Histopathological examination
The paraffin-fixed skin samples were sectioned and stained using
hematoxylin-eosin for pathological examination. Histopathological
anomalies, such as hyperplasia of the epidermis, hyperkeratosis,
inflammatory infiltrates, or epidermal degeneration, were recorded and
scored using a numerical scale. The gross and histological scores of the
lesion samples from Changan and Ningshan were analyzed using the
independent samples T test in SPSS 20.0 (IBM Corp., 2011) because the
quantity of sample from other districts were too small to compare.