Case history
Case history #1
A 45-year-old woman presents with an intensely pruritic plaque on the ankle. She describes recurring paroxysms of pruritus followed by intense rubbing and scratching resulting in a feeling of satisfaction. The pruritus is most intense at night, and the patient's spouse notes that she often appears to be rubbing at her ankle with the opposite foot while she sleeps. She has an underlying history of depression and has been experiencing increased psychological stress in her life related to a recent illness in the family. She has no prior history of atopic dermatitis or asthma but does have a history of seasonal allergic rhinitis. She has tried to treat the lesion with over-the-counter 1% hydrocortisone cream with no improvement. On examination there is a 4x5 cm violaceous plaque on the left medial ankle. The plaque demonstrates prominent lichenification and overlying shallow erosions consistent with excoriation.
Case history #2
A 6-year-old boy, with a past medical history of atopic dermatitis, presents with persistently pruritic thickened plaques in the antecubital fossae. He recently developed a flare of atopic dermatitis associated with a cold dry winter. His parents report uncontrolled pruritus, especially prominent at night. Typically during flares he responds rapidly to a low-potency topical corticosteroid and increased application of emollients. However, the current plaques have failed to respond to these therapies. On examination there are 2x4 cm erythematous, thickened, lichenified plaques in the antecubital fossae accompanied by erythematous patches in the popliteal fossae and hyperlinear palms.
Other presentations
Other common clinical presentations include involvement of the scrotum (pruritus scroti) or labia majora (pruritus vulvae) characterised by thickened lichenified skin with excoriations and, often, linear fissures at the sites of skinfolds.[2] Altered pigmentation may be prominent, especially in patients with darker skin, who may experience hyperpigmentation or hypopigmented macules.[2] Involvement of the occipital scalp and anus (pruritus ani) is also common.[1][3] Less common presentations include hyperpigmented patches in the interscapular region and hyperpigmented papules on the shins resulting in macular and lichen amyloidosis, respectively.[4][5]
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