Lichenification

Lichenification is thickening of the epidermis with accentuated skin markings caused by chronic rubbing or scratching. It is the clinical hallmark of lichen simplex chronicus and chronic eczema, and arises from the itch scratch cycle.

• Underlying causes: atopic dermatitis, contact dermatitis, scabies, insect bites, xerosis, stasis dermatitis, psychological stress, anxiety, iron deficiency, renal or hepatic itch, thyroid disease, lymphoma, neuropathic itch.
• Common sites: nape of the neck, ankles, wrists, forearms, scrotum, vulva, shins.

Well defined thickened plaques with exaggerated skin lines, scale, excoriation and altered pigmentation, intensely itchy, worse at night or when stressed.

• Differential diagnosis: psoriasis, lichen planus, tinea, Bowen disease, mycosis fungoides, amyloidosis (macular or lichen), prurigo nodularis, neurodermatitis, scabies, hypertrophic lichen planus.
• Complications: secondary bacterial infection, scarring, pigment change, sleep loss, depression and anxiety, sexual dysfunction in anogenital disease, malignant change rarely.

Clinical; look for the primary cause.

• Skin scraping for scabies and tinea; swab for infection.
• Full blood count, ferritin, renal, liver and thyroid function, glucose, HIV test.
• Biopsy for atypical, resistant or unilateral plaques to exclude psoriasis, lichen planus, Bowen disease or lymphoma.
• Patch testing for suspected contact allergy.

Break the itch scratch cycle with potent topical steroids and barrier protection, while treating the cause.

• Supportive: keep nails short, cotton gloves at night, cool compresses, emollients, avoid irritants and wool, stress management and cognitive behavioural therapy, habit reversal.
• Pharmacological: clobetasol propionate 0.05 percent ointment once daily for 2 to 4 weeks (face and flexures, use mometasone 0.1 percent for 1 to 2 weeks), then taper to twice weekly; tacrolimus 0.1 percent ointment twice daily for steroid sparing; doxepin 5 percent cream three to four times daily for up to 8 days; capsaicin 0.025 to 0.075 percent cream three to four times daily. Night sedation: hydroxyzine 10 to 25 mg at night or amitriptyline 10 to 25 mg at night. Neuropathic itch: gabapentin 300 mg at night increasing to 300 mg three times daily. Treat infection with flucloxacillin 500 mg four times daily for 7 days.
• Procedures: intralesional triamcinolone acetonide 5 to 10 mg/mL every 4 weeks; occlusive tape or hydrocolloid dressing; phototherapy with narrowband UVB for extensive disease.
• Special groups: pregnancy, emollient and moderate potency steroid, avoid hydroxyzine in first trimester; children, mild to moderate steroids and nail care; elderly, avoid amitriptyline if confusion or urinary retention; anogenital disease, exclude lichen sclerosus and neoplasia.
• Red flags: unilateral isolated plaque not responding after 4 weeks, ulceration, weight loss, generalised itch, atypical anogenital changes, suspected lymphoma.
• Follow-up: review at 2 to 4 weeks; taper steroid, maintain emollients; address mood and sleep.