OTHERS Flashcards
What causes scabies?
The mite sarcoptes scabiei and its spread by prolonged skin contact
What age does scabies typically affect?
Children and young adults
Pathophysiology of scabies?
The scabies mite burrows into the skin, laying its eggs in the stratum corneum
The intense pruritus associated with scabies is due to a delayed type 4 hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection
Clinical features of scabies?
Widespread pruritus
Linear burrows on the sides of fingers, interdigital webs and flexor aspects of the wrist
Secondary features due to scratching - excoriations and infection
Management of scabies?
Permethrin 5% is first line - apply to all areas paying close attention to between fingers/toes, under nails, armpit area, creases of skin. Allow to dry and leave on skin for 8-12 hours before washing off. Reapply if washed off during treatment period.
Repeat treatment 7 days later
How long does pruritus last in scabies?
Usually 4-6 weeks post eradication
Advice for household members when scabies is diagnosed?
avoid close physical contact with others until treatment is complete
all household and close physical contacts should be treated at the same time, even if asymptomatic
launder, iron or tumble dry clothing, bedding, towels, etc., on the first day of treatment to kill off mites.
What us crusted scabies?
Aka Norwegian scabies
This is seen in patients with suppressed immunity, especially HIV
The crusted skin will be teeming with hundreds and thousands of organisms
Management of crusted scabies?
Ivermectin
Isolation is essential
Clinical features of lichen planus?
An itchy, papular rash most common on the palms, soles, genitalia and flexor surfaces of arms
Rash is polygonal in shape with white-lines pattern on the surface
Koebner phenomenon may be seen
Oral involvement in 50% of cases - white-lace pattern
Nail changes - thinning of nail plate and longitudinal ridging
What causes lichen planus?
Unknown aetiology, most probably immune-mediated
Drug causes of lichen planus?
Gold
Quinine
Thiazides
Management of lichen planus?
Potent topical steroids
Benzydamine mouthwash or spray for oral lichen planus
If extensive it may require oral steroids or immunosuppression
What is Henoch-schonlein purpura?
An IgA mediated small vessel vasculitis
Usually seen in children following an infection
Clinical features of HSP?
Palpable purpuric rash with localise oedema - over buttocks and extensor surfaces of arms and legs
Abdominal pain
Polyarthritis
Features of IgA nephropathy may occur e.g. haematuria
Management of HSP?
Analgesia if arthalgia
Supportive
Prognosis of HSP?
Excellent - usually a self-limiting condition especially in children without renal disease
Bp and urinalysis should be monitored to detect progressive renal involvement
1/3rd of patients have a relapse
What can cause purpura in children?
Meningococcal septicaemia
ALL
Congenital bleeding disorders
ITP
HSP
Non-accidental injury
Causes of purpura in adults?
ITP
Bone marrow failure e.g. leukaemia or myelodysplasia
Senile purpura
Drugs e.g. anti thrombotic
Nutritional deficiencies e.g. vit B12 or C or folate
What is senile purpura?
Aka actinic purpura
A common benign condition characterised by recurrent purple ecchymoses on extensor surfaces of foreharms following minor trauma
What are keloid scars?
Tumour-like lesions that arise from the connective tissue of a scar and extend beyond the dimensions of the original wound
Predisposing factors for keloid scars?
Ethnicity: dark skin
Young adults
Common sites for keloid scars?
In order of decreasing frequency:
Sternum
Shoulder
Neck
Face
Extensor surface of limbs
Trunk
Treatment of keloid scars?
If early it may be treated with intra-lesional steroids e.g. triamcinolone
Excision is sometimes required but careful consideration is needed for the potential to create further keloid scarring
What is a a thesis nigricans?
Symmetrical brown velvety plaques found often on the neck, axilla and groin