Background and aims: The new WHO classification distinguishes 2 main pathogenic pathways for cutaneous melanoma, low and high-chronic sun damage (CSD). However, there are no studies to support its validity in the category of non-acral cutaneous lentiginous melanoma (NACLM). Thus, the aim of this study was to correlate the degree of solar elastosis (SE) with a range of clinicopathologic and genomic parameters in a cohort of NACLMs.

Material and methods: We conducted a retrospective cohort study of patients affected by an in situ or invasive NACLM distributed across 3 groups depending on the grade of SE. NACLM includes lentigo maligna melanoma and lentigo maligna, and other non-acral cutaneous lesions with a lentiginous growth pattern.

Results: The study included a total of 257 patients, 132 men (51.4%) and 125 women (48.6%) with a median age of 71 years. SE grade I was reported in 38 cases (14.8%), grade II in 61 cases (23.7%), and grade III in 158 cases (61.5%). Higher SE grade was related to head/neck location, older age at diagnosis and presence of lentigines in melanoma area. Lower SE grade was related to other locations, higher nevi count, presence of regression and BRAF V600E mutation (univariate logistic regression quantification: V600E vs WT; OR, 0.23; 95%CI, 0.05–1.06; p = 0.059).

Conclusion: SE grade is useful to classify NACLMs in different groups distinguished by their clinical, pathological, and molecular features. These results endorse the new WHO classification of low- and high-CSD melanomas. Moreover, they highlight the importance of reporting the grade of SE in the pathological report.