Study Background and Disease Burden
Melanoma in situ (MIS) is an early-stage, non-invasive form of melanoma, characterized by malignant melanocytes confined within the epidermis without dermal invasion. The diagnosis of MIS, particularly non-lentigo maligna (non-LM) and non-acral lentiginous melanoma (non-ALM) subtypes, has increased alongside heightened skin cancer screening efforts, raising concerns about overdiagnosis and overtreatment. While lentigo maligna and acral lentiginous MIS subtypes have been extensively studied, there remains limited robust evidence regarding the natural history, local recurrence rates, and optimal management strategies for non-LM/non-ALM MIS. Traditionally, treatment involves excisional biopsy for diagnosis followed by wide local excision to clear any residual disease and prevent progression to invasive melanoma and metastasis. However, the necessity and extent of wide excision in cases with clear margins after initial biopsy remain unclear. This study addresses a critical unmet need to delineate recurrence risks and the impact of margin status and excision width on long-term outcomes in these MIS subtypes.
