Derm

Question 1

Incontinentia Pigmenta

Answer 1

• This is typically lethal in males antenatally.
• X-linked In most patients, cutaneous manifestations are present at birth or occur within the first 2 weeks of life. The cutaneous manifestations usually appear in a characteristic, chronologic sequence.
• Other systemic manifestations, including ocular defects, CNS abnormalities, and dental abnormalities, may not be recognised until infancy or early childhood.
• Diagnostic criteria for incontinentia pigmenti have been proposed. In the absence of a family history, the presence of at least 1 major criterion is necessary. The presence of minor criteria supports the diagnosis of incontinentia pigmenti.

Major criteria are: typical neonatal vesicular rash with eosinophilia -typical blaschkoid hyperpigmentation on the trunk, fading in adolescence -linear, atrophic hairless lesions.

Minor criteria are:

• -dental anomalies,
• -alopecia,
• -wooly hair,
• -abnormal nails

With a definitive family history, the presence of any major criterion strongly supports the diagnosis of incontinentia pigmenti.

Question 2

Ichthyosis

Answer 2

– the ichthyosiform dermatoses are a diverse group of hereditary skin disorders characterised by the accumulation of “fish-like” scales resulting from abnormal epidermal cell kinetics or differentiation.

• The severity of the individual disorders ranges from asymptomatic to life-threatening.
• Icthyosis vulgaris – mildest form. Presents during childhood, not apparent in the newborn.
• X-linked icthyosis – affects males, onset at 2-6 weeks of age, worsens with age. Large brown adherent scales.
• Lamellar icthyosis – affected patients present as a “collodian baby” at birth.
• CIE (congenital icthyosiform erythroderma) – also presents as a “collodian baby.”
• Epidermolytic ichthyosis – also known as bullous ichthyosis or bullous CIE. Presents with widespread blistering and erythema.
• Harlequin ichthyosis – the most severe form, often lethal perinatally.

Question 3

SJS/TEN

Answer 3

Severe adverse cutaneous drug reaction characterised by mucocutaneous tenderness, erythema & extensive exfoliation

• SJS <10% BSA detachment
• SJS-TEN overlap: 10-30% BSA detachment
• TEN >30% BSA detachment

Most common triggers:

• NSAIDs
• Antibiotics: sulfonamides, aminopenicillins, cephalosporins
• Anticonvulsants: carbamazepine, phenytoin, lamotrigine
• Checkpoint inhibitors: ipilimumab, nivolumab
• Allopurinol

Onset symptoms 7-21 days after initiation of drug

Aetiology: • In predisposed individuals, immune response to a drug leads to secretion of cytotoxic granulysin plus interaction of Fas-FasL apoptosis of keratinocytes leads to separation of skin at dermal-epidermal junction

Clinical features:

• Prodrome:URTIsx, fever,painful skin, pain on swallowing
• Skin: erythematous–dusky maculesstart on trunk, spread to head/limbs, coalesce casein epidermal detachment
• Mucosa:erythema,erosions, haemorrhagic crusting

HLA types - Carbamazepime HLA B1502 - Allopurinol HLA b5801

Rx • STOP culprit drug/s

• Admit ICU with MDT input • Supportive care • Gentle handling, barrier nursing
• Treat secondary infection
• Fluid/electrolyte management + nutritional support
• Skin + mucosal care: dressings, emollients, eye drops • Systemic treatment – controversial

Question 4

SJS VS TEN VS Erythema multiforme

Answer 4

Question 5

Morbilloform drug reaction

Answer 5

• Most common drug causes: penicillins, cephalosporins, sulfonamides, aromatic anticonvulsants, allopurinol
• Onset typically 7-14 days after initial drug administration
• Symmetrically distributed erythematous macules and papules trunk and proximal limbs - >confluent erythema
• No mucous membrane involvement
• Itch + low-grade fever
• Resolves without sequelae 1-2 weeks
• Viral infection + drug

Question 6

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)

Answer 6

DRESS diagnostic criteria
• Maculopapular rash developing > 3 weeks after drug initiation • Prolonged symptoms after discontinuation of causative drug
• Fever
• LFT abnormalities (ALT 100 U/L) or impaired renal function

• WCC abnormalities:
• Leukocytosis >11 x 109/L
• Atypical lymphocytes >5% • Eosinophilia >1.5 x 109/L

• Lymphadenopathy • HHV-6 reactivation

Commonly implicated drugs:

• Allopurinol
• Anticonvulsants
• Antibiotics – trimethoprim- sulfamethoxazole, minocycline, vancomycin, penicillins
• Antiretrovirals
• Ibuprofen, aspirin
• Onset after drug initiation: 2-6 weeks
• HLA-B*31:01 & carbamazepin

Mx: STOP drug, oral prednisolone tapered over 6-8 weeks

Question 7

HLA typing associated with risk SJS with Carbamazepine

Answer 7

HLA B 1502

Question 8

Fixed drug eruption

Answer 8

Well-defined round-oval erythematous patches -> purple/brown. May blister

Recurs at the same site/s each time drug is administered

• Mucosal & acral sites commonly affected

Onset: 30 minutes to 8 hours after taking drug

Typical agents: paracetamol, tetracyclines, sulfur antibiotics, NSAIDs

Variant: generalised bullous fixed drug

Question 9

Serum sickness-like reaction

Answer 9

Clinical features:

• Fever, arthralgias, arthritis, rash (urticarial, morbilliform), lymphadenopathy
• Onset 1-3 weeks after drug exposure
• Most commonly due to cefaclor (1 in 2000 children)
• Other associated drugs: penicillins, NSAIDs, phenytoin, sulfonamides, minocycline, propranolol

Mx: STOP drug, NSAIDs, antihistamines ?prednisolone

Question 10

HEREDITARY ANGIOEDEMA

Answer 10

Recurrent angioedema without wheals

Pathophysiology:

Types I & II: inadequate levels of functioning C1 inh - > excessive production of bradykinin -> inflammation with leakage of fluid through vessel walls –> oedema

Type III: (20% cases) mutation causes production of Factor XII which has increased activity. –> increased production of bradykininàoedema

Treatment:
• C1 inhibitor

• Icatibant

Question 11

Congenital melanocytic Naevi

Answer 11

Size (projected adult size):

• Small:<1.5cmdiameter
• Medium:1.5-20cmdiameter
• Large/giant:>20cmdiameter

Giant CMN:
• 70%satellitenaevi
• 5-10% neurocutaneous melanosis

• MRI brain/spine(ideally<6/12age)

• Benign proliferative nodules common
• Increased risk of melanoma (CNS or skin)

Question 12

Erythema toxicum neonatorum

Question 13

Congenital pustular melanosis

Answer 13

Onset: birth

Clinical features: pustules without erythema -> collarettes of scale –> hyperpigmented macules (persist

for months). Skin changes can occur any region, including palms/soles

More common in infants of African descent

Diagnostic studies: Wright’s stain:

Question 14

Neonatal cephalic pustulosis

Question 15

Genes in eczematous conditions

• Atopic dermatitis
• Netherons
• Wiskot aldrich
• Hyper IgE
• XL icthyosis

Answer 15

Question 16

Dermatoses

• TS
• NF
• Ataxia telangiectasia
• EB

Answer 16