Association Between Anatomical Subsite and Invasive Disease in Head and Neck Lentigo Maligna and Lentigo Maligna Melanoma.

Lentigo maligna (LM) and LM melanoma (LMM) predominantly arise on chronically sun-damaged head and neck skin and are often considered biologically uniform across facial locations. Whether invasive potential varies by anatomical subsite remains unclear. We aimed to evaluate the association between predefined head and neck subsites and invasive phenotype in LM and LMM. In this retrospective cohort study, 134 patients with histopathologically confirmed LM and LMM were analyzed. Head and neck lesions were stratified a priori into scalp, nose, ear, periocular region, other facial areas, and neck. Multivariable linear and logistic regression models assessed associations between anatomical subsite, Breslow thickness, and invasive disease, adjusting for age and sex. Among 118 head and neck lesions, 50% were invasive. Anatomical subsite was independently associated with invasive disease (p = 0.0025), with auricular lesions demonstrating the highest frequency of invasion and nasal and periocular lesions showing significantly lower odds. Among invasive LMM, nasal lesions also demonstrated significantly lower Breslow thickness compared with auricular lesions in adjusted analysis (p = 0.026). To conclude, head and neck LM and LMM demonstrated significant anatomical differences in invasive presentation. These findings suggest that anatomical subsite may influence the likelihood of invasive disease and support greater anatomical consideration during clinical evaluation.