扁平苔癬および苔癬様皮疹における反応様式の検討

Abstract

The histological features of lichen planus are hyperkeratosis, hypergranulosis, irregular acanthosis, liquefactions degeneration of the basal cell layer and band like lymphoid cell infiltration in the upper dermis. On the other hand, these histological changes are cosidered as a reaction cutanee against the various etiologies. The subject of this report to study the pattern of the tissue reactions in lichen planus and lichenoid eruptions using the term of lichenoid tissue reactions. The histological studies were carried out on the 22 specimens from 12 cases of lichen plauns, 2 of them being of the oral mucosa and the lip and the 4 specimens from 2 cases of lichenoid eruption due to color developer and hypotensive agents. The results obtained were as follows. Epidermal findings; In the early stage, the epidermis showed slight edematous changes, inter cellular edema, vacuolation of prickel cells and basal cells, and accompanied the involvement of basement membrane. As the disease progressed, liquefactions degeneration of the basal cell layer became more obviously, the prickel cells hypertrophied and the epidermis showed pseudoacanthosis. These changes may be a sign of adaptation to keep the homeostasis of the epidermis against the various detriments such as epidermal nutritional insufficiency and abnormal metabolites produced in the dermal lesions. When the balance was disturbed, the epidermis revealed degenerative changes, atrophy and even necrosis. In the advanced lesions, occasionaly, regeneration of the epidermis was noticed and the epidermis showed true acanthosis and occasionally slight parakeratosis. Hyperkeratosis were distinctive findings of this disease. They were a sign of retention of the epidermal cells resulted from supression of the mitosis which was caused by undernutrition of the epidermis. Dermal findings; In the early stage, nonspecific mild inflammation was noticed in the area of the subpapillaries. The infiltrated cells were polymorphous; a few neutrophils, eosinophils, mast cells and moderate lymphocytes. Typical lesions showed marked dilatation and toutous meadering of the capillaries and dilatation of the lymphcapillaries. They are a sign of microcirculations failure, which is a significant element of the histgenesis of this disease. The continuous microcirculations failure elicite reactive lymphoreticular cell hyperplasia. The process of lichenoid tissue reaction can be assumed as follows. When there is reduction in biological activity of the epidermis as a diathesis, the mild inflammation, which may be a certain allergic reaction in the area of the subpapillary pulls the trigger of microcirculations failure. It elicite hypertrophy, degenerative changes and regeneration of the epidermis. These various changes are intermingled in the same lesion and at the same time. This characteristic tissue reaction may be occured on the basis of lichen diathesis. In two specimens, enlargement of the nerves were observed. Involvement of the nerves may be one of the significant element of lichen diathesis. Lichenoid eruptions due to color developer and hypotensive agents showed the same tissue reactions. Ten specimens from 8 cases of melanosis Riehl were observed histologically. They showed similar process of the reaction to that of lichen planus, but lymphoreticular hyperplasia and toutous meandering of the capillaries were not striking. The degeneration of the collagen were remarkable, in two of them hyaline depositions were observed in the papillary region.