Key points in dermoscopic differentiation between lentigo maligna and solar lentigo

Area of Science:

• Dermatology
• Dermatopathology
• Medical Imaging

Background:

• Early-stage lentigo maligna presents diagnostic challenges for dermatologists.
• Differential diagnoses include solar lentigo, seborrheic keratosis, lichen planus-like keratosis, pigmented actinic keratosis, and melanocytic nevus.
• Dermoscopy has improved diagnostic accuracy for pigmented skin lesions over the past two decades.

Purpose of the Study:

• To review and detail dermoscopic key points for differentiating lentigo maligna from other diagnoses.
• To reassess the specificity of these dermoscopic features.

Main Methods:

• Literature review of published works on dermoscopic diagnostic criteria for lentigo maligna.
• Detailed description and analysis of dermoscopic findings.

Main Results:

• Key dermoscopic features for lentigo maligna include asymmetrical pigmented follicular openings, rhomboidal structures, annular-granular structures, and gray pseudo-network.
• Asymmetrical pigmented follicular openings and annular-granular structures are initial findings, progressing to rhomboidal structures.
• Annular-granular structures and gray pseudo-network can also appear in regressive areas of other pigmented lesions, suggesting lower specificity.

Conclusions:

• Asymmetrical pigmented follicular openings and rhomboidal structures appear more specific for lentigo maligna diagnosis.
• Annular-granular structures and gray pseudo-network are less specific, though their distribution may differ.
• Accurate interpretation of dermoscopic features is crucial but can be challenging.