mainstay
- Benzydamine mouthwash or spray is recommended for oral lichen planus
- Extensive lichen planus may require oral steroids or immunosuppression
Despite being called ‘ringworm’ what is the actual cause of ringworm?
Caused by a group of fungi called dermatophytes
What is tinea?
A term given to dermatophyte fungal infections
What are the 3 main types of tinea (anatomical)?
- Tinea capitis
- Tinea corporis
- Tinea pedis
What is a cause of scarring alopecia, mainly seen in children?
Tinea capitis
What may form if tinea capitis is left untreated?
A kerion
What is a kerion?
A raised, pustular, spongy/boggy mass formed due to untreated tinea capitis
What are the most common causes of tinea capitis?
- Trichophyton tonsurans most common
2. Microsporum canis
How does one acquire microsporum canis?
From cats and dogs
What is the management of tinea capitis?
- Topical ketoconazole shampoo for first 2 weeks
- Tricophyton tonsurans –> terbinafine
- Microsporum canis –> griseofulvin
What are the main causes of tinea corporis?
- Tricophyton rubrum
2. Trichophyton verrucosum
How does one acquire tricophyton verrucosum?
From contact with cattle
How does one treat tinea corporis?
Oral fluconazole
How can one differentiate between Tricophyton tonsurans and Microsporum canis?
Woods lamp –> Trichophyton does not readily fluoresce, Microsporum does
What may topical corticosteroids cause in pts with darker skin?
Patchy depigmentation
What is melasma?
Hyperpigmented brown/grey macules and patches, usually occurs in pregnancy women
What are some risk factors for melasma?
- Darker skin
- Sun exposure
- NSAIDs
- OCP/HRT
What is an example of a mild topical steroid?
Hydrocortisone 0.5-2.5%
What are 2 examples of a moderate topical steroid?
- Betamethasone valerate 0.025%, a.k.a Betnovate RD
2. Clobetasone butyrate 0.05%, a.k.a Eumovate
What are 2 examples of potent topical steroids?
- Fluticasone propionate 0.05%, a.k.a Cutivate
2. Betamethasone valerate 0.1% a.k.a Betnovate
What is an example of a very potent topical steroid?
Clobetasol propionate 0.05% (Dermovate)
What is betamethasone valerate aka?
Betnovate
What is Clobetasone butyrate aka?
Eumovate
What is Clobetasol propionate aka?
Dermovate
What is the finger tip rule?
1 FTU (finger tip unit) = 0.5g, sufficient to treat a skin area about twice that of the flat of an adult hand
What usually precipitates guttate psoriasis?
A streptococcal throat infection