Conventional surgery compared with slow Mohs micrographic surgery in the treatment of lentigo maligna: a retrospective study of 62 cases.

INTRODUCTION Surgical excision with margins of 0.5cm is the standard treatment for lentigo maligna (LM). Excision, however, is often incomplete as many of these tumors have indistinct borders. OBJECTIVE To identify clinical predictors of subclinical extension in primary and recurrent LM of the head and thereby determine which lesions might require wider surgical margins. MATERIAL AND METHODS We reviewed the clinical records of patients with LM of the head treated definitively with conventional surgical excision or slow micrographic Mohs surgery (MMS) at the dermatology department of Instituto Valenciano de Oncología between January 1993 and April 2011. RESULTS Surgical margins larger than 0.5cm were required in 69.2% of recurrent LM and 26.5% of primary LM. Factors associated with the need for wider margins were prior treatment that might have interfered with the clinical delineation of the border, lesions in the center of the face, and skin phototypes III to V. CONCLUSIONS Surgical margins of 0.5cm are inadequate for the treatment of a considerable number of LM lesions located on the head, particularly if these are recurrent. Slow MMS using paraffin-embedded sections appears to be the treatment of choice in such cases, particularly for recurrent lesions or lesions with poorly defined borders or possible subclinical extension.