18227 Side effect: Characterizing laterality and site-specific patterns in lentigo maligna and lentigo maigna melanoma on the human body

Abstract

Melanoma is known to have a left-sided laterality, yet few studies have examined the anatomic variations in the subtypes lentigo maligna (LM) and lentigo maligna melanoma (LMM). Here we aimed to examine laterality and anatomic distribution of LM and LMM at a single university center. A total of 392 biopsy cases (241 LM and 151 LMM) from 2008 to 2018 were included in this study. Chi-square tests were used to evaluate LM/LMM based on gender, body site, laterality, and metastasis. Analysis of variance models were used to compare Breslow depth. There was no overall statistically significant laterality (left 54.5% vs right 45.5%, P = .0890), however, there was a significant increase in left-sided LM/LMM on the head/neck (left 59.1% vs right 40.9%, P = .0178). LM/LMM showed the following frequencies per body site: head/neck 49.7%, upper limbs 25.3%, trunk 16.8%, and lower limbs 8.3%. Men demonstrated a higher incidence of LM/LMM on the head/neck and trunk (head/neck men 58.2% vs women 35.0%, trunk 18.9% men vs 13.3% women, P < .0001), while women showed a higher incidence on extremities (upper limbs men 20.5% vs women 33.6%, lower limbs men 2.4% vs women 18.2%, P < .0001). There was a significant increase in metastasis on the upper limbs (LMM:LM ratio 1.11 upper limbs; P = .0018) and on the right side of the female body (LMM:LM ratio 1.36 right; P = .0257). Overall, LM/LMM does not share left-sided laterality patterns with melanoma, except when on the head/neck. Like melanoma, LM/LMM is commonly found on the head/neck and upper extremities. These findings may aid in diagnosis of LM/LMM.