Immunohistochemical Differentiation between Actinic Cheilitis and Lichen Planus of the Lips.

Abstract

BACKGROUND: It is difficult to distinguish between actinic cheilitis and lichen planus histologically, because both types of lesions exhibit variable degrees of epidermal dysplasia and dermal lichenoid inflammation. There is currently no consensus on suitable immunohistochemical markers for distinguishing these 2 conditions.

OBJECTIVE: This study aims to determine histological features and immunohistochemical markers that could be used to differentiate actinic cheilitis from lichen planus.

METHODS: Fifteen cases of actinic cheilitis and 11 cases of lichen planus of the lips were included in the study. Histological changes such as parakeratosis, hyperkeratosis, atrophy, acanthosis, ulceration, necrosis, dermal solar elastosis, degrees of epidermal dysplasia and dermal inflammatory cell infiltration were examined. Verhoeff-van Gieson stained sections were quantified for the degree of elastosis using computer software. The following immunohistochemical markers were stained for: bcl-2, Ki-67, proliferating cell nuclear antigen, indoleamine 2, 3-dioxygenase, matrix metalloproteinase-3, matrix metalloproteinase-9, CD4, CD8, c-kit, and prolyl-4-hydroxylase.

RESULTS: The only histologically appreciable difference between the diseases was the degree of epidermal dysplasia. No differences were observed with respect to solar elastosis using the Verhoeff-van Gieson stain. We found that cell proliferation markers such as proliferating cell nuclear antigen and Ki-67 were more highly expressed in actinic cheilitis than in lichen planus. In addition, the number of c-kit-positive cells observed in actinic cheilitis was significantly higher than in lichen planus. The expression levels of the other tested markers were not significantly different between the 2 diseases.

CONCLUSION: The immunohistochemical markers proliferating cell nuclear antigen, Ki-67, and c-kit may help to differentiate actinic cheilitis from lichen planus of the lips.