Perifollicular linear projections aid in early diagnosis of facial lentigo maligna

Key takeaways:

• Perifollicular linear projections (PLP) were present in 61.8% of melanomas with a specificity of 96%.
• The presence of PLP in a facial lesion should prompt consideration of lentigo maligna.

The presence of perifollicular linear projections is a new dermoscopic feature that may aid in the early diagnosis of lentigo maligna on the face, according to a study.

“Melanomas on sun-damaged skin, including lentigo maligna (LM), can mimic benign flat pigmented lesions,” Cristian Navarrete-Dechent, MD, a dermatologist from the school of medicine at the Pontifical Catholic University of Chile, and colleagues wrote. “While clinical morphology (ie, naked eye examination) of these lesions can be similar, dermoscopy and reflectance confocal microscopy (RCM) have demonstrated the ability to improve the clinicians’ diagnostic accuracy in differentiating LM from benign lesions.”

According to Navarrete-Dechent and colleagues, a recently described RCM feature of LM is “bulging of the hair follicles.” The authors believe that this feature may correlate with perifollicular linear projections (PLP) seen on dermoscopy, which is a new dermoscopic feature the authors defined as “short, linear, pigmented projections emanating from hair follicles.”

To test this hypothesis, the researchers performed both imaging techniques on 83 consecutive biopsy-proven LMs. Results showed that 21 patients (95% CI, 16.4-36) displayed bulging of hair follicles on RCM, with 18 of these 21 patients also displaying PLP on dermoscopy.

Using this correlation, the researchers then conducted another dermoscopy analysis on 252 lesions. These results showed that PLP was present in 61.8% of melanomas and only 3.9% of lesions with other diagnoses (P < .001).

The sensitivity of PLP for the diagnosis of melanoma was 61.8% (95% CI, 49.9%-72.7%) whereas the specificity was 96% (95% CI, 92.9%-98.4%), positive predictive value was 87% (95% CI, 76.1%-93.4%) and negative predictive value was 85.1% (95% CI, 81.1%-88.2%).

Further, on multivariate analysis, PLP was independently associated with a diagnosis of LM (OR = 26.1; 95% CI, 9.6-71).

According to the authors, PLP may add specificity and sensitivity to the early diagnosis of LM located on the face.

“We suggest that PLP should be part of an updated LM progression model,” Navarrete-Dechent and colleagues wrote, adding that PLP should be considered as an intermediary step between the first findings of asymmetric follicular pigmentation and the early annular-granular pattern.