Dermatoloy Flashcards
Serum sickness/serum sickness like reaction
- Clinical features
- Time course
- Treatment
- Triggers
Clin ft TRIAD: Rash, fever and polyarthritis.
- Pruritic Rash - urticarial-type lesions (see images below)
Often appearing first in flexural areas and then becoming more generalised
Persist for days in same area (migate more slowly that true urticarial rash)
Lesions gradually expand, and may leave a central area of clearing or slight purpura.
Spare the oral mucosa
- Erythema and oedema of hands and feet is common
- Polyarthritis – acute joint pain, limp, inability to walk
- Fever – true serum sickness > 38.5 vs SSLR low-grade fever
- Lymphadenopathy
- Odema of hands, feet, facial, periorbital region
- Low C3 and C4 (type 3 HS reaction)
Time course: Signs and symptoms of true serum sickness occur 1-2 weeks after first exposure, while SSLRs usually develop after 5 to 10 days.
Treatment: Identification and removal of the causative agent is the key, but note treatment may have been ceased prior to appearance of rash.
- True Serum Sickness TRIGGERS :
• Snake anti-venom, equine and rabbit anti-thymocyte globulin (ATG)
• Monoclonal antibody drugs such as Rituximab are most often implicated.
• Insect stings eg: bees
• Antiserum – rabies and tetanus - Serum Sickness-Like Reaction (SSLRs) TRIGGERS
• Cefaclor and amoxicillin.
• Illnesses
• Immunisations
Reactive arthritis/Reiter’s syndrome
What is it/Cause?
Clinical sx
Ix
Cx
Tx
Aseptic inflammatory polyarthritis that usually follows nongonococcal urethritis (Chlamydia) or infectious dysentery (salmonella); commonly in young men/teenage boys
Classic clinical triad:
- Arthritis (polyarticular, assymmetrical, often lower extremities)
- Conjunctivitis
- Urethritis/cervicitis (may be asymptomatic, or present w haematuria +/- purulent discharge)
Onset of polyarthritis 1-2 weeks following initial infection
Ix: anaemia, elevated ESR/CRP, joint aspirate: very high WCC (neuts), no glucose, no crystals.
Cx: cardiac complications include aortitis, aortic valve insufficiency, complete heart block
Tx: indomethacin (steroids less helpful), doxycycline if chlamydia suspected
Clinical features and causes of reactive arthritis
What is the gene associated?
Viral (chlamydia) and post-Gastro (salmonella) including acute rheumatic fever
- resp, GU and GIT infections in preceding 4 weeks (yersinia, shigella, salmonella, campylobater, mycoplasma, streptococcal, chlamydia and gonnorrhoea)
Features
- Lower limb
- Asymmetric
- OLIGOarthritis (2-4 joints)
- no clinical infx of joint
- may last weeks to months with recurrences over several years
- ANA, RhF neg; may be HLA-B27 pos
pathophys SLE
Type 3 hypersensitivity reaction
Chronic autoimmune disease characterized by polyclonal B cell activation + production of autoantibodies + C’ activation
Diagnostic features of kawasaki disease
Diagnostic criteria = fever persisting for 5 days, plus 4 of 5 criteria
i. Conjunctivitis = bilateral, ‘dry’ or non-purulent, preferentially bulbar in distribution
ii. Lymphadenopathy = cervical, most commonly unilateral, tender, at least one node >1.5cm
iii. Rash = polymorphous, without vesicles, bullae or crusts; occurring in the first few days, involving he trunk and extremities
iv. Lips and oral mucosa changes = intense hyperaemia of lips leading to redness and cracking and/or diffuse erythema or oropharynx; strawberry tongue
v. Extremity changes = hyperaemia and painful edema of hands and feet that progresses to desquamation in the convalescent stage; perineal desquamation frequently associated
Cardiac sequelae of kawasaki disease
Coronary aneurysm (20%), pericardial effusion, CHF and myocardial infarction
-> late changes, rarely occur before day 10
Why you need an echo at baseline and then on follow-up at 6 weeks
Including ECG
Management of Kawasaki disease
- IVIG as single infusion within first 10 days of illness (second dose if not responded to 1st)
- Aspirin daily until follow-up echo at 6 weeks
- Steroids at the commencement of treatment for KD in high-risk patients (a bit controversial)
Scarlet fever
What is it caused by?
Sx
Ix
Mx
- Group A beta haemolytic strep
- Entry point is pharynx
- Follows 2-4 days after streptococcal pharyngitis infection
Clinical features
o Fever, headache, sore throat, rigors, vomiting, anorexia
o Swollen tonsils -> White coated tongue (peels) -> strawberry tongue
o Flushed cheeks with circumoral pallor
o Rough/‘Sandpaper’ rash starting on neck then spreading to rest of body (including face, palms, soles)
Ix
o Throat swab - PCR
o ASOT and anti-DNAse B present
Mx
o Oral penicillin for 10 days (erythromycin if penicillin allergy)
Child p/w history of rhinosinitis, cough and dyspnoea with pulmonary infiltrates and nephritis
What type of vasculitis would you suspect and what ix would you order for diagnosis?
Wegeners vasculitis or ‘granulomatosis with polyangiitis’
- Necrotising vasculitis most prominent in lung and kidneys
- Consider in children with sinusitis, pulmonary infiltrates, and evidence of nephritis
- Clinical manifestations
o Fatigue, weight loss, arthralgia
o Rhinosinusitis
o Resp: Cough and dyspnoea, Pulmonary haemorrhage (haemoptysis), subglottic stenosis
o Proliferative GN, renal failure
o +/- Renal insufficiency, purpura, neurological dysfunction - Investigations
o cANCA (90%) = PR3 ANCA
o Necrotising granulomatous vasculitis on pulmonary, sinus or renal biopsy
o CT – nodules, ground glass opacity, mediastinal lymphadenopathy, cavitatory lesions
Mx
- steroids and cyclophosphamide or biologics
What is this diagnosis?
Young black woman
Claudication in arms and legs with absent peripheral pulses
HTN
Fever, malaise and myalgias
Elevated ESR, elevated Neuts
Takayasau arteritis
- is a large vessel vasculitis (aorta and major branches) = ‘pulseless’ disease
Churg strauss syndrome
Churg-Strauss (former name) = ‘eosinophilic granulomatosis with polyangiitis’
- Small vessel necrotising granulomatosis (allergic granulomatosis) vasculitis
- pANCA pos and neg phenotypes (thus sometimes hard to diagnose!)
- Associated with asthma and eosinophilia, rhinosinusitis, nasal polyposis and pulmonary infiltrates
- Rare in childhood
Polyarteritis nodosum
- Systemic necrotising vasculitis affecting small and medium-sized arteries
- Aneurysms and stenoses form at irregular intervals throughout affected arteries
- Rare in childhood
• Clinical manifestations
- Constitutional symptoms
- Mesenteric arterial inflammation/ischaemia – abdominal pain, weight loss
- Renovascular arteritis – hypertension, haematuria, proteinuria
- Cutaneous – purpura, livedo reticularis, ulcerations, digital ischaemia, painful nodules
- CNS – CVA, TIA, psychosis
- Heart – myocarditis, aneurysms, MI, coronary arteritis
• Ix
- Anaemia, elevtaed WCC
- Incr ESR
- anca NEG
- Biopsy of lesions
HSP
clinical ft
ix
mx
prognosis
- Small vessel vasculitis
- Often preceded by URTI (classically GAS)
4 classic features
- Rash – macular -> purpuric, typically on buttox, extensor surfaces; recurring
- Joint involvmenet – arthritis of hips, knees, ankles
- Abdo pain
- Haematuria – secondary to GN (focal segmental in 80%)
Can also have
- Oedema
- Intussusception – bloody stools*
- Pancreatitis
- Ileus
Ix
- Elevated esr
- IgA incr in 50%
- May have deranged coags nad plts
- non anca small vessel vasculitis
Mx
- Treat suspected infx
- Supportive tx
- Renal bx if severe hTN of incr creatinine
- Use of steroids in abdo pain is controversial and can mask signs of intussusception
Prognosis
- 5-10% progress to chronic renal disease (low albumin is sign of poor prognosis)
Antiphospholipid syndrome
Generation of antiphospholipid antibiodies leading to predisposition towards thrombus formation -> clots/strokes
Associated with SLE
Clinical features
- Arterial and venous thrombi
- Stroke, Epilepsy, migraine
- Budd-chiari syndrome
- Livedo reticularis (lace like red rash on exposure to cold), thrombophlebitis, splinter haemorrhages, fingertip ulcers
RIsk of sjogren syndrome in mother to the newborn
Mothers who are anti-Ro positive (70% of sjogrens) can have infants born with congenital heart block (similar to SLE)
Osteogenesis imperfecta - what is it?
gene mutation
types 1-4
Autosomal Dominant condition featuring fragile bones, dentition due to defective or reduced type 1 collagen
Due to mutations in genes COL1A and COL1A2
4 different types
- 1 is mildest form; most common
- 2 is most severe, often fatal
- 3 is assoc w fractures at birth and severe early hearing loss
- 4 similar to 1
Features
- Skeletal:
- -> scoliosis, kyphosis etc
- -> multiple fractures before puberty
- -> barrel shaped chest, soft skull
- -> bowed legs and arms, joint hypermobility
- -> triangular face, small nose
- -> soft brittle discoloured teeth
- -> short stature
- Skin: loose, thin, smooth skin, easy bruising
- Eyes: blue-grey sclera
- Deafness in 50% from age 20
What is this picture diagnostic of?
Wormian bones -> Osteogenesis imperfecta
Also seen in:
- Craniosynosisis
- Rickets
- “Kinky-hair” Menke’s syndrome
- Hypothyroidism and hypophosphatasia
- Down syndrome
What is this condition?
Osteogenesis imperfecta - blue/grey sclera
