Lichenisation occurs in which layer of skin-

..Definition of Lichenification With prolonged rubbing or scratching, the outer layer of the skin (the epidermis) becomes hyperophied (overgrown) and this results in thickening of the skin and exaggeration of the normal skin markings, giving the skin a leathery bark-like appearance. The Malpighian layer of the skin is generally defined as both the stratum basale and stratum spinosum as a unit, although it is occasionally defined as the stratum basale specifically,or the stratum spinosum specifically.lichenisation of skin occurs in this layer It is named after Marcello Malpighi. Basal cell carcinoma originates Ref Harrison20th edition pg 2134