Allergic contact dermatitis

…Symptoms vary from small blisters, erosions, desquamation, skin thickening, fissures, pigmentation, prurigo, large blisters, and ulcers. Dermatitis can be broadly divided into two types: irritant contact dermatitis (ICD), which occurs when toxic chemicals come into contact with the skin, and allergic contact dermatitis (ACD), which occurs when a rejection reaction to the chemicals that have come into contact is brought about by T lymphocytes, and epidermal cells with antigens attached are killed by killer T cells, liquefied, and form small blisters. As a variation of the latter, there is dermal dermatitis, in which allergens are present in the dermis and cause tuberculin reaction-type swelling and redness, and reaction types such as lichen planus and lichenoid reactions, in which the basal layer of the epidermis becomes the target of attack by T cells and liquefies, and the melanin protein contained therein is scattered to the upper layer of the dermis, causing pigmentation that is difficult to heal. …

*Some of the terminology that refers to "allergic contact dermatitis" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…症状も小水疱，糜爛（びらん），落屑（らくせつ），皮膚肥厚，皹裂（きれつ），色素沈着，痒疹，大水疱，潰瘍などさまざまである。　皮膚炎は大きく分けて，毒性のある化学物質が皮膚に触れて起こる刺激性接触皮膚炎irritant contact dermatitis(ICD)と，接触した化学物質に対する拒絶反応がTリンパ球によってもたらされ，抗原の付着した表皮細胞がキラーT細胞によって殺され，液化されて小水疱を形成するアレルギー性接触皮膚炎allergic contact dermatitis(ACD)の2種類がある。後者の変形として，アレルゲンが真皮内に存在してツベルクリン反応型の腫張，発赤を生ずるdermal dermatitisや，表皮基底層がT細胞の攻撃目標となって液化し，その中に含まれていたメラニンタンパク質が真皮上層にまき散らされて，治りにくい色素沈着を生ずる扁平苔癬（たいせん）～苔癬型反応のような反応型式もある。…

※「allergic contact dermatitis」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報