Pathogenesis and classification of acquired epidermolytic hyperkeratosis

表皮松解性角化过度症（EH）是各种先天性和获得性皮肤病的独特组织学特征。在一些表现为EU的先天性角化疾病中，角蛋白丝异常涉及K1和K10，已知EU是由K1和K10基因突变引起的。然而，关于获得性EH中角蛋白丝异常的报道很少。持续性光化性表皮松解性角化过度症（PAEH）往往在过度日晒后出现，我们认为这是获得性角化过度症的一种，但角蛋白丝异常尚未报道。本研究的目的是检测角蛋白表达以阐明角蛋白丝异常。在PA中观察到多种角蛋白的表达。免疫细胞化学检测EH，光镜下PAEU EH EH病变中K1、K10阳性。电镜观察到异常聚集的张力原纤维中存在K和K10的强烈阳性反应。结论：PAEH病变聚集性张力原纤维中存在K1和Kl0异常。据推测，PABH中的ELI可能是由于过度日晒导致K1和K10基因突变所致。获得性EH通常与表皮松解性棘瘤有关。然而，研究结果表明PAEH与表皮松解性棘瘤无关。

Epidermolytic hyperkeratosis (EH) is a distinctive histologic feature of various congenital and acquired dermatoses. In some congenital keratinizing disorders manifesting EU, the keratin filament abnormality involves K1 and K10, and it is known that EU arises from mutations in the genes for K1 and K10. However, there are few reports on the abnormalities of keratin filaments in acquired EH.Persistent actinic epidermolytic hyperkeratosis (PAEH), which tends to appear after excessive sun exposure, and which we have suggested is one type of acquired EH, but keratin filament abnormalities have not been reported. The purpose of this study was to examine keratin expression to elucidate keratin filament abnormalities. Expression of various keratins was observed in PA.EH using immunocytochemistry, and positive results were obtained for K1 and K10 in the EH lesion of EH in PAEU with light microscopy. Strong positive reactions for K and K10 were seen in abnormally aggregated tonofibrils with electron microscopy. In conclusion, K1 and Kl0 abnormalities were found in aggregated tonofibrils of PAEH lesions. It is suspected that ELI in PABH may result from mutations in K1 and K10 genes because of excessive sun exposure. Acquired EH is usually involved in epidermolytic acanthoma. Elowever, the findings obtained indicate that PAEH is independent of epidermolytic acanthoma.