Superficial follicular involvement is a ubiquitous finding in lentigo maligna (LM), according to a recent study. Therefore, when considering treatment options for LM with a depth-dependent modality aiming for tumor clearance, mean and maximum depths of involvement should be considered. Researchers conducted a single-center retrospective study of 100 consecutive cases of surgically excised LM treated from 2013 to 2015. Slide review for cases with residual LM on debulk specimen was performed by a dermatologic surgeon and dermatopathologist to characterize follicular involvement. They found:

• 72 of 100 specimens met inclusion criteria for histopathologic evaluation.
• Follicular involvement was seen in 95.8% of specimens, with a mean 68% of follicles involved in a single specimen.
• The mean depth of intrafollicular growth by lesional melanocytes was 0.45 mm (SD=0.23, range 0.1 mm to 1.1 mm).
• Tumor cells were confined to the infundibular portion of the hair follicle in 60.9% of specimens.