MARGIN CONTROL FOR LENTIGO-MALIGNA

Background: Lentigo maligna is an in situ malignant melanoma for which the treatment of choice is surgical excision. The current recommendat ion is local resection with a 0.5 to 1.0 cm margin of normal skin. Bec ause many lesions occur on the face, the narrowest possible margin red uces the amount of scarring. Controversy surrounds the use of Mohs mic rographic surgery to preserve normal skin and resect the lentigo malig na. Objective: The purposes of this prospective study were to determin e the narrowest possible margin of resection of lentigo maligna and th e accuracy of frozen and fixed histologic specimens from those margins . In addition, the benefit of adjunctive immunoperoxidase staining wit h antibodies to S-100 protein and HMB-45 monoclonal antibody was exami ned retrospectively. Methods: A Wood's light was used to delineate the clinical margin in 16 cases of lentigo maligna that were resected wit h serial excisions 0.3, 0.6, 1.0, and 1.3 cm from the clinical border of the tumor. Frozen sections were confirmed by fixed histopathologic specimens. Subsequently these tissue blocks were examined with antibod ies to S-100 protein and HMB-45 monoclonal antibodies. Patients were o bserved 5 to 9 years. Results: One of the 16 patients had a recurrence 8 years after surgery. Although lesions with a diameter less than 2.0 cm had narrower margins of resection, the majority of lesions were re sected with a margin of 0.6 to 1.0 cm. Lesions larger than 3.0 cm in d iameter required a margin of resection greater than 1.0 cm. The antibo dy to S-100 protein was neither sensitive nor specific enough to assis t with identification of the process. HMB-45 monoclonal antibody was s ensitive and assisted in the identification of atypical melanocytes.