Expression of p16 in Hypertrophic Lichen Planus

Area of Science:

• Dermatology
• Oncology
• Molecular Biology

Background:

• Cutaneous squamous cell carcinoma (SCC) arising from hypertrophic lichen planus (HLP) is rare but accounts for most malignant transformations.
• The mechanism of malignant pathogenesis in HLP is unknown, but p16 may play a role, as suggested by similar premalignant conditions.
• This study is the first to examine p16 expression in HLP versus SCC and normal skin.

Purpose of the Study:

• To investigate p16 expression in hypertrophic lichen planus (HLP).
• To compare p16 expression in HLP with cutaneous invasive squamous cell carcinoma (SCC) and normal skin.
• To explore the implications of p16 expression for malignant transformation of HLP to SCC.

Main Methods:

• p16 immunohistochemistry was performed on HLP (n=34), well-differentiated SCC (WDSCC), and normal skin.
• Analysis included the percentage of positive cells, staining intensity (nuclear and cytoplasmic), and distribution patterns.
• Evaluations were conducted by two Board-certified dermatopathologists.

Main Results:

• Both HLP and WDSCC showed significantly increased p16-positive cells compared to normal skin (P < 0.001).
• Cytoplasmic p16 was overexpressed in HLP compared to WDSCC (P < 0.05).
• HLP and WDSCC exhibited basal and suprabasal keratinocyte staining, with weaker superficial staining. WDSCC showed focal cytoplasmic margination.

Conclusions:

• Cytoplasmic p16 overexpression in HLP indicates a potential mechanism for p16-mediated cell cycle dysregulation.
• p16 overexpression is a potential contributor to the malignant transformation of HLP into SCC.
• Further research into p16's role in HLP progression is warranted.