is a form of dermatitis caused by repeated scratching or rubbing, which results in epidermal thickening
Lichen simplex
due to chronic ‘itch-scratch cycle’ – Starting with an initial itch, chronic scratching and/or rubbing causes further itching, creating a vicious circle.
the trigger of which is unrecognized
ie: mosquito, stress, nervous habit etc
following repetitive excoriation and scratching, well circumscribed thickened patches develop
inciting stimulus:
Primary lichen simplex develops on normal skin
Secondary lichen simplex can follow an underlying itchy dermatosis
atopic dermatitis, psoriasis, scabies, xerosis
Neural-mediated stimulus that triggers itch
brachioradial pruritus, radiculopathy
Systemic disease associated with pruritus
uraemia, polycythaemia vera, malignancy
Environmental triggers
heat, sweat, chemical irritants, insect bite.
Clinically
commonly occurs in mid-late adulthood, with the highest frequency in people aged 30–50 yr,
more in women 2:1 ratio.
demarcated, erythematous patches, and plaques of thickened leathery skin
common in neck / scalp / shoulder / wrist + ankle
Pigmentary changes, such as hyper- or hypopigmentation, are more commonly seen in patients with darker skin types; erythema is much less obvious
Differentials
Atopic dermatitis
Psoriasis
Lichen planus
Contact dermatitis
Mycosis fungoides
Superficial basal cell carcinoma, in situ squamous cell carcinoma.
Treatment
Breaking the itch-scratch cycle
Physical barriers and bandaging to reduce subconscious scratching
Emollients — aim for use at least twice daily; best applied after showering to retain moisture.
Providing education
Behavioural changes
Reduce stress
keep nails short
wear loose-fitting clothing.
Avoid and/or address trigger
Medications
First-generation sedating antihistamines (e.g. phenhydramine or chlorpheniramine) for those with disruptive night-time pruritus.
Topical corticosteroids — superpotent topical corticosteroids 1–2x daily with either paste bandage or hydrocolloid occlusion(cling wrap) for up to 4 weeks.
Weaker steroids can be used in sensitive thin skin areas.
Coal tar preparations.
Topical antipruritics — capsaicin or doxepin cream.
Topical calcineurin inhibitors — tacrolimus ointment or pimecrolimus cream
