Melanocytes in nonlesional sun-exposed skin: a multicenter comparative study

Area of Science:

• Dermatopathology
• Histology
• Melanoma Diagnosis

Background:

• Limited data exists on melanocyte density and distribution in sun-exposed head and neck skin.
• Comparisons using hematoxylin-eosin (H&E) and Melan-A staining across geographic populations are lacking.
• This information is crucial for diagnosing lentigo maligna.

Purpose of the Study:

• Characterize melanocyte density and distribution in nonlesional facial and neck skin.
• Compare findings between Florida and Minnesota populations.
• Quantify features mimicking melanoma in sun-damaged skin to prevent overdiagnosis.

Main Methods:

• 100 patients undergoing Mohs surgery enrolled (50 Florida, 50 Minnesota).
• Permanent tissue sections from sun-exposed, nonlesional skin analyzed.
• Melanocyte density and distribution quantified using H&E and Melan-A stains.

Main Results:

• Median melanocytes/HPF: 9 (H&E) and 11 (Melan-A).
• Higher densities observed in Florida vs. Minnesota (H&E).
• Density decreased with age; higher in men (Melan-A). Confluence noted in 24% (H&E) and 45% (Melan-A).

Conclusions:

• High melanocyte density, confluence, focal pagetosis, and cytologic atypia can occur in non-neoplastic sun-damaged skin.
• Awareness of these findings aids appropriate histologic interpretation.
• Prevents potential overdiagnosis and unnecessary treatment of melanoma.