Benign atypical naevi: diagnostic difficulties and continued controversy

Area of Science:

• Dermatopathology
• Histology
• Oncology

Background:

• Benign melanocytic nevi (moles) present a wide range of histological appearances.
• Certain nevi, like Spitz nevi and halo nevi, are recognized entities due to shared features.
• A diagnostic challenge exists with acquired nevi showing junctional atypia.

Purpose of the Study:

• To explore the histological spectrum of benign melanocytic nevi.
• To address the diagnostic grey area of acquired nevi with atypical junctional activity.
• To clarify the biological significance of these challenging nevi.

Main Methods:

• Histological examination of benign melanocytic nevi.
• Review of recognized nevi entities with specific histological features.
• Analysis of acquired nevi with predominantly junctional atypical activity.

Main Results:

• Benign nevi exhibit diverse histological patterns, including specific entities like Spitz and halo nevi.
• A subset of acquired nevi shows junctional atypia without meeting full criteria for dysplastic nevi.
• The biological significance of these 'ordinary' acquired nevi with mild atypical junctional activity is currently unclear.

Conclusions:

• Benign melanocytic nevi have varied histological presentations.
• Acquired nevi with mild junctional atypia represent a diagnostic challenge with uncertain biological implications.
• Careful evaluation is crucial, especially in older individuals, to avoid misdiagnosing melanoma in situ.