Dermatology Flashcards
Difference between SJS + TEN
SJS < 10% BSA epidermal detachment
SJS/ TEN overlap 10-30% BSA
TEN > 30% BSA
Definition of DRESS: drug reaction with eosinophilia and systemic symptoms
Drug induced syndrome of rash, fever, lymphadenopathy, haematologic abnormalities, hepatitis
Most often reported with anticonvulsants, NSAIDS + antibiotics. Usually weeks after commencement.
Associated with HHV6 + 7 reactivation
Lack of severe mucosal involvement distinguishes from SJS / TEN
How do you confirm the diagnosis of HSP?
Skin biopsy which shows positive IgA antibodies on immunofluorescence
Causes of palpable purpura
Vasculitis
Infection- meningococcaemia
Hypersensitivity- medication particularly antibiotics + NSAIDs
Immune mediated- lupus, dermatomyositis, Churg-Strauss / Wegner
Differentiating features of HSV vs. varicella
Monomorphic
Lesions are all the same age of evolution
Lesions bunch together
Describe pyogenic granuloma
Common skin growth presents as a shiny red mass
‘Granuloma telangiectaticum’ or ‘lobar capillary angioma’
Benign, cause discomfort and profuse bleeding
Causes of lens dislocation
Most common is trauma
Superior dislocation- Marfan’s
Inferior dislocation
- Homocystinuria (fair hair + developmental delay)
Clinical sign of optic atrophy
Macula is > 2.5 optic discs away from the optic disc!
Causes of unilateral red eye
Foreign body Herpes infection- dendritic ulcer (stain with fluoresin) Glaucoma Iritis Conjunctivitis- only by exclusion
The P’s of candidiasis
The P’s
- Paediatric (if <1yr okay)
- Penicillin use
- Pregnancy
- Pill use
- Parturition
- Prednisone use
If not ‘p’ associated then need to exclude serious pathology such as:
- Diabetes
- Immune suppression
- Malignancy
- Drugs
Treatment of cradle cap ‘seborrheic dermatitis’
Cold pressed oil
1% hydrocortisone
What cell will be seen on microscopy with erythema toxicum?
Eosinophils
Involution of haemangioma % at 5 yrs + 9yrs
60% involution at 5yrs
95% involution at 9yrs
What syndromes are associated with segmental haemangiomas?
PHACE Posterior fossa abnormalities Haemangiomas Arterial anomalies Cardiac + coarctation Eye + endocrine Sternal cleft, supra-umbilical raphae
Sturge-Weber
What virus is erythema multiforme MOST commonly associated with?
HSV
What HLA is DRESS associated with?
HLA-A 3101
What HLA is SJS associated with?
HLA-B1502
What antibody is associated with pemphigus vulgaris + what is the most common site of ulcers?
Desmoglein III
Oral cavity
What is Nikolsky’s sign?
Lateral pressure causes dislodgement of epidermis
Characteristics of eczema herpeticum
The blisters are monomorphic, i.e. they all appear similar to each other.
They may be filled with clear yellow fluid or thick purulent material.
They are often blood-stained i.e., red, purple or black in colour.
New blisters have central dimples (umbilication).
They may weep or bleed.
Older blisters crust over and form sores (erosions).
What cells + cytokines play a prominent role in eczema?
T-lymphocytes play a prominent role in eczema. T cells tend to be chronically stimulated and have increased cell turnover.
In eczema, the number of CD4+ cells is increased, and CD8+ cells are decreased in peripheral blood.
Eczema is also associated with a Th2 cytokine profile
Characteristics of Sturge-Weber syndrome
Sporadic vascular disorder
Seizures
Trigeminal distribution of port wine stain
Unilateral weakness (usually opposite side to port wine lesion)
Retardation (developmental delay)
Glaucoma
Bupthalmos of the ipsilateral eye
NOT all children with a port-wine stain have SWS
Biopsy features of;
Vasculitic lesions
SSSS
SJS
TEN
Vasculitic lesions
- Granular layer with a perivascular lymphocytic and neutrophilic infiltrate
SSSS
- Granular layer with no inflamm cell infiltrate
SJS
- Subepidermal layer with full thickness epidermal necrosis
TEN
- Subepidermal layer with intense perivascular and interstitial mononuclear cell infiltrate
Phimosis vs. paraphimosis
Phimosis refers to the inability to retract the prepuce. At birth, phimosis is physiologic. Over time, the adhesions between the prepuce and glans lyse and the distal phimotic ring loosens. In 90% of uncircumcised males the prepuce becomes retractable by the age of 3 years.
Paraphimosis occurs when the foreskin is retracted past the coronal sulcus and the prepuce cannot be pulled back over the glans. Painful venous stasis in the retracted foreskin results. with oedema leading to severe pain and inability to reduce the foreskin . Treatment includes lubricating the foreskin and glans and then simultaneously compressing the glans and placing distal traction on the foreskin to try to push the phimotic ring past the coronal sulcus.
Incontinetia pigmenti diagnostic criteria
Major criteria
- Typical neonatal vesicular rash with eosinophilia; (in most cases cutaneous manifestations are present at birth)
- Typical blaschkoid hyperpigmentation on the trunk, fading in adolescence; - Linear, atrophic hairless lesions.
Minor criteria
- Dental anomalies,
- Alopecia,
- Wooly hair
- Abnormal nails
Risk of allergic disease / atopy
- 1 parent allergic
- 2 parents allergic
- > 2 first degree relatives allergic
The risk of allergic disease/atopy in a child approaches 50% when one parent in allergic and 66% when both parents are allergic. In families with more than two allergic first degree relatives, 67% of children had an allergic disease/atopy.
Mechanism of action of pimecrolimus
Pimecrolimus is anti-inflammatory. It inhibits calcineurin thus blocking T cell proliferation and preventing release of inflammatory cytokines.
Adverse effects include:
Common: local irritation, burning sensation, itch, erythema, skin infections
Infrequent: local rash, aggravation of eczema, herpes simplex dermatitis, impetigo
Rare: alcohol intolerance (facial flushing, rash, burning sensation), allergy (eg urticaria, angioedema)
In contrast with topical steroids, pimecrolimus does not produce skin atrophy.
What is pyoderma gangrenosum?
Inflammatory skin disease often (~50%) associated with underlying systemic disorders such as inflammatory bowel disease, arthritis, and lymphoproliferative disorders.
As an example, pyoderma gangrenosum occurs in up to 5% of patients with ulcerative colitis and 2% of those with Crohn’s disease. Among patients with inflammatory bowel disease, PG may parallel the activity of the bowel disease.
The eruption may begin as an isolated pustule or scattered lesions on the trunk or extremities. There is surrounding oedema and purplish induration with rapid progression into a large ulcer which heals ultimately with cribiform scars.
What is neonatal pustulosis melanosis and what cell is involved?
Benign self-limiting rash
Present at birth or shortly after with pustular lesions, neonate is otherwise well
Pustules resolve spontaneously but may leave areas of hyperpigmentation
More common in dark skinned children
Microscopic examination reveals neutrophils with no associated organisms
What cell is involved in erythema toxicum?
Eosinophils
Occurs in 50% of term babies
Zinc deficiency risk factors + clinical presentation
Zinc deficiency occurs rarely in exclusively breast-fed infants (usually premature) whose mothers have a low level of zinc in their breast milk. The clinical presentation is similar to that of acrodermatitis enteropathica.
Zinc is an essential mineral i.e. needs to be obtained from the diet as cannot be synthesised in the body. One of the causes of zinc deficiency is excessive losses in intestinal illnesses as malabsorption occurs and diarrhoea results in excessive losses of zinc.
In this case the mother has extensive Crohns disease and so is likely to have zinc deficiency hence her breastmilk will have low levels of zinc. Cases of zinc deficiency during breast-feeding are accompanied by skin rashes or dermatitis which are the main symptoms, often in combination with failure to thrive, low serum zinc and irritability.
Numerous signs and symptoms have been associated with zinc depletion.
Mild zinc deficiency is associated with depressed immunity, impaired taste and smell, onset of night blindness, and decreased spermatogenesis.
Severe zinc deficiency is characterised by severely depressed immune function, frequent infections, bullous pustular dermatitis, diarrhea, and alopecia.
The skin changes are the most distinctive manifestations. These usually consist of dry scaly eczematous placques, often on the face and anogenital area; the lesions often resemble psoriasis.
What is the other term for blueberry muffin spots?
Extramedullary erythropoiesis
Causes of blueberry muffin spots
Tumours such as: Congenital leukaemia cutis Langherhans cell histiocytosis Neuroblastoma Congenital rhabdomyosarcoma
Blood disorders such as:
Haemolytic disease of the newborn – rhesus or ABO incompatibility
Hereditary spherocytosis
Twin-twin transfusion syndrome
Congenital infections such as: Rubella Toxoplasmosis Cytomegalovirus Herpes simplex Coxsackie virus Parvovirus Epstein Barr virus Syphilis
