Lichenification

LICHENIFICATION (according to Brocq), or lichenization (according to Besnier; 1891), is a chronic change of the skin, characterized by the thickening of all its constituent parts. The skin appears furrowed, rough, and has a shagreen surface. The usual skin pattern becomes coarse, the normal skin furrows enlarge, becoming deeper and more elevated. As a result of the formation of such furrows, quadrangular, rhomboid, or polygonal loops are obtained, arranged in a regular checkerboard pattern. The skin has a mosaic surface, is sometimes covered with thin scales, and is not as delicate and elastic as normal. Affected areas of the skin sometimes have a normal color; more often, however, their color becomes grayish or brownish; in other cases, the lichenified areas appear discolored. The temperature of lichenified skin is usually lower than the surrounding healthy skin, sometimes by more than 1°. Lichenification of the skin can be observed on various parts of the body and occupies either a small area of skin or a more widespread one; the affected areas are not sharply demarcated from the surrounding skin. Along the periphery of the lichenified area, there is a certain number of polygonal plaques, resembling coalesced and individual papules of lichen planus. The histological picture of lichenified skin changes relatively little compared to its normal structure; hyperkeratosis, acanthosis with corresponding elongation of the papillae, and moderate infiltration of the papillary layer of the dermis are noted. Lichenification can be a primary change; this occurs in cases where it develops on the skin as a result of friction and scratching during pruritus. Lichenification can also be a secondary change in various chronically occurring skin eruptions accompanied by itching. Primary or "pure" (according to the terminology of Darier) lichenification of the skin differs from secondary ("combined") by the presence in the latter of typical elements characteristic of those diseases in which secondary lichenification may appear: papules in lichen ruber planus, psoriatic plaques in psoriasis, etc. In recent years, French authors understand lichenification more broadly and are inclined to include here other skin afflictions that have a similar clinical picture and the same pathogenesis (lichenification circonscrite nodulaire chronique Pautrier-Brocq). Regarding the origin of lichenification, a whole series of factors is significant: chronic trauma—wearing bandages, collars, fluor albus in women (A. Pospelov); age and sex possibly have a known influence. Darier and Brocq advocate for a predisposition to this condition in certain subjects.