Pathogenesis and classification of acquired epidermolytic hyperkeratosis

表皮松解性过度角化病(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的先天性角化性疾病中，角蛋白细丝异常涉及K1和K10，已知Eu是由K1和K10的基因突变引起的。然而，关于获得性EH角蛋白细丝异常的报道很少，持续性光化性表皮松解性角化过度症(PAEH)是一种获得性EH，我们认为这是一种获得性EH，但角蛋白细丝异常尚未见报道。这项研究的目的是检测角蛋白的表达，以阐明角蛋白细丝的异常。免疫细胞化学染色观察到不同角蛋白在PA.EH中的表达，光镜下可见K1和K10在PAEU的EH病变中呈阳性表达。在电子显微镜下，K和K10在异常聚集的张力原纤维中呈强阳性反应。总之，在PAEH病变的聚集的张力原纤维中发现了K1和K10的异常。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皮瘤有关。结果表明，PAEH与表皮松解性棘皮瘤无关。

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.