Johnson square procedure for lentigo maligna and lentigo maligna melanoma

Abstract

Background: Lentigo maligna (LM) and lentigo maligna melanoma (LMM) can be difficult to manage surgically. Predetermined margins can be inadequate because of subclinical spread, or can affect function when margins are adjacent to the eye or mouth.

Aim: To describe our 5-year experience in Nottingham of using the staged square procedure (Johnson square) in excising difficult facial LM and LMM.

Methods: The square procedure is a staged technique useful for ill-defined lesions and for lesions that have a high recurrence rate due to subclinical spread. It uses paraffin wax-embedded peripheral vertical sections for margin control, ensuring complete clearance as the surgical margins are usually examined at distances of 2-5 mm from the periphery of the lesion.

Results: We treated 21 patients with LM or LMM with the staged square procedure over a 5-year period. Of the 21 patients, 10 needed only one stage of surgery, 6 needed two stages, 3 needed three stages and 2 needed four stages. To date, there has been only one recurrence, which was of an extensive lesion that crossed the medial canthus, making margin control impossible because of the anatomical limitations.

Conclusions: The staged square procedure is an effective treatment for LM and LMM. It attempts to conserve tissue while ensuring a higher clearance rate. This offers favourable cosmetic outcomes and better prognosis, especially for facial LM and LMM.