Background: Lichen planus (LP) is considered to be an immune-mediated disease of a not fully understood etiology. There are scarce data on the immune cells forming the band-like infiltration in cutaneous LP (CLP). The objective of the current study was to investigate the immunohistochemical pattern of cells forming the infiltrate in CLP by assessing the immunoexpression of selected cell lineage markers.
Methods: The immunohistochemical analysis of the expression of CD4, CD8, CD20, CD56, CD68, c-Kit, and Foxp3 was performed in formalin-fixed paraffin-embedded (FFPE) biopsy specimens from 14 cases of CLP and 11 healthy volunteers.
Results: The expression of CD4 (P < 0.001), CD8 (P < 0.001), CD68 (P < 0.001), Foxp3 (P < 0.001), CD56 (v = 0.019), and CD20 (P < 0.001) was significantly higher in lesional skin in CLP compared to healthy controls. The ratio of CD4+ to CD8+ cells in the infiltrate was 1.75:1. The expression of Foxp3, CD56, and CD20 was markedly lower than the expression of CD4 and CD8. There was no statistically significant difference in c-Kit expression between CLP lesions and healthy skin (P = 0.57).
Conclusions: We found a wide variety of immune cells in the inflammatory infiltrate in CLP. The expression of CD4, CD8, CD68, Foxp3, CD56, and CD20 was significantly increased in CLP, while the expression of c-Kit was comparable in lesional skin and controls. The presence of various cell populations, including T regulatory cells, NK cells, and B cells, may indicate a complex pathogenesis of CLP.
© 2021 the International Society of Dermatology.