Figure 2

The expression of pK in keratinocytes and K20 in Merkel cells and the localization of NF200 in nerve fibres of the lesional human oral mucosa of lichen planus. (a) In lichen planus, the epithelium is thin, and rete pegs are not identified by H&E staining. (b) The basal layer is not intact, and there are numerous lymphocytes with chronic inflammation in the lamina propria (detail of the squared area in a). (c) Keratinocytes are moderately positive for pK. Merkel cells are strongly positive for pK. (d) Only Merkel cells located at the basal layer are positive for K20. (e and f) Compared with the healthy oral mucosa, the lesional oral mucosa of lichen planus is associated with a significantly decreased number of NF200-ir nerve fibres distributed in the lamina propria (asterisks). (g) DRAQ5 is detected in the nuclei of cells of the diseased lichen planus tissue section. NF200-ir nerve fibres and nerve endings associated with the K20-ir Merkel cells are not detected. (h) The lesional oral mucosa of lichen planus is associated with a significantly decreased number of NF200-ir nerve fibres compared with the healthy oral mucosa. Bar: a = 1 mm; b-f = 50 μm; g = 20 µm. bl, basal layer; H&E, hematoxylin and eosin; ir, immunoreactive; K20, cytokeratin 20; lp, lamina propria; NF200, neurofilament 200; ome, oral mucosal epithelium; pK, pan cytokeratin.