Prospective Lesion-Level Analysis of the Inverse Approach for Lentigo Maligna in Real-World Clinical Practice

Area of Science:

• Dermatology
• Dermoscopy
• Oncology

Background:

• Lentigo maligna (LM) is a melanoma subtype often found on sun-damaged skin.
• Classic diagnostic criteria can be insufficient for early or subtle LM, potentially due to overlapping features with benign conditions.
• The inverse approach, focusing on the absence of non-melanoma features, offers a new strategy for LM detection.

Purpose of the Study:

• To prospectively assess the real-world effectiveness of the inverse dermoscopic approach in distinguishing LM from mimickers.
• To evaluate the inverse approach's capability in detecting LM lesions that do not meet classic diagnostic criteria.

Main Methods:

• A prospective study involving consecutive patients with pigmented flat lesions on the head and neck.
• Independent assessment of lesions by two dermatologists using both classic and inverse dermoscopic criteria.
• Biopsy confirmation for lesions deemed suspicious by either classic or inverse approach criteria.

Main Results:

• Out of 956 lesions evaluated, 145 were actinic keratosis and the majority were benign.
• Classic criteria identified four suspicious LM lesions, all confirmed histopathologically.
• The inverse approach identified three additional LM cases that were missed by classic criteria, also confirmed by biopsy.

Conclusions:

• The inverse approach successfully identified all LM cases in this cohort, including those with subtle or absent classic criteria.
• This method serves as a practical adjunct for dermoscopic evaluation of pigmented facial lesions.
• Further multicenter studies are recommended for broader validation of the inverse approach.