Cutaneous Photoaging: A Notable Pattern of Distribution of Lentigines on the Face

July 2020 | Volume 19 | Issue 7 | Original Article | 755 | Copyright © July 2020


Published online June 18, 2020

Farah A. Moustafa MD,a Abrar A. Qureshi MD MPH,b Jeffrey S. Dover MD FRCPCa,c

aSkinCare Physicians, Chestnut Hill, MA bDepartment of Dermatology, Rhode Island Hospital, Brown Medical School, Providence, RI cDepartment of Dermatology Yale University School of Medicine, New Haven, CT

RESULTS




A total of 191 patients’ charts were screened and 62 met the criteria. The patient cohort had a mean and median age of 57 with a range of 27–78. Of the 62 patients evaluated, there were 52 women and 7 men. Approximately 10% of the cohort had a prior history of a non-melanoma skin cancer. With respect to Fitzpatrick skin types, 3% were skin type I (n=2), 40% skin type II (n=25), 44% skin type III (n=27), and 13% skin type IV (n=8).

The number of facial lentigines in each of 21 units were recorded. A heat map schematic was created by manually plotting each individual lentigo into each of the aforementioned units. (Figure 2).

With regards to individual units, the frontal unit had the greatest number of lentigines with 106 on the left-side and 82 on the right-side (total 188 lentigines). This was followed by the parotid-masseteric unit with 87 on the left-side and 71 on the right-side (total 158 lentigines). The nasal unit had 89 lentigines. Other areas that were noted to have relatively high numbers of lentigines included the temporal, zygomatic, and buccal units (Table 1). The Wilcoxon rank-sum test was applied to assess for a difference in laterality and found the average number of facial lentigines was 7.7 for left facial units and 6.5 on right facial units, however, this was not statistically significant (P=0.20).

Finally, in order to compare the distribution of lentigines as central or peripheral, subunits were categorized as follows: central (nasal, labial, zygomatic, infraorbital, and orbital) and peripheral (frontal, supraorbital, temporal, parotid-masseteric, buccal, and mental). A Wilcoxon-rank sum test was performed to evaluate for a difference between lentigo distribution within the designated central and peripheral subunits. The mean number of lentigines in the central units was 0.60 and in the peripheral units was 0.85. This finding was statistically significant with a P value of 0.0001.

DISCUSSION

The comparisons were analyzed using a Wilcoxon rank-sum given the non-normal distribution of the collected data. Our findings were notable in several key ways. First, in this cohort of patients, lentigines were noted to be more prevalent in the grouped peripheral units than the grouped central facial units (0.85 vs 0.6; P<0.0001). Additionally, it is important to note that although the frontal subunits had the highest absolute number of lentigines, the density appears to be highest in the temporal, zygomatic, and parotid-masseteric units. This is explained by the high number of lentigines in these units, which have small surface areas (especially when compared to frontal subunit, which has the largest surface area). We hypothesize that the reason that lateral facial compartments have more lentigines than central ones is related to sun exposure and behavior. For the most part, unless trying to actively tan, one tends to look away and not directly at the sun. Thus, the lateral face gets more sun exposure that the central face and could explain the difference. Several studies have shown that the most common aesthetic units affected by skin cancer are the nasal, buccal, and temple units.1,2,3,4 In this subset of patients, there was a statistically significant difference in distribution of lentigines with more lentigines in the peripheral cosmetic units. This may be attributed to a number of reasons including differences in biology between lentigines and skin cancer, site-specific biology, and patient behavior. This information is helpful when counseling patients regarding sun protection and prevention of lentigines. Recently published data has shown the rates of skin cancer development on different parts of the face are not associated with the amount of sun exposure as some of the least exposed units (ie, under eyebrow, eyelids, nasolabial folds, and the medial/lateral canthus) had higher rates of skin cancer development than more exposed units (ie, forehead, chin, temple, jaw).2