RESUMEN
Objective To investigate the correlation of epidermal distribution of lamellar bodies and expression of ceramidase with skin barrier dysfunction in polymorphous light eruption.Methods Forty-seven patients with polymorphous light eruption and 40 healthy volunteers were recruited into this study.Noninvasive instruments were used to measure skin sebum content,transepidermal water loss(TEWL)and water content in stratum corneum in all of the subjects.Then,tissue specimens were obtained from the lesions at sunexposed sites in the patients and normal skin of the healthy volunteers.The ultrastructure and distribution of lamellar bodies were observed with transmission electron microscopy in five lesion and control specimens.Immunohistochemistry was performed to detect the expression of ceramidase in the tissue specimens.Results Compared with the normal skin from healthy volunteers,the lesions from patients showed decreased number of lamellar bodies in the granular layer and prick cell layer with a disorganized arrangement.Ceramidase was positively expressed in 20 lesion specimens and 36 normal control specimens,weakly expressed in 21 lesion specimens and 4 normal control specimens,and negative in 6 lesion specimens; there was a significant difference in the expression of ceramidase between the lesion specimens and normal control specimens(P ＜ 0.01).The lesions also showed high TEWL(34.2191 ± 12.70 vs.16.8350 ± 6.50,P ＜ 0.01),lower water content in stratum corneum(22.7319 ± 8.71 vs.29.4250 ± 5.08,P ＜ 0.01)and similar skin sebum content compared with the normal skin.Conclusions There is a disturbance in the synthesis of ceramide in patients with polymorphous light eruption,which may contribute to the impairment of skin barrier.