Follicular Involvement is Frequent in Lentigo Maligna: Implications for Treatment

Publication date: Available online 26 September 2018

Source: Journal of the American Academy of Dermatology

Author(s): Karen L. Connolly, Cerrene Giordano, Stephen Dusza, Klaus J. Busam, Kishwer Nehal

Abstract

Background

Follicular involvement of lentigo maligna (LM) is considered a histopathologic hallmark, but its prevalence and characteristics have not been well-defined. The depth of intrafollicular extension by neoplastic melanocytes may have clinical importance in the treatment of lentigo maligna.

Objective

To describe the prevalence and features of follicular involvement in LM, including depth of follicular growth by melanocytes.

Methods & Materials

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.

Results

Seventy-two of 100 specimens met inclusion criteria for histopathologic evaluation. Follicular involvement was seen in 95.8% of specimens (95% CI: 88.3%-99.1%), 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.

Conclusion

Superficial follicular involvement is a ubiquitous finding in LM. When considering treatment options for LM with a depth-dependent modality aiming for tumor clearance, mean and maximum depths of involvement should be considered.