p53 Protein expression in nevi and melanomas

Area of Science:

• Dermatopathology
• Oncology
• Molecular Biology

Background:

• p53 protein immunohistochemical expression is typically associated with malignancy.
• Melanomas are generally reported as p53 positive, while nevi are considered p53 negative.
• p53 plays roles in DNA repair, apoptosis, and cell cycle regulation.

Purpose of the Study:

• To evaluate p53 immunoreactivity patterns in benign nevi and melanomas.
• To assess the potential diagnostic utility of p53 immunostaining in dermatopathology.
• To investigate discrepancies with existing literature regarding p53 expression in nevi and melanomas.

Main Methods:

• Immunohistochemical analysis of p53 expression using antibodies (PAb1801, PAb240, DO7, CM1).
• Study included 75 benign nevi and 47 melanomas (40 primary, 7 metastatic).
• Quantification of p53-positive nuclei in lesional cells and adjacent epidermis.

Main Results:

• 15% of nevi exhibited p53-positive nuclei, typically in less than 1% of cells.
• 30% of melanomas showed p53-positive nuclei, with varying percentages of positive cells.
• p53 positivity was also observed in epidermal keratinocytes, contradicting literature suggesting nevi are p53 negative.

Conclusions:

• p53 positivity in benign nevi and epidermis complicates its use as a sole diagnostic marker.
• Observed p53 expression patterns in melanomas differ from previous reports.
• Discrepancies may stem from population differences, case selection, or sample handling, limiting p53 immunostaining's diagnostic value in distinguishing nevi from melanomas.